Source: UNIV OF HAWAII submitted to
POSTHARVEST PHYSIOLOGY OF FRESH HAWAIIAN COMMODITIES
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
REVISED
Funding Source
Reporting Frequency
Annual
Accession No.
0001161
Grant No.
(N/A)
Project No.
HAW00862-H
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Oct 1, 2009
Project End Date
Sep 30, 2014
Grant Year
(N/A)
Project Director
Paull, R. E.
Recipient Organization
UNIV OF HAWAII
3190 MAILE WAY
HONOLULU,HI 96822
Performing Department
Tropical Plant & Soil Science
Non Technical Summary
The marketing of high quality fresh Hawaii fruits, vegetables, and ornamentals requires that the commodity be grown for optimum quality, and harvested and handled post-harvest to maintain that quality. Postharvest physiology and handling research plays a critical role in assuring the maintenance of commodity quality. Postharvest quality is in large measure set before harvest, hence preharvest conditions need to be considered in evaluation of quality and its maintenance. The smaller quantities of tropical commodities produced, the distances to market, the commodities inability to be stored at low temperatures and the presence of fruit flies and other insects requiring postharvest treatments compound the research needed to ensure quality products are marketed. In this project, we will continue collaboration with industry groups to directly address their needs for postharvest applied research and carry out long-term basic studies using molecular techniques to develop new strategies to address postharvest problems for Hawaii's horticultural crops. Research will continue on pineapple looking for solutions to the precocious flowering and cultural practices to modify acidity levels. Papaya research will focus on looking for non-pesticide disease control and the modification of fruit ripening to increase storage life. Irradiation and ethylene interact during papaya fruit ripening and this interaction will be another research effort to reduce its impact. Research on other tropical fruits and vegetables has been short term in nature to address immediate concern especially in providing up to date information in handling these commodities. Ornamental research will continue to look for approaches to maintain product quality and thereby extend vase life and reduce postharvest losses. The potential for Jatropha as a biofuels will remain synchronization of field flowering and selection of material will non-toxic seed cake.
Animal Health Component
25%
Research Effort Categories
Basic
50%
Applied
25%
Developmental
25%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2011099102015%
2041099102020%
5031099102050%
7121099102015%
Goals / Objectives
Pineapple 1. Using biotechnology and management strategies to minimize precocious flowering. 2. Determine the factors that control the sugar/acid ratio in the new low acid varieties. 3. Determine the importance of different preharvest factors that influence postharvest fruit quality. 4. Assist industry to find solutions to new problems as they arise. Papaya 1. Develop, via backcrossing and selection, varieties that possess slow ripening traits and have commercial potential. 2. Determine the role and regulation of cell wall degrading enzymes in ripening related fruit softening. 3. Determine the relationship between the physiological effects of the insect disinfestation irradiation treatment on fruit ripening and ethylene. 4. Assist industry to find solutions to new postharvest problems as they arise. Tropical Fruit 1. Develop, in conjunction with industry, suitable postharvest handling protocols for fruit export. 2. Prepare and distribute extension publication on the postharvest handling and physiology of tropical fruit. 3. Assist industry to find solutions to new problems as they arise. Vegetables 1. Develop an assay for taro acridity. 2. Assist agents and industry in finding solutions to postharvest handling problems. 3. Determine the influence of preharvest environment and production methods on postharvest quality. Ornamentals 1. Assist industry in developing new handling practices to assure Hawaii exports a high quality product. 2. Determine the factors that reduce quality and evaluate practices that maintain product quality. Biofuels 1. Collaborate with the biofuels group to develop production practices that increase mechanical harvesting efficiency for Jatropha by synchronization of flowering. 2. Development Jatropha varietal selections with low toxin levels in the seed cake.
Project Methods
A. Pineapple Objective 1 -Flowering: Weekly treatments of ReTain (AVG) at 100 ppm will be applied as 125 or 250 gallons per acre in early December to reduce the percentage of flower development (budding and thus sharpened the harvest peak. We have generated 18 independent transgenic pineapple plant lines with an ACS antisense construct. Plants of the individual transformed lines and the control will be grown in a randomized plot design in pots at the University of Hawaii Whitmore Sub-Station. Plants will be monitored fortnightly for six months from early December through May. At first indication of flowering (red bud stage), the plant will be scored as having flowered. If flowering has not occurred by May, the plants that have not flowered will be induced to flower with Ethephon. The Ethephon solution (100 ppm) will be poured into the heart of the plant with about 25 mL per plant. Pineapple Objective 2. - Low Acid Fruit - Fruit are to be randomly selected from field trials having different management strategies fertilization and irrigation, and returned to the laboratory within 4 hours of harvest. Twenty five fruit are to be evaluated with in 24 hours of harvest and the remaining twenty fruit stored for 14 days at 7oC, then 7 days at 22oC, before evaluation. Papaya Objective 1 The ripening variant, Line #8 softens to the edible stage in 6 days versus 11 days for the commercial varieties. At the other extreme, Line #4-16 does not begin to soften until 14 days from mature green stage and reaches the edible soft stage at 21 days. We have found a single QTL for this slow ripening trait and are now using papaya microarrays that we developed to determine the expression of the possible transcription factors present in this QTL region. The microarray analysis will be confirmed with RT-qPCR. Papaya Objective 2 - Determine the regulation of cell wall degrading enzymes in ripening related fruit softening. The objective of this section of our project is to complete the evaluation of the molecular biology and physiology of 8 PCR-positive putative antisense endoxylanase lines and 32 other possible antisense lines that may have delayed softening. The full-length endoxylanase clone (CpaEXY1) was inserted behind the CaMV-35S or ubitiquin promoters and in front of a NOS 3' terminator sequence so that the xylanase was in the antisense direction. DNA insertion (determined by Southern analysis), RNA expression, endoxylanase activity, and protein content (determined by using endoxylanase antibodies) will be assayed to characterize the putative transformed lines. Fruit ripening will be evaluated by measuring respiration rate, ethylene production, and firmness.

Progress 10/01/12 to 09/30/13

Outputs
Target Audience: Peer researchers working in the same area, undergraduate and graduate students, extension agents and farmers. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? We have been able to collaborate with a number of groups both nationally and internationally to develop new expertise inthe laboratory. This new knowledge has been passed onto to graduate students through in-laboratory training and in formal courses How have the results been disseminated to communities of interest? The results have been released via peer reviewed publications, and via extension bulletins and farmer workshops. What do you plan to do during the next reporting period to accomplish the goals? We will continue our projects dealing with papaya fruit bitterness and fruit ripening gene expression. With pineapple we will start field trials to modify fruit acidity and translucency, gene expression during fruit development and CAM metabolism. For taro, we will continue characterizing acidity proteins , express them and confirm acridity, then develop a rapid assay for acridity. A new project on low chill peaches will be initiated with our rolebeing to evaluate fruit quality and in collaboration with extension agent help in analysing the growth and flowering data.

Impacts
What was accomplished under these goals? Reports are occasionally heard of a bitterness in papaya fruit in the market. Most frequently these reports are reported for fruit from newly fruit trees and when harvested during the cooler months of the year. We have attempted to induce bitterness in harvested color break fruit. Papaya fruit did not develop bitterness when stored at 10oC for 2 weeks, however, after one week at 2oC bitterness was detected in more than 70% of the fruit. Bitterness began to occur after four days at 2oC. The bitterness was limited to the stem end of the fruit in our experiments. The nature of the bitter principal in papaya is unknown. Preliminary data suggests that holding fruit at a constant 2oC had less bitterness development than if the temperature fluctuated between 2oC and 12oC. Soil condition, field temperature and age of the fruit may all have a role in the development of bitterness in papaya. Papaya fruit at different stages of ripeness were evaluated for changes in firmness and colour of the flesh and skin. RNA was extracted from all the fruit at six stages of ripeness from mature green to full ripe colour. The RNA was Illumina Sequenced after library construction by our collaborator at the University of Illinois. The normalization and statistical evaluation of differential gene expression has been performed using edgeR with a p-value cut-off of 0.05 and using the Benjamini-Hochberg (1995) method for multiple testing correction. The raw data was normalized according to the default procedure of the differential expression analysis package used. The dispersion was estimated using the auto setting. We are now analyzing the unique reads that can be aligned to the predicted genes for papaya looking for changes that are related to fruit ripening. We constructed a cytogenetic map of the papaya sex chromosome (chromosome 1) by hybridizing 16 microsatellite markers and 2 cytological feature-associated markers on pachytene chromosomes using fluorescence in situ hybridization (FISH). This work was done in collaboration with the University of Illinois. Sequence analysis of 18 scaffolds in total length of 15 Mb revealed higher gene density towards the telomeres and lower gene density towards the centromere, and a relatively higher gene density in the long arm than in the short arm. In collaboration with colleagues in Mexico we have shown a pre-endoxylanase at 63.9 kDa in the color-break fruit and an active endoxylanase at 32.5 kDa that was only found in ripe fruit, when the highest enzymatic activity was obtained. Immunodetection on two-dimensional gel electrophoresis (2DE) protein blots showed three isoforms of the pre-endoxylanase at color-break and ripe stages and, four isoforms in ripe fruit that were absent in color-break fruit. In collaboration with a New Zealand group we also showed that this endo-xylanase besides having hydrolases activity also had endotransglycosylase activity that could be involved in remodelling or re-arrangement of heteroxylans of the cellulose-non-cellulosic cell wall framework. Early in the year we sampled fruit of 73-114 at eight stages of development from the end of flowering to full yellow and ripe fruit. Development was characterized by fruit weight, flesh colour, titratable acidity and soluble solids. RNA was extracted, libraries made and sequenced. Due to the lack of a fully sequenced genome for pineapple alignment has proven difficult. We are now collaborating on improving the genome sequencing data. Of particular interest in our analysis are gene expression profiles associated with acidity and translucency. We are also collaborating in sampling pineapple leaves for CAM genes expression study. Raphide in taro are not responsible for the acridity. Raphides are found in Fuchsia leaves and duckweed though neither plant causes acridity. Taro raphide was extracted from taro leaf petiole and corm followed the procedure developed in our laboratory. Proteins were then separated from raphide using TRI reagent and dissolved in IEF rehydration buffer and separated by 2D electrophoresis. Protein spots on 2-D gel were cut off and sent to the Taplin Biological Mass Spectrometry Facility, at Harvard Medical School for sequencing. There are more than 30 spots on the 2-D gel on leaf samples. Ten of the larger spots have already been sequenced. Most of the sequenced proteins are less than 43 Kid in molecular weight. We are now extracting addition raphides and plan on sequencing the remainder of the spots. The sequenced were searched against the rice genome database, in the absence of a taro genome sequence, and predicted genes were identified. Four of the ten proteins sequenced to date occurred more than once in the sample sequenced. Two of those predicted genes contain sequences of known allergens. One sequence has high homology to profiling and was identified on two protein spots. Profilin is a known human allergen. In addition, Cla h5, an allergen that occurs in hazelnut was also identified. The Veratox test system for hazelnut allergen was used to determine its feasibility to screen for some of the predicted allergen in taro. Homogenates of taro leaf and corm from more acrid taro lines tested positive. Among all the taro cultivars tested, JC#6 was the most acrid, the acridity occurring in both the leaf and corm. Binglong, a commercial table taro, only showed acridity in leaf. Two dimension gels run with protein from corms of JC#6 and Binglong when compared to identify the possible acridity causing protein. A spot with molecular weight of 28 Kid was present in JC#6 but absent in Bing long, the protein was sent out for sequenced. We have collaborated with national and internal partners in the analysis of predicted genes from Sacred Lotus and Asian Pear. The lotus genome (Nelumbo nucifera (Gaertn.)) lacks the paleo-triplication found in other eudicots and has evolved remarkably slowly with fewer nucleotide mutations. The slow nucleotide substitution rate in sacred lotus makes it a better resource than the current standard, grape, for reconstructing the pan-eudicot genome, and should accelerate the comparative analysis between eudicots and monocots. In many cell wall transferases and hydrolases families, lotus had fewer members in most families when compared to Arabidopsis. Lotus had similar or fewer members in each family as found in poplar, grape and papaya. The exceptions were in the sialyl and beta-glucuronsyl transferases where similar number were found as in the core eudicots. Lotus had similar numbers of polygalacturonase and pectin methyl esterases as found in Arabidopsis but fewer in all other hydrolases families. For starch degradation, lotus had only two alpha amylases predicted genes versus eight to ten in other eudicots, with similar numbers of beta amylase genes predicted. Lotus also had less than half the number of genes predicted for the enzymes involved in lignin and tannin synthesis compared to Arabidopsis. The stress plant growth regulator ethylene’s synthesis, reception and response predicted genes were fewer in lotus than other eudicots. Only two ethylene receptor genes were predicted in lotus with five reported for Arabidopsis and six for tomato. The draft genome of the Asian pear (Pyrus bretschneideri) using a combination of BAC-by-BAC and next-generation sequencing was completed. Our role was in the identification of genes predicted for cell wall metabolism and carbohydrate metabolism and their annotation.

Publications

  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Paull, R.E., Carroll, A., and Chen, N.J. 2013. Lotus Cell Walls and the Genes Involved in its Synthesis and Modification. Tropical Plant Biology 6: 152160.
  • Type: Book Chapters Status: Published Year Published: 2013 Citation: Paull, R.E., Wu, P.F., and Chen, N.J. 2013. Genomics of Papaya Fruit Development and Ripening. p241-275. In. Genetics and Genomics of Papaya. Ray Ming and Paul Moore (Editors). Springer, New York
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Ming, R., VanBuren, R., Liu, Y., Yang, M., Han, Y., Li, L-T., Zhang, Q., Kim, M-J., Schatz, M.C., Campbell, M., Li, J., Bowers, J.E., Tang, H., Lyons, E., Ferguson, A.A., Narzisi, G., Nelson, D.R., Blaby-Haas, C.E., Gschwend, A.R., Jiao, Y., Der, J.P., Zeng, R., Han, J., Min, X., Hudson, K.A., Singh, R., Grennan, A.K., Karpowicz, S.J., Watling, J.R., Ito, K., Robinson, S.A., Hudson, M.E., Yu, Q., Mockler, T.C., Carroll, A., Zheng, Y., Sunkar, R., Jia, R., Chen, N., Arro, J., Wai, C.M., Spence, A., Han, Y., Xu, L., Zhang, J., Peery, R., Haus, M.J., Xiong, W., Walsh, J.A., Wu, J., Wang, M-L., Zhu, Y.J., Paull, R.E., Britt, A.B., Du, C., Downie, S.R., Schuler, M.A., Michael, T.P., Long, S.P., Ort, D.R., Somerville, C.R., Schopf, J.W., Gang, D.R., Jiang, N., Yandell, M., dePamphilis, C.W., Merchant, S.S., Paterson, A.H., Buchanan, B.B., Li, S., and Shen-Miller, J.. 2013 Genome of the long-living sacred lotus (Nelumbo nucifera Gaertn.).Genome Biology 14: R41
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Johnston, S.L., Prakash, R., Chen, N.J., Kumagai, M.H., Turano, H.M., Cooney, J.M., Atkinson, R.G., Paull, R.E., Cheetamun, R., Bacic, A., Brummell, D.A., and Schr�der, R. 2013. An enzyme activity capable of transglycosylation of heteroxylan polysaccharides is present in plant primary cell walls. Planta 237: 173 - 187
  • Type: Journal Articles Status: Published Year Published: 2012 Citation: Pant, A.P., Radovich, T.J.K, Hue, N.V., and Paull, R.E. 2012. Biochemical properties of compost tea associated with compost quality and effects on pak choi growth. Scientia Horticulturae 148: 138-146.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Wu, J., Wang, Z., Shi, Z., Zhang, S., Ming, R., Zhu, S., Khan, M.A., Tao, S., Korban, S.S., Wang, H., Chen, N.J., Nishio, T., Xu, X., Cong, L., Qi, K., Huang, X., Wang, Y., Zhao, X., Wu, J., Deng, C., Gou, C., Zhou, W., Yin, H., Qin, G., Sha, Y., Tao, Y., Chen, H., Yang, Y., Song, Y., Zhan, D., Wang, J., Li, L., Dai, M., Gu, C., Wang, Y., Shi, D., Wang, X., Zhang, H., Zeng, L., Zheng, D., Wang, C., Chen, M., Wang, G., Xie, L., Sovero, V., Sha, S., Huang, W., Zhang, S., Zhang, M., Sun, J., Xu, L., Li, Y., Liu, X., Li, Q., Shen, J., Wang, J., Paull, R.E., Bennetzen, J.L., Wang, J., and Zhang, S. (2012). The genome of pear (Pyrus bretschneideri Rehd.). Genome Research.23: 396-408
  • Type: Journal Articles Status: Published Year Published: 2012 Citation: Theodore J.K. Radovich, Archana Pant, Ian Gurr, Ngyuen V. Hue, Jari Sugano, Brent Sipes, Norman Arancon, Clyde Tamaru, Bradley K. Fox, Kent D. Kobayashi, and Robert Paull. 2012. Innovative Use of Locally Produced Inputs to Improve Plant Growth, Crop Quality, and Grower Profitability in Hawaii. HortTechnology 22: 738-742.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Iniestra-Gonzaleza, J.J., Lino-Lopezb, G.J., Paull, R.E., de la Rosad, A.P.B., Mancilla-Margallie, N.A., Sa.nudo-Barajasf, J.A., Ibarra-Junqueraa, V., Chen, N.J., Hernandez-Velascob, M.A., and Osuna-Castro, J.A. 2013. Papaya endoxylanase biochemical characterization and isoforms expressed during fruit ripening. Postharvest Biology and Technology 81: 1322


Progress 10/01/11 to 09/30/12

Outputs
OUTPUTS: Papaya xylan endotransglycosylase has been identified and purified that can transglycosylate heteroxylan polysaccharides in the presence of xylan-derived oligosaccharides. This activity was also found in a range of other fruits, imbibed seeds and rapidly growing seedlings of cereals. Xylan endotransglycosylase from ripe papaya fruit uses a range of heteroxylans as donor molecules. As acceptor molecules, the enzyme preferentially used xylopentaitol over xylohexaitol or shorter-length acceptors. Xylan endotransglycosylase is active over a broad pH range and could perform transglycosylation reactions up to 55 C. We identified fourteen QTL with phenotypic effects for papaya fruit size and shape across six linkage groups (LGs) with clusters of two or more QTL on LGs 02, 03, 07 and 09. These loci contain homologs to the tomato fruit QTL ovate, sun and fw2.2 that regulate fruit size and shape. We sequenced the two pineapple parental genomes, F153 (A. comosus, 2n=2x=50) and HANA64 (A. bracteatus, 2n=2x=50), to develop microsatellite markers and to obtain the genomic sequence for pineapple genome structure study and comparative genomic analysis. Novel pineapple specific repeat were identified and a customized library of repeat elements compiled. Comprehensive repeat analysis identified 34.8% and 26.63% of assembled genome covered by repeats for F153 and HANA 64, respectively. Retrotransposon) elements were the major elements with LTR elements being the most abundant. RAD-Seq was used to construct a high-density genetic map of pineapple. Two genetic maps were constructed, one for each of the parental genomes. A linkage map of F153 was constructed using 973 RAD-Seq markers. This map consisted of 29 linkage groups and spanned a total length of approximately 1630 cM, with an average interval of 1.68 cM. Another linkage map, composed of 2048 RAD-Seq markers in 28 linkage groups and covered a total length of 1373.9 cM, was constructed for HANA 64 genome. To map the trait of leaf margin spine, we created a F2 mapping population with 492 individuals. The F2 mapping population was used to map the loci of major genes controlling the leaf margin spine. Postharvest leaf blackening of Protea flowers is a function primarily of the stage of flower opening at harvest and clonal source of the tree. The focus has been on enhancing the role of glucose pulse treatments after harvest and before shipping. Glucose has been recommended and we have confirmed that it does significantly delay leaf blackening and that the ethylene inhibitor (1-MCP) by itself has no effect. Pulsing with 2.5% glucose for five hours before shipping has only a slight effect in delaying postharvest leaf blackening though including 1-MCP with the glucose pulse improved the response in delaying blackening. Pulsing with 2.5% glucose for five hours before packing and hold in the carton for 2 or 5 days did not reduce the rate of leaf blackening. The results together imply that a continuous supply of glucose is necessary PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Papaya fruit postharvest losses of up to 75% have been reported to Hawaii shippers by mainland USA wholesalers and retailers. These losses are associated with fruit ripening and postharvest disease, often associated with storing color-break fruit for more than three weeks at temperatures of 10C or lower temperatures and mechanical injury. Control of ripening and associated with softening can contribute to the reduction in these losses. The xylan endotransglycosylase activity, like xyloglucan and mannan endotransglycosylase activities could be involved in remodelling or re-arrangement of heteroxylans of the cellulose-non-cellulosic cell wall framework and hence softening during fruit ripening. This supports earlier finding that when this activity is suppressed the fruit flesh develops a rubbery texture. We now have another potential control point to regulate fruit softening during ripening. Pineapple is the No. 1 fruit crop in Hawaii and the third most important commercial tropical fruit crop in world production after banana and citrus. Besides the commercial value of its fruits, its leaves are the most promising source for nano-cellulose materials that may be used as a plastic alternative in the future. As a crassulacean acid metabolism (CAM) plant species, pineapple is the best representative of this under-explored node of angiosperms. However, very little molecular genetics and genomics research has been carried out on this crop. The sequence data we have generated is the largest data set for pineapple. And the genetic maps we have constructed are the most saturated genetic maps of pineapple so far. The genome sequence generated by this proposed project will significantly advance our understanding of the genome organization of pineapple, will simplify the process of isolation of homologous genes of interest, and will develop a better understanding of plant evolution. The high density genetic map constructed by the proposed project will have profound impact on pineapple improvement through better understanding of relevant biology and direct application of genetic and genomic tools in breeding programs. Results of the proposed research will significantly advance the development of genomic tools and knowledge for pineapple improvement. Protea flowers for shipment should be harvested when full-grown and with the bracts still closed at the top of the flower. Flowers can be held in a glucose solution overnight before packing. Plants to be propagated for new planting need to be evaluated for leaf blackening and vase life after a simulated shipping treatment.

Publications

  • Sugano, J., Diaz-Lyke, M.D.C., Hamasaki,R., Fukuda, S., Paull, R.E., and Nakamoto, S.T. 2011. Papaya Maturity Chart: Proper Fruit selection During Harvest Improves Market Value. Poster Funded by USDA Risk Management Agency grant RMA J630365 (English and Ilacano).
  • Apita, B., Paull, R.E., and Ketsa, S. 2012. Increased activities of phenyalanine ammonia lyase, peroxidase, and cinnamyl alcohol dehydrogenase in relation to pericarp hardening after physical impact in mangosteen (Garcinia mangostana L.). Journal of Horticultural Science & Biotechnology 87:231-236.
  • Blas, A. L., Yu, Q., Veatch, O.J., Paull,R.E., Moore, P.H., Ming, R. 2012. Genetic mapping of quantitative trait loci controlling fruit size and shape in papaya. Molecular Biology 29:457-466
  • Ming, R., Yu, Q., Moore, P.H., Paull, R.E., Chen, N.J., Wang,M., Zhu, Y.J., Schuler, M.A., Jiang, J., Paterson, A.H. 2012. Genome of papaya, a fast growing tropical fruit tree. Tree Genetics and Genomics 8:445-462.


Progress 10/01/10 to 09/30/11

Outputs
OUTPUTS: Three yeast isolates that were earlier shown to have potential biological activity were further tested in vivo on papaya fruit obtained from commercial grower. Half the treated and inoculated fruit were stored at 10oC for 10 days before ripening at ambient temperature. In addition to the yeast isolates, 0.5% thyme oil, 1.5% medium molecular weight chitosan and Sri Lankan wax were also tested for their postharvest disease control activities. When the biological agents were applied on the same day as the pathogen inoculation, the antagonistic activity was not noticeable in papaya ripened at ambient temperature without cold storage. Neither thyme oil nor yeast isolates reduced the infection of Collectotrichum. The yeast isolates #581, and #1061 effectively reduced the Anthracnose development in papaya after cold storage. Initial studies indicated that the application time of the control agent influenced the effectiveness its antagonist activity. The biocontrol agent was more effective if applied later, if cold storage was not involved. All three yeast isolates tested, #581, #961 and #1061 showed antagonistic activity against Collectotrichum when applied one day after pathogen inoculation in papaya ripened at ambient temperature. However, when the papaya were stored at 10oc before ripening, only yeast isolate #1061 was effective in reducing the Collectotrichum infection. We constructed a molecular cytogenetic map of the papaya sex chromosome and investigated variations in recombination rate and genomic composition along the chromosome. Sixteen microsatellite markers from the sequence-tagged genetic map and two morphological feature associated markers were used to construct a molecular cytogenetic map of papaya chromosome 1. The centromeric heterochromatic region contains more repetitive sequences and less number of genes compared with the two arms. Two pineapple parent genomes, F153(A. comosus) and HANA64 (A. bracteatus) were sequenced using Roche 454 to develop microsatellite markers and to obtain the genomic sequence data for pineapple genome structure study and comparative genomic analysis. The average read length was 453 for F153 and 497 for HANA64 with 800.2Mbp and 721.7 Mbp read, respectively. From the assembled contigs, we designed 8,542 pairs of SSR primers. After excluding redundant primers and duplicated primers we designed from EST sequences, we obtained 7,967 pairs of unique primers, which are about 3,000 more primers than we proposed. We are annotating the genomic sequences looking for sequences relevant for fruit quality. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Papaya fruit postharvest losses of up to 75% have been reported to Hawaii shippers by mainland USA wholesalers and retailers. These losses are associated with postharvest disease, often associated with storing color-break fruit for more than three weeks at temperatures of 10̊C or lower temperatures and mechanical injury. Postharvest disease has been controlled by hot water dips, hot water spray treatments and fungicides. In this project, we are developing and evaluating a biological-based approach to postharvest disease control. Microorganisms commonly isolated from papaya fruit are being evaluated for their ability to control postharvest disease by their actions as antagonistic microorganisms to the disease carrying microorganisms. The output from this project would provide a postharvest disease control for organic papaya production and an alternative to fungicide in conventional production. We reported the 1st molecular cytogenetic map of the papaya chromosome 1. This map corrected the errors on the genetic map and has been integrated with genetic and physical maps, which provides essential information for finishing sequence of papaya sex chromosome and relevant postharvest related genes. An accurate chromosome map is an essential resource for genome sequence assembly, genetic and physical mapping of targeted genes, and papaya improvement via genetic engineering and gene manipulation. The integrated genetic, physical, and chromosome map will be a useful tool for the papaya research community and ultimately benefit the papaya growers with improved papaya cultivars and products. Pineapple is the No. 1 fruit crop in Hawaii and the third most important commercial tropical fruit crop in world production after banana and citrus. As a crassulacean acid metabolism (CAM) plant species, pineapple is the best representative of this under-explored node of angiosperms. However, very little molecular genetics and genomics research has been carried out on this crop. The sequence data we have generated is the largest data set for pineapple. The genome sequence generated by this proposed project will significantly advance our understanding of the genome organization of pineapple, will simplify the process of isolation of homologous genes of interest, and will develop a better understanding of plant evolution. Results of the proposed research will significantly advance the development of genomic tools and knowledge for pineapple improvement.

Publications

  • Paull, R. E. and Chen, N. J. 2011. Postharvest Management of Tropical Flowers. In: Luna-Esquivel, G., Rodriguez-Rodriguez, B. B., Juarez-Lopez, P., Santillan-Ortega, C., Flores-Canales, R., Isiordia-Aquino, N., Cambero-Campos, O. J., Robles-Bermudez, A. (compiladores). Memoria de resumenes del XIII Congreso Nacional y VI Internacional de Horticultura Ornamental. 23 al 28 de Octubre del 2011. Nuevo Vallarta, Nayarit, Mexico
  • Sugano, J., Diaz-Lyke, M. D. C., Hamasaki, R., Fukuda, S., Paull, R., and Nakamoto, S. T. 2011. How to Minimize On-Farm Papaya Fruit Damage. Poster Funded by USDA Risk Management Agency grant # RMA J630365
  • Love, K. and Paull, R.E. 2011. Soursop. University of Hawaii at Manoa, College of Tropical Agriculture and Human Resources. Fruit and Nuts Publication F_N-22.
  • Love, K. and Paull, R.E. 2011. Jackfruit. University of Hawaii at Manoa, College of Tropical Agriculture and Human Resources. Fruit and Nuts Publication F_N-19.
  • Love, K. and Paull, R.E. 2011. Jaboticaba. University of Hawaii at Manoa, College of Tropical Agriculture and Human Resources. Fruit and Nuts Publication F_N-20.
  • Love, K. and Paull, R.E. 2011. Rollina. University of Hawaii at Manoa, College of Tropical Agriculture and Human Resources. Fruit and Nuts Publication F_N-21.
  • Love, K. and Paull, R.E. 2011. Bilimbi. University of Hawaii at Manoa, College of Tropical Agriculture and Human Resources. Fruit and Nuts Publication F_N-23.
  • Love, K. and Paull, R.E. 2011. Abiu. University of Hawaii at Manoa, College of Tropical Agriculture and Human Resources. Fruit and Nuts Publication F_N-24.
  • Vasu, P. J., Savary, B. J., Kim, Y., Cameron, R. G., Paull, R. E. 2011. Isolation and identification of Carica papaya fruit pectin methylesterases. Plant Biology 2011. Minneapolis Convention Center, August 6th to 10th. (Abstract & poster)


Progress 10/01/09 to 09/30/10

Outputs
OUTPUTS: Carotenoid pigments in fruits are indicative of the ripening process and potential nutritional value. Papaya fruit flesh color is caused by the accumulation of lycopene or b-carotenoids in chromoplasts. To uncover the molecular basis of papaya flesh color, we took map-based cloning and candidate gene approaches using integrated genetic and physical maps. A DNA marker tightly linked to flesh color colocalized on a contig of the physical map with a cDNA probe of the tomato (Solanum lycopersicum) chromoplast-specific lycopene b-cyclase, CYC-b. Candidate gene sequences were obtained from amplified fragments and verified by sequencing two bacterial artificial chromosomes containing the two alleles. Sequence comparison revealed a 2-bp insertion in the coding region of the recessive red flesh allele resulting in a frame-shift mutation and a premature stop codon. A color complementation test in bacteria confirmed that the papaya CpCYC-b is the gene controlling fruit flesh color. Sequence analysis of wild and cultivated papaya accessions showed the presence of this frame-shift mutation in all red flesh accessions examined. Conserved microsynteny of the CpCYC-b region is indicated by colinearity of two to four genes between papaya, Arabidopsis (Arabidopsis thaliana), grape (Vitis vinifera), and tomato. Our results enhanced our understanding of papaya flesh color inheritance and generated new tools for papaya improvement. Papaya cultivars show a wide variation in fruit softening rates, a character that determines fruit quality and shelf life, and thought to be the result of cell wall degradation. The activity of pectin methylesterase, β-galactosidase, endoglucanase, endoxylanase and xylosidase were correlated with normal softening, though no relationship was found between polygalacturonase activity and softening. When softening was modified by 1-MCP treatment, a delay occurred before the normal increase in activities of all cell wall activities except endoxylanase which was completely suppressed. Significant cell wall mass loss occurred in the mesocarp tissue during normal softening, but did not occur to the same extent following 1-MCP treatment. During normal softening, pectin polysaccharides and loosely bound matrix polysaccharides were solubilized and the release of xylosyl and galactosyl residues occurred. Cell wall changes in galactosyl residues after 1-MCP treatment were comparable to those of untreated fruit but 1-MCP treated fruit did not soften completely. The changes in the cell wall fractions containing xylosyl residues in 1-MCP treated fruit showed less solubilization and a higher association of xylosyl residues with the pectic polysaccharides. The results indicated that normal modification of cell wall xylosyl components during ripening did not occur following 1-MCP treatment at the color-break stage, this was associated with the failure of these fruit to fully soften and a selective suppression of endoxylanase activity. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Papaya flesh color is the result of the accumulation of carotenoids in fruit cell chromoplasts, primarily lycopene in red flesh and b-carotenoids in yellow flesh, which provide antioxidant activity and vitamin A nutrition, respectively. Red flesh papaya softens faster and has a shorter shelf life, but some consumers prefer red flesh papaya, often called "strawberry papaya" in the market. An understanding of the gene expression changes that have altered the carotenoid pathway in red fleshed fruit provides us with an approach to further alteration of the fruit nutritional value. In addition the identification of the genes controlling flesh color will generate new tools for papaya improvement and facilitate comparative genomic research in fruit crops. Clarifying on a global scale which genes are expressed during ripening will enable us to understand how developmental processes in plants have evolved to enhance the potential for seed dispersal and fruit ripening. This project will provide a greater understanding of the changes in regulatory function and expression of orthologs involved in fruit development. Our results support a role for endoxylanase in normal papaya fruit softening and its suppression by 1-MCP lead to a failure to fully soften. Normal papaya ripening related softening was dependent upon the expression and activity of endoglucanase, beta-galactosidase and endoxylanase. An understanding of the molecular basis for fruit ripening has potential applications to modify ripening of a wide variety of fruits to improve postharvest characteristics and fruit quality and reduce postharvest losses.

Publications

  • Andrea L. Blas, Ray Ming, Zhiyong Liu, Olivia J. Veatch, Robert E. Paull, Paul H. Moore, Qingyi Yu. 2010. Cloning of papaya chromoplast specific lycopene alpha-cyclase, CpCYC-b, controlling fruit flesh color reveals conserved microsynteny and a recombination hotspot. Plant Physiology 152, 2013-2022.
  • Thumdee, Siwaporn, Ashariya Manenoi, Nancy J. Chen, Robert E. Paull. 2010. Papaya Fruit Softening: Role of Hydrolases. Tropical Plant Biology 3, 98-109.
  • Wai C, Ming R, Moore P, Paull R, and Yu Q. 2010. Development of Chromosome-specific Cytogenetic Markers and Merging of Linkage Fragments in Papaya. Tropical Plant Biology 3, 171-181.


Progress 10/01/08 to 09/30/09

Outputs
OUTPUTS: The complication of linkage group 2 was resolved by high density genetic mapping of the papaya genome using sequence-tagged co-dominant microsatellite markers. The current high density genetic map consists of nine major linkage groups and three minor linkage groups. Our revised objective 2 is to assign the three minor linkages to chromosomes defined by major linkage groups. Our molecular cytogenetic mapping results placed the three minor linkage groups 10, 11, and 12 to chromosomes defined by major linkage groups 8, 9, and 7 respectively. The papaya chromosome 1 contains the male-specific Y chromosome region (MSY), which controls sex in papaya. We selected 12 SSR markers along the papaya chromosome 1, spanning 121cM with average distance between neighbor markers at 10cM. We have analysed the papaya genome data base and papaya has the same or fewer predicted genes than Arabidopsis in most phytohormone categories except for jasmonic acid where papaya has more genes. The findings from this domain analysis supports our proposal that papaya has fewer genes, is more ancestral, and the signaling pathways and controls are likely to be less complex than other ripening fruit, and Arabidopsis which has undergone genome duplication. The QTL for the slow-ripening trait in papaya is located on linkage group #1 and is predicted to contain about fifty genes on supercontig 21. Eleven of these predicted genes showed little or no expression at the mature green or the 35% yellow stage of ripening. Seven genes were up-regulated more than two-fold, twenty-five genes down-regulated and the rest showed less than two-fold change between stages. The seven up-regulated genes included two unknowns, one dehydrogenase and aMajor Facilitor Superfamily (MFS) domain containing gene. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
An accurate chromosome map is an essential resource for genome sequence assembly, genetic and physical mapping of targeted genes, and papaya improvement via genetic engineering and gene manipulation. With the completion of the papaya genome sequencing project, genomic resources are available to construct a sequence-tagged genetic map and linking the genetic map to chromosomes by florescent in situ hybridization of strategically selected DNA markers. The integrated genetic, physical, and chromosome map will be an enormously useful tool for the papaya research community and ultimately benefit the papaya growers with improved papaya cultivars and products. Clarifying on a global scale which genes are expressed during ripening will enable us to understand how developmental processes in plants have evolved to enhance the potential for seed dispersal and fruit ripening. This project will provide a greater understanding of the changes in regulatory function and expression of orthologs involved in fruit development.

Publications

  • Huang, Chao-Chia, Paull, Robert E. 2009 The responses of oncidium cut flowers to ethylene and 1-MCP. Journal of Taiwan. Agriculture Research 58(1):1- 6
  • Wang, Ming Li., G. Uruu, L. Xiong, X. He, C. Nagai, K. T. Cheah, J. S. Hu, G.-L. Nan, B. S. Sipes, H. J. Atkinson, P. H. Moore, K. G. Rohrbach, R. E. Paull. 2009. Production of transgenic pineapple plants via adventitious bud regeneration. In Vitro Cellular and Developmental Biology 45, 112-121
  • Chen, Nancy J., Paull, R.E., Chen, C.-.C. and Saradhuldhat, P. 2009. Pineapple Production for Quality and Postharvest Handling. Acta Hort. (ISHS) 822: 253-260.
  • Blas, Andrea L., Qingyi Yu, Cuixia Chen, Olivia Veatch, Paul H. Moore, Robert E. Paull, Ray Ming. 2009 Enrichment of a papaya high-density genetic map with AFLP markers. GENOME 52: 716-725.
  • Chen, Nancy J., Wall, Marisa M., Paull, Robert E., Follett, Peter A. 2009. Variation in 'Sharwil' Avocado Maturity during the Harvest Season and Resistance to Fruit Fly Infestation HortScience 44: 1655-1661
  • Paull, Robert E., Beth Irikura, Ping Fang Wu, Helen Turano, Nancy Jung Chen, Andrea Blas John K. Fellman, Andrea R. Gschwend, Ching Man Wai, Qingyi Yu, Gernot Presting, Maqsudul Alam, Ray Ming, 2008. Fruit Development, Ripening and Quality Related Genes in the Papaya Genome. Tropical Plant Biology 1, 246-277
  • Hollingsworth, Robert. G., G. A. Chastagner, N. J. Reimer, D. E. Oishi, P. J. Landolt, & R. E. Paull, 2009. Use of shaking treatments and pre-harvest sprays of pyrethroid insecticides to reduce risk of yellow jackets and other insects on Christmas trees imported into Hawaii. Journal of Economic Entomology 102 (1) 69-78.


Progress 10/01/07 to 09/30/08

Outputs
OUTPUTS: The red macro-algae, when stored overnight at 2C and 10C, thalli became limp and entirely pinkish-red indicating possible chilling injury. The optimal storage temperature was between 15 and 17 oC in the dark. Treating limu with hot sea water at 42C for 5 min was beneficial in maintaining appearance and extended postharvest life 40 to 60%. Storage at 15C and either or both submerged in seawater or treated at 42C for 5 min depending upon species, showed potential at increasing postharvest life of red seaweed. The sensitivity of cut flowers and foliage to irradiation used for insect disinfestation varies from species to species and to a lesser extent variety to variety. Flowers with low sensitivity to 250 Gy of electron beam irradiation were Red ginger and Bird-of-Paradise inflorescences, and Oncidium sprays. Medium sensitive flowers were Dendrobium, Protea hybrid Pink Ice and heliconia Red Stricta. Flowers that showed high sensitivity to 250 Gy were Heliconia Keanae, Beehive ginger, Barbatus ginger, and Indian head ginger inflorescences. Leatherleaf fern and baby eucalyptus foliage showed little or no sensitivity to irradiation. Papaya the Slow ripening Line 4-16 were harvested and stored at 10C were more susceptible to postharvest disease than non-stored fruit as the length of storage time increased. Decay rate increased dramatically from 12% to near 40% when storage period increased from 2 to 4 weeks. Fruit stored at 10C colored faster (7 to 8 days) when removed from 10C and ripened at ambient temperature. The 556 primer sets for SSR markers were used to screen for hard and soft papaya fruit QTLs. Of these, 44 primers were selected at about 10 cM intervals throughout the 12 linkage groups. A potential QTL has been isolated and genes in this region are now being evaluated. The most significant outputs are the construction of a sequence tagged high density genetic map of papaya and the development of 11,976 SSR markers. This high density genetic map was used for integration of genetic and physical maps and for the papaya genome sequence assembly. About 92% of the markers in the genetic map were in the assembled genome. This genetic map was published in Genetics and the information is available to the public. The sequence information of the 11,976 SSR markers will be published soon and available to the scientific community. A combined total of 11,976 pairs of SSR primers were developed from the following DNA sequence sources: 9,955 SSRs from papaya whole genome shotgun sequence reads of SunUp, including 9,216 from non-redundant individual sequence reads and 739 from assembled contig sequences; 2,021 SSRs from 1979 BAC end sequences and 42 selected subclones of papaya BACs. A total of 711 markers, including 710 SSR markers and the morphological marker fruit flesh color, were mapped to 12 linkage groups (LGs), including nine large and three short that collectively span 1068.9 cM with an average distance of 1.5 cM between adjacent markers. The nine major linkage groups, which correspond to nine chromosomes in the papaya genome, covered a total length of 993.5 cM (92.7%) with 685 mapped loci (96.5%) at an average marker density of 1.4 cM. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Papaya softening is a complex event that involves many cell wall hydrolases, such as endoxylanase, b-xylosidase, b-galactosidase, and endoglucanase. These hydrolases may play their roles in concert, to provide the unique texture of a particular fruit. Endoxylanase appears to play a major role in papaya softening. A regulated decline in mesocarp pH during ripening may regulate these hydrolases and impact papaya mesocarp softening. In addition the potential slow-ripening QTL, if we can isolate it to specific genes, could have wider application in modifying fruit ripening. A sequence tagged high density genetic map of papaya has been developed with 11,976 SSR markers. This high density genetic map was used for integration of genetic and physical maps and for the papaya genome sequence assembly. About 92% of the markers in the genetic map were in the assembled genome. This genetic map was published in Genetics and the information is available to the public.

Publications

  • Cuixia Chen, Qingyi Yu, Shaobin Hou, Yingjun Li, Moriah Eustice, Rachel L. Skelton, Olivia Veatch, Rachel E. Herdes, Lauren Diebold, Jimmy Saw, Yun Feng, Wubin Qian, Lee Bynum, Lei Wang, Paul H. Moore, Robert E. Paull, Maqsudul Alam, Ray Ming. 2007 Construction of a Sequence-Tagged High Density Genetic Map of Papaya for Comparative Structural and Evolutionary Genomics in Brassicales. Genetics 177: 2481-2491
  • Sangwanangkul, P., P. Saradhuldhat and R. E. Paull. 2008. Survey of Tropical Cut Flower and Foliage Responses to Irradiation. Postharvest Biology & Technology 48: 264-271
  • R. E. Paull and Nancy Jung Chen. 2007. Postharvest handling and storage of the edible red seaweed Gracilaria. Postharvest Biology and Technology 48: 302-308.
  • R. Ming, S. Hou, Y. Feng, Q. Yu, A. Dionne-Laporte J.H. Saw, P. Senin, W. Wang, B. V. Ly, K.L.T. Lewis, S.L. Salzberg, L. Feng, M.R. Jones, R.L. Skelton, J.E. Murray, C. Chen, W. Qian, J. Shen, P. Du, M. Eustice, E. Tong, H. Tang, E. Lyons, R.E. Paull, T.P. Michael, K. Wall, D. Rice, H. Albert, M.Li Wang, Y.J. Zhu, M. Schatz, N. Nagarajan, R. Agbayani, P. Guan, A. Blas, C.Man Wai, C.M. Ackerman, Y. Ren, C. Liu, J. Wang, J. Wang, J.K. Na, E.V Shakirov, B. Haas, J. Thimmapuram, D. Nelson, X. Wang, J.E. Bowers, A. R. Gschwend, A.L. Delcher, R. Singh, J.Y. Suzuki, S. Tripathi, K. Neupane, H. Wei, B. Irikura, M. Paidi, N. Jiang, W. Zhang, G. Presting, A. Windsor, R. Navajas-Perez, M. J. Torres. F. A. Feltus, B. Porter, Y. Li, A.M. Burroughs, M.C. Luo, L. Liu, D.A. Christopher, S.M. Mount, P.H. Moore, T. Sugimura, J. Jiang, M.A. Schuler, V. Friedman, T. Mitchell-Olds, D.E. Shippen, C.W. dePamphilis, J.D. Palmer, M. Freeling, A. H. Paterson, D. Gonsalves, L. Wang, M. Alam. 2008. Genome of the transgenic tropical fruit tree papaya (Carica papaya Linnaeus). Nature 452: 991-996.
  • Theeranuch Jaroenkit, Nancy Jung Chen and Robert E. Paull. 2008. Nectar Secretion, Mucilage Production and Mold Growth on Bird-of-Paradise Inflorescences. Postharvest Biology and Technology 49, 431-435
  • Janick, J. And R. E. Paull. Editors. 2008. The Encyclopedia of Fruits and Nuts. CABI Publishing, Wallingford, United Kingdom. 954 pp
  • Paull, Robert. E., Kelvin Sewake. 2008 Postharvest Physiology and Handling of Dendrobium Flower Sprays. Proceeding of the 4th Asia Pacific Orchid Conference, Chiang Mai, Thailand, 1992 January 25-26. p69-80.
  • Paull, R. E. And N. J. Chen. 2008. Global trends in marketing and postharvest handling research of horticultural produce. Pp 3-11. Proceeding of the National Horticulture Conference 2007, March 13-15, Johor Bahru, Malaysia. Editors Ahmad Sapii et al.


Progress 10/01/06 to 09/30/07

Outputs
Hydrolases have been detected during fruit softening and may play an important role in papaya softening. Variation in softening of papaya varieties and the incomplete softening of papaya treated with 1-methylcyclopropene (1-MCP) present an opportunity to determine the factors causing fruit softening. Mesocarp of Line 8 and Sunset papayas showed significant losses in cell wall mass during normal softening, but papaya did not lose the mass when softening was restrained by 1-MCP treatment. Solubilizations and dissociations of pectic polysaccharides and loosely bound matrix polysaccharides that consisted of xylosyl and galactosyl residues at high concentration were noticeable during normal softening. Although the major changes in galactosyl components of cell wall in 1-MCP-treated papaya were comparable to those in control papaya, the 1-MCP-treated papaya did not soften completely. The comparison of cell wall modification between 1-MCP-treated papaya and control papaya confirmed that the modification of xylosyl component of cell wall was involved in the abnormal papaya softening when treated with 1-MCP. Activities of b-galactosidase, endoglucanase, endoxylanase, and b-xylosidase were correlated with fruit softening. When softening was modified by 1-MCP treatment, a rise in activity of these hydrolases was delayed; but only endoxylanase activity was completely suppressed throughout ripening. During softening, a change in mesocarp pH was implicated. Mesocarp pH of Line 8 and Sunset papayas declined when fruit started to soften with no reduction in 1-MCP-treated papaya. Applied low pH affected mesocarp firmness, but the effect varied with the stage of fruit ripeness and specific fruit tissue. Papaya glucose uptake during fruit development was studied by comparing glucose uptake of mesocarp slices between two cultivars, Sunset and UH801 (low sugar line). Sunset papaya fruit, though one third the weight of UH801, had higher total soluble solids, total sugar, and dry weight than UH801. The pattern of glucose uptake by Sunset papaya flesh discs was divided into three fruit growth phases during fruit maturation. Uptake was initially low during the first phase, 90-110 days from anthesis, and the last phase, after 132 days from anthesis and high 95-130 days after anthesis. The maximum glucose uptake in Sunset was found at 118 DAA and ranged from 1,367 and 2,140 mmol/mg protein/h. The first Carica papaya hexose transporter (CpHT1) was cloned and consisted of 3,218 bp with four exons and three introns. The full length CpHT1 mRNA was predicted to be 1,732 bp and encoded a 523 amino acids long peptide. The predicted polypeptide was estimated to be 57.48 kDa and contained 12 transmembrane helices with both amino and carboxyl terminals located in the cytosol.

Impacts
Papaya softening is a complex event that involves many cell wall hydrolases, such as endoxylanase, b-xylosidase, b-galactosidase, and endoglucanase. These hydrolases may play their roles in concert, to provide the unique texture of a particular fruit. Endoxylanase appears to play a major role in papaya softening. A regulated decline in mesocarp pH during ripening may regulate these hydrolases and impact papaya mesocarp softening. Papaya final sugar content (sweetness) is dependent upon apoplastic unloading of the phloem just prior to harvest. Apoplastic unloading is dependent upon invertase and hexose transporter activity. Papaya hexose transporter appeared to be an energy-dependent cotransporter. Hexose transporter activity was detected but glucose uptake did not appear to correlate with papaya sugar accumulation. Hence, the role of invertase in phloem unloading may be a more important factor in determining fruit sugar levels at harvest. The first Carica papaya hexose transporter (CpHT1) has been cloned and now provides us with the opportunity to directly determine the roles of invertase and hexose in papaya fruit sugar accumulation.

Publications

  • Chen, N. J., A. Manenoi, R. E. Paull. 2007. Papaya postharvest physiology and handling - problems and solutions. Acta Horticulturae 740:285-294.
  • Sangwanangkul, P., R. E. Paull. 2007. The role of hexose transporter in sugar accumulation of papaya fruit during maturation and ripening. Acta Horticulturae 740:313-316.
  • Thumdee, S., A. Manenoi, R. E. Paull. 2007. Activity of papaya fruit hydrolases during normal and modified ripening. Acta Horticulturae 740:317-322.
  • Manenoi, A. R. E. Paull. 2007. Effect of 1-methylcyclopropene (1-MCP) on papaya fruit ripening. Acta Horticulturae 740:323-326.
  • Manenoi, A., E. R. V.Bayogan, S. Thumdee and R. E. Paull. 2007. Utility of 1-Methylcyclopropene as a Papaya Postharvest Treatment. Postharvest Biology and Technology 44:55-62
  • Saradhuldhat, P., R. E. Paull. 2007. Pineapple organic acid metabolism and accumulation during fruit development. Scientia Horticulturae 112:297-303
  • Manenoi, A., R. E. Paull. 2007. Papaya fruit softening, endoxylanase gene expression, protein and activity. Physiologia Plantarum 131:470-480.


Progress 10/01/05 to 09/30/06

Outputs
Papaya fruit treated with various concentrations of 1-MCP for 24 h were firmer and the time to reach the edible ripe stage was longer than the non-treated control. The onset of ethylene production and the rise in the respiration rate was delayed and suppressed in 1-MCP-treated fruit. When ripened at 22C, 1-MCP-treated color break fruit had a delay of about 7 days in softening and skin color development but only a slight effect on total soluble solids and weight loss. However, papaya treated with 1-MCP at the color break stage were firmer and showed a rubbery texture at the ripe stage. Fruit treated with 1-MCP when more than 25% skin yellow ripened normally. Storage of 10% yellow fruit at 10C for 7 days before or after 1-MCP treatment had no effect on 1-MCP softening response. It was concluded that papaya fruit treated with 1-MCP when more than 25% ripe had a delay in softening that may have commercial utility. During papaya fruit ripening, an endoxylanase is expressed and the extracted enzyme is active in vitro and may play a role in the softening process. Three papaya varieties: Line 8, Sunset, and Line 4-16, differ in softening pattern and showed similar parallel relationships during ripening and softening in endoxylanase expression, protein level and activity. When fruit of each of the three papaya varieties started to soften, the level of endoxylanase gene expression increased and this increase was highly related to endoxylanase protein accumulation and activity. Although breadfruit produce low ethylene during ripening, they were highly responsive to exogenous ethylene and 1-MCP did block ethylene effect on breadfruit softening. Dipping fruit in 500 ppm Ethephon for 5 min was efficient to hasten ethylene production and respiration, accelerated fruit softening, and shortened shelf life. The ACC synthase gene has been fully sequenced. A combination treatment of 1-MCP, and perforated PE bag or coated with canola oil, storage at 17C showed twice longer in the days to soften and shelf life (10-11 days) compared to when treated with 1-MCP alone (4 days), or when storage at 17C alone (4 days). Fruit treated with these combination treatments showed an acceptable quality when full ripe. The sequence has high homology (similarity), from 78 to 80% with ACC synthase isolated in pear, apple and papaya. The translated protein also showed high homology (77 to 78%) to the same species. The protein has a transferase binding domain. Irradiation sensitivity of cut flowers and foliage varies from species to species and to a lesser extent variety to variety. Flowers with low sensitivity to 250 Gy of electron beam irradiation were Red ginger and Bird-of-Paradise inflorescences, and Oncidium sprays. Medium sensitive flowers were Dendrobium Royal purples, Protea hybrid Pink Ice and heliconia Red Stricta. White dendrobium (UH 306) was significantly more sensitive than the Pink (UH 232) to irradiation. Pretreatment of UH 306 with 1-MCP extended the vase life of dendrobium sprays and mitigated the effects of irradiation on dendrobium vase life. The 1-MCP treatment can be carried out in the plastic lined carton during shipment to the irradiation plant.

Impacts
Papaya can be treated with 1-MCP when more than 25% ripe and there is a delay in softening that may have commercial utility. The fruit can be treated with 1-MCP in a polyethylene lined cardboard shipping carton during transport removing the need for special treatment chambers. The 1-MCP treated color break fruit that had the rubbery texture showed suppressed endoxylanase gene expression, protein and enzymatic activity suggesting a role in normal fruit softening. Breadfruit produce low ethylene during ripening, they highly responded to exogenous ethylene and 1-MCP did block ethylene effect on breadfruit softening. A combination treatment of 1-MCP, and perforated PE bag or coated with canola oil, storage at 17C showed twice longer in the days to soften and shelf life (10-11 days) compared to when treated with 1-MCP alone (4 days), or when storage at 17C alone (4 days). Irradiation sensitivity of cut flowers and foliage varies from species to species and to a lesser extent variety to variety. This variation in sensitivity determines whether irradiation can be used for insect disinfestation. Flowers with low sensitivity to 250 Gy of electron beam irradiation were Red ginger, Bird-of-Paradise and Oncidium sprays. Medium sensitive flowers were Dendrobium Royal purples, Protea hybrid Pink Ice and heliconia Red Stricta. Flowers that showed high sensitivity to 250 Gy were Heliconia Keanae, Beehive ginger, Barbatus ginger and Indian head ginger inflorescences. Heat and 1-MCP treatment before irradiation reduce the sensitivity for some ornamentals.

Publications

  • Paull, R. E. and N. J. Chen. 2005. Papaya Mechanical Injury. 41st Annual Hawaii Papaya Industry Association Conference, Hilo, Hawaii. September 23rd & 24th 2005. Pp. 28-31.
  • Ming-Li Wang, Henrik H. Albert, Ray Ming, Paul H. Moore, Robert E Paull, 2006. Cloning Of Organ-Specific Genes from Papaya Using cDNA-AFLP. Abstract for Plant and Animal Genome XV Conference, January 13-17, 2007. San Diego, California
  • Brown, P., T. Lumpkin, S. Barber, E. Hardie, K. H. Kraft, E. Luedelin, T. Rosenstock, K. Tabaj, D. Clay, G. Luther, R. E. Paull, S. Weller, F. Youseffi, M. Demment. 2005. Global Horticulture Assessment. ISHS Scripta Horticulturae Number 3. 134pp
  • Paull, R. E. and N. J. Chen. 2006. Limu after harvest: maintaining quality and extending the shelf life of seaweed species (Gracileria spp.) popular in Hawaii. Regional Notes Center for Tropical and Subtropical Aquaculture 17 (2) 4-7.
  • Chen, N. J., and Paull, R. E. 2006. Applicacoes do biotechnologia na pos-colheita de frutos: progressos e limitacoes. Proceeding of the XIX Congresso Brasileiro de Fruticultura, Cabo Frio, RJ. Brazil, 17 to 22 September. p 87-94.


Progress 10/01/04 to 09/30/05

Outputs
Rainbow papaya fruit at the color break stage (<10% skin yellowing) were treated with 100 nL/L MCP for 12 hrs and stored at 21 to 22C. The onset of ethylene production and the rise in the respiration rate was delayed and suppressed in MCP-treated fruit. MCP-treated fruit had a significant delay about 7 days in softening and skin color development but little effect on total soluble solids (TSS) and weight loss. Papaya glucose uptake during fruit development was studied by comparing [14C] glucose uptake of mesocarp slices between two cultivars, Sunset and UH801 (low sugar line) in two seasons. Sunset papaya fruit, though one third the weight of UH801, had higher total soluble solids (TSS), total sugar, and dry weight (DW) than UH801. Both cultivars reached the color break stage at the same time, 125 days after anthesis (DAA), but flesh color, TSS and dry weight of Sunset fruit began to increase 111 DAA, one to three weeks before UH801. Glucose uptake in Sunset fruit was lower than for UH801. Hexose uptake was initially low during the first, 90-97DAA (2003) and 90-111DAA (2004), and last phrase, after 132DAA for both years and higher 97-132DAA and 111-132DAA in 2003 and 2004, respectively. The maximum glucose uptake in Sunset was found at 118DAA in both years 1,367 and 2,140 mol mg protein-1h-1, respectively. Papaya fruit softening is thought to be the result of cell wall degradation. The activity of -galactosidase, PME and glucanase was related to fruit softening. Because the activity of PG was very low, its pattern varied and was not related to the softening patterns. The activity of endo-xylanase was related to the softening only in the untreated fruit but not in the MCP-treated fruit. The endo-xylanase activity of MCP-treated fruit was highly suppressed throughout the fruit softening. The failure of MCP-treated papaya to soften completely and have a rubbery texture may have been caused by a suppression of endo-xylanase activity. Developmental changes in the activities of pineapple acid related enzymes citrate synthase (CS), aconitase (ACO), phosphoenolpyruvate carboxylase (PEPC), malate dehydro-genase (MDH) and malic enzyme (ME) were determined during fruit growth and development. CS activity greatly increased a week before harvest and the increase was coincident with the peak in the citric acid content of the high acid clone. Increased ACO activity was coincident with a sharp reduction in organic acid in the low acid fruit just before harvest. The activities of PEPC, MDH and ME did not directly relate to the changes in fruit acidity. The changes in fruit potassium were significantly correlated with the changes in fruit acidity in both clones during fruit growth and development, although the potassium concentrations were similar between clones at harvest. The optimal storage temperature for Gracilaria salicornia is between 15C to 17C in the dark. A 2 minute and 60 minutes postharvest dips in calcium, ammonium and nitrate did not extend shelf life. Heat shock treatments seem to extend storage life. It is also possible that heating may facilitate the effectiveness of calcium application after harvest.

Impacts
Papaya, when treated with MCP at the color break stage, showed a rubbery texture during ripening while fruit treated with more than 30% skin yellowing ripened normally. The disruption in softening that lead to the rubbery texture may be due to selective loss of cell wall hydrolyases. Papaya hexose transporter appeared to be an energy-dependent cotransporter involved in sugar accumulation. Hexose transporter activity did not appear to correlate with papaya sugar accumulation. Hence, the role of invertase in phloem unloading may be a more important factor determining fruit sugar levels at harvest. Acid accumulation in pineapple fruit during fruit growth and development was mainly due to changes in citric acid concentration. The activities of citrate synthetase and aconitase and the fruit potassium content participated in the regulation of pineapple fruit acid metabolism and accumulation. Treating limu with hot sea water at 42C for 5 minutes was beneficial in maintaining limu appearance and extended postharvest life.

Publications

  • Paull, R.E., Jaroenkit, T. and Chen, N.J. 2004. Postharvest handling, packaging and shipping of tropical ornamentals. Proceeding of the Hawaii Floriculture Conference, Kahului, Hawaii, March 25. CTAHR Proceedings 2005 April, P-04/05.
  • Silva, J.A., Hamasaki, R., Paull, R., Ogoshi, R., Bartholomew, D.P., Fukuda, S., Hue, N.V., Uehara, G. and Tsuji, G.Y. 2005. Effects of Lime, Gypsum, and Basaltic Dust on the Calcium Nutrition and Fruit Quality of Pineapple. Acta Horticulturae.


Progress 10/01/03 to 09/30/04

Outputs
During early pineapple fruit growth, titratable acidity was higher in the low acid than the high acid cultivar. Acidity increase paralleled fruit development and peaked two weeks before harvest, then declined. In the high acid cultivar, acidity continued to increase to the commercial harvest stage. Total soluble solid (TSS) of both high and low acid cultivars increased during fruit growth. The change in acidity level near harvest in the low acid cultivar was correlated to higher aconitase and citrate dehydrogenase. No reliable way is available to predict the occurrence of natural flowering of susceptible pineapple hybrids in Hawaii. Spray application of aviglycine reduced natural flowering of pineapple from 64% in the control to 23% in the best treatment and the result was highly significant. Application of aviglycine through the drip irrigation system as a drench treatment did not significantly reduce natural flowering. Aviglycine inhibits natural flowering of a low-acid cultivar of pineapple and spray application provides the best control. Papaya fruit treated with 1-MCP for 24 h remained firmer and took a longer time to reach the edible ripe stage. Treated color break fruit tended to have better quality and less severe external blemishes/injuries. The failure of MCP treated color break fruit to soften fully, while fruit that had 30% or more yellow skin at treatment apparently ripened normally places limitation on the commercial application of MCP to delay papaya ripening. Freezing and chilling injury are frequent occurrence when Hawaiian tropical flowers and foliage are shipped during winter. We have been evaluating a number of different carton types as to their effective in comparison to the current winterized carton. Four packs gave some protection, the current winterized pack, the pack with newspaper, foam board, and the pack with heater included. The bubble insulated wrap offer little in the way of freezing protection. The cartons with heating pads on the bottom of the box did not yield a temperature profile as high as the one from box with foam board, nonetheless the condition of the tropical mix in the heated box were as good as or better than those in the box with foam board. Among all the anthurium flowers tested, Midori was the most chilling sensitive. Marian Seefurth and Tropical ice were a little more chilling tolerant, while Lehua red was rather chilling resistant. The heated pack was as good as the foam board pack and the newspaper pack, it would provide 5 to 6 hours of protection. Bird-of Paradise have two problems during handling: relatively short postharvest life and mold growth during shipping. Mold can be induced by covering the flowers in a plastic bag. Using this assay we were able to show that mold growth did not occur on the nectar or slime as originally expected but mold grew on the anther of the first flower open. The anther also had to be inoculated in the field. No wash treatment was fully successful in eliminating the growth though water washes of the anther were effective in reducing mold growth.

Impacts
The pineapple fruit metabolism involved in acid accumulation has not been reported. The only similar comparison research was done on sweet and sour limes. The analyzed results suggest that enzyme activity and ion accumulation may be having the greatest effects on acidity. The papaya project focus is both non-genetically engineered natural slow ripening and genetically engineered papaya lines that we have developed. The better selections reach the edible soft stage about 21 days after skin color break, versus 10 to 12 days for the current commercial varieties. A delay of this magnitude in softening could alter both fruit susceptibility to fruit fly and disease, and increase shelf life. Fruit having slower softening during ripening would allow greater flexibility in harvest scheduling. Coupled to the change in harvest frequency, fruit allowed to stay on the plant for a longer period would accumulate more sugars and be sweeter. Packer/shipper would have fruit that can be more accurately graded as to skin color thereby avoiding the checkerboard pattern seen in cartons. Consumers would receive a higher quality product.

Publications

  • Kays, S.J. and Paull, R.E. 2004. Postharvest Biology. Exon Press, Athens, Georgia.
  • Ackerman, C.M., Yu, Q., Moore, P.H., R.E. Paull, Steiger, D.L. and Ming, R. 2004. Cloning and characterization of a papaya SUPERMAN ortholog. Plant Biology 2004 Meeting, Lake Buena Vista, Florida, July 24 to 28.
  • Paull, R.E. and Chen, N.J. 2004. Agronegocio da Lichia nos EUA - Situacao Atual e Perspectivas Futuras (Litchi Industry in the USA - Present and Future Trends). Workshop Proceedings Seminario Internacional De Lichia no Brazil.
  • Paull, R.E. and Chen, N.J. 2004. Manejo Pos-colheita e Armazenamento de Litchia (Postharvest Handling and Storage of Litchi). Workshop Proceedings Seminario Internacional De Lichia no Brazil.
  • Ackerman, C.M., Yu, Q.Y., Moore, P.H., Paull,R.E., Steiger, D.L. and Ming, R. 2004. Cloning and characterization of a Superman ortholog in polygamous papaya. (Abstract) International Plant and Animal Genome Conference.


Progress 10/01/02 to 09/30/03

Outputs
Pineapple. We have concentrated on determining the relationship between weather during fruit growth on fruit acidity and sugar accumulation. The low acid variety had higher acidity during the fruit mid-growth stage and peaked sooner than the canning variety. After the peak the acidity declined in both variety but since the low acid variety peaked sooner it had declined further by harvest than the canning variety. Sugar accumulation was similar for both low acid and canning varieties. The D-10, however, did not accumulate as much sugar as the canning variety. Papaya. Papaya (Carica papaya L.) softening during fruit ripening is correlated to the activity of a 32.5-kDa endoxylanase (CpaEXY1) purified 45,871 fold on enzymatic activity and to homogeneity by SDS electrophoresis. CpaEXY1 codes for a 584 amino acids 64.96-kDa protein. The N-terminal 27 amino acids and is a predicted secretory signal peptide. A predicted carbohydrate binding module is found between amino acids #60 and #182. CpaEXY1 is developmentally expressed during fruit ripening and the expression correlates with the variation in softening patterns of different varieties. We have sixteen PCR positive and eight other selected lines that are putative endoxylanase antisense lines. We have two non-genetically engineered natural slow ripening papaya lines. The initial work focused on these slow ripening lines was to reduce the heat induced sterility found in the original selection by backcrossing to Sunset. Slow softening progeny were selected along with early fruiting. The better selections reach the edible soft stage about 21 days after skin color break, versus 10 to 12 days for the current commercial varieties. Floriculture. The present results confirm that wet handling of the blooms is not necessary to maintain vase life compared to dry handling to the packing shed. MCP at the concentrations and duration of application tested had no deleterious effects on the blooms. The vase life of bird of paradise harvested when the bract-like boat shows a distinct orange bulge was not improved by a Chlorox pulse, citric acid and sugar, and 1-MCP. Blooms treated with 0.5 ul l-1 1MCP did not consistently improve floret opening. Increasing the sucrose concentration from 10 to 20% with 8-HQC, citric acid and sucrose resulted in a greater increase in vase life with flowers at the tight bud blooms and those with distinct orange color showing or as bulge on the bracts edge. We confirmed the positive response of a dip 100 ppm BA on anthurium vase life. The spathe gloss and spathe blueing at 15 DAT in all the cultivars show the potential of TDZ in delaying leaf senescence in the cultivars Leilani, Kalapana and Marian Seefurth in comparison with the control. Only Rose Mink pulsed with 7.5% glucose gave a longer leaf postharvest life of 9.2 days when 25% of the leaves showing at least 10% leaf blackening. All the treatments showed shorter leaf postharvest life relative to visual quality deterioration of the flower head. The vase lives of various protea cultivars varied significantly with Rose Mink having the longest vase life of 6 days based on leaf blackening.

Impacts
The pineapple fruit metabolism involved in acid accumulation has not been reported. The only similar comparison research was done on sweet and sour limes. The analyzed results suggest that enzyme activity and ion accumulation may be having the greatest effects on acidity. The papaya project focus is both non-genetically engineered natural slow ripening and genetically engineered papaya lines that we have developed. The better selections reach the edible soft stage about 21 days after skin color break, versus 10 to 12 days for the current commercial varieties. A delay of this magnitude in softening could alter both fruit susceptibility to fruit fly and disease, and increase shelf life. Fruit having slower softening during ripening would allow greater flexibility in harvest scheduling. Coupled to the change in harvest frequency, fruit allowed to stay on the plant for a longer period would accumulate more sugars and be sweeter. Packer/shipper would have fruit that can be more accurately graded as to skin color thereby avoiding the checkerboard pattern seen in cartons. Consumers would receive a higher quality product.

Publications

  • Bunsiri, A., Ketsa, S. and Paull, R.E. 2002. Phenolic metabolism and lignin synthesis in damaged pericarp of mangosteen fruit after impact. Postharvest Biology and Technology. 29:61-71.
  • Zhou, L.L., Chen, C-C, Ming, R., Christopher, D.A. and Paull, R.E. 2003. Apoplastic invertase and its enhanced expression and post translation control during fruit maturation and ripening. Journal of the American Society for Horticulture Science. 128:628-635.
  • Chen, N.J. and Paull, R.E. 2003. Endoxylanase expressed during papaya fruit ripening: purification, cloning and characterization. Functional Plant Biology. 30:433-441.
  • Jaroenkit, T. and Paull, R.E. 2003. Postharvest handling of Heliconia, Red Ginger, and Bird-of-Paradise. HortTechnology. 13:259-266.
  • Paull, R.E. 2002. Advances in Postharvest Technology for Tropical and Subtropical Fruits. pp157-167. Proc. International Technical & Trade Seminar on Tropical & Subtropical Fruits. 2001 July 2-4, Kuala Lumpur, Malaysia.
  • Paull, R.E. and Chen, N.J. 2003. Endoxylanase expressed during papaya fruit ripening: Purification, cloning and characterization. Abstract #1317. Plant Biology 2003, Honolulu, Hawaii. July 25 to July 30.
  • Yu, Q., Ackerman, C., Ming, R., Moore, P., Albert, H. and Paull, R.E. 2003. Cloning and characterization of flower development genes in papaya. Abstract #508. Plant Biology 2003, Honolulu, Hawaii. July 25 to July 30.


Progress 10/01/01 to 09/30/02

Outputs
Low acid pineapple hybrids (D-10, CO-2) show less variation in titratable acidity that published for canning varieties. Gummosis was a major disorder found especially in the March to May period due to insect feeding. All papaya varieties except 4-16, ripened in about 6 days, while 4-16 ripened in about 12 days at room temperature. Kapoho had higher TSS (14.12%) than SunUp (13.36%) and Rainbow (13.15%), while 4-16 had a slightly lower TSS (11.93%) at the soft eating stage. The firmness of Rainbow, Kapoho and SunUp declined to less than half after 3 days storage, 4-16 was firmer and slowly softened to the eating stage after 21 days of storage. The preliminary conclusions for the experiments reported are: a) Papaya line 4-16 showed slower ripening than Rainbow, Kapoho, and SunUp and was ready to eat in 12 days versus 6 days from the mature green stage for the other varieties. b) All papaya varieties can be held in storage (8-10C) at the color break stage for up to 2 weeks, longer storage times leads to a significant loss of quality and disease incidence. c) MCP-treated Rainbow and 4-16 had slower ripening than non-treated fruit. However, all MCP-treated had more rubbery flesh than non-treated fruit. e) MCP-treated fruit (at the color break stage) had a increased respiration rate sooner than non MCP-treated fruit. There was no difference in the respiration rate between MCP-treated and non-treated fruit harvested at 50% skin yellow. f) Irradiated Rainbow and Kapoho fruit had a slower ripening and better quality than non-irradiated fruit after 2 weeks storage at 8-10C. There was much less surface decay on irradiated fruit than on non-irradiated fruit. g) Vapor heated Rainbow and Kapoho fruit had slower ripening and were firmer than non-vapor heated fruit after 2 weeks storage at 8-10C. Surface decay on vapor heated fruit was much less than on non-vapor heated fruit. Papaya transformation is using a inverted repeat inserted into pBI121 vector with two constructs using either the sugarcane ubiquitin or CaMV-35S promoter. We have twenty-eight putative transformed papaya plant with xylanase inserted in the antisense orientation. The mRNA expression patterns are correlated with the pattern of fruit softening during ripening. The xylanase message began to appear in 50% yellow Line 8 fruit and at 75% yellow stage in Sunset. The xylanase was not detected in slow ripening Line 4-16 until the papaya was 4 days after the 100% yellow stage. The most telling data to support this relationship is the expression pattern of the slow ripening line 4-16 where mRNA does not appear until after full skin yellowing has occurred and softening then starts in comparison to the pattern in the commercial lines. The results indicated that the faster a fruit softened the sooner the xylanase gene was expressed. Isozymes proved to be unsuccessful in differentiating rambutan varieties, molecular probes look promising. After screening over 15 molecular probes we have selected six that show varietal variation. Selected molecular probes appear to easily separate the six varieties being used for testing. Rambutan varieties appear to have limited genetic variability.

Impacts
Low acid pineapple hybrids (D-10, CO-2) show less variation in titratable acidity that published for canning varieties. The variety 4-16 is firmer and slowly softened to the eating stage after 21 days of storage. All papaya varieties can be held in storage (8-10C) at the color break stage for up to 2 weeks, longer storage times leads to a significant loss of quality and disease incidence. MCP-treated Rainbow and 4-16 had slower ripening than non-treated fruit. Irradiated Rainbow and Kapoho fruit had a slower ripening and better quality than non-irradiated fruit after 2 weeks storage at 8-10C. Vapor heated Rainbow and Kapoho fruit had slower ripening and were firmer than non-vapor heated fruit after 2 weeks storage at 8-10C. Twenty-eight putative transformed papaya plants with xylanase inserted in the antisense orientation have been generated. The mRNA expression patterns are correlated with the pattern of fruit softening during ripening. The xylanase is expressed began to appear in 50% yellow Line 8 fruit and at 75% yellow stage in Sunset. The xylanase was not detected in slow ripening Line 4-16 until the papaya was 4 days after the 100% yellow stage. The results indicated that the faster a fruit softened the sooner the xylanase gene was expressed. Isozymes proved to be unsuccessful in differentiating rambutan varieties, molecular probes look promising. Six selected molecular probes appear to easily separate the six varieties being used for testing.

Publications

  • Kim, M.S., Moore, P.H., Zee, F., Fitch, M.M.M., Steiger, D.L., Manshardt, R.M., Paull, R.E., Drew, R.A., Sekioka, T. and Ming, R. 2002. Genetic diversity of Carica papaya L. as revealed by AFLP markers. Genome. 45:503-512.
  • Paull, R.E. and Chen, C.C. 2002. Postharvest physiology, handling and storage of pineapple. pp 253-279. In. Pineapple: Botany, Production and Uses. Bartholomew, D. P., Paull, R. E., Rohrbach, K.G., (eds.) CABI, Wallingford, United Kingdom.


Progress 10/01/00 to 09/30/01

Outputs
The vase life of anthurium (Anthurium andraeanum), Heliconia (Heliconia psittacorum cv. `Andromeda', H. chartacea cv. `Sexy Pink'), red and pink ginger inflorescence (Alpinia purpurata) was increased by benzyladenine (BA, 100 mg L-1), applied as a dip or as a spray. Anthurium cultivars that responded positively to BA and were packed for eight days had 20 days longer vase life than non-BA treated flowers. Sucrose began to accumulate rapidly in the non-climacteric pineapple (Ananas comosus L.) fruit 6 weeks before commercial harvest, while in the climacteric papaya (Carica papaya L.) 5 weeks before ripening. Sucrose synthase (SS) activity was high during early papaya and pineapple fruit growth, suggesting involvement in sink strength maintenance, then declined to less than one third within 6 to 8 weeks in papaya and to one fifth in pineapple. The increase in cell wall invertase (CWI) activity coincided with sugar accumulation in papaya fruit. In pineapple, CWI increased 4 weeks before harvest, 2 weeks after sucrose accumulation began to increase. The high CWI activity in papaya and pineapple in the last 4 to 5 weeks of fruit development may assist in fruit sugar accumulation. Availability of genes for SS and CWI may allow modification of fruit growth and final sweetness. Over 1500 ACC antisense putative pineapple transformants exist. Agrobacterium transformation efficiency is still being improved through determination of optimal conditions for source plant material and agro infection conditions. Pineapple fruit translucency begins to appear 2 to 4 weeks before harvest. Flesh tissue became very susceptible to high temperature and the cell electrolyte leakage rapidly increased 4 weeks before harvest. Covering fruit with clear-plastic during the last 3 weeks of fruit development decreased titratable acidity and increased translucency severity. Crown removal either at an early or late stage of fruit development did not have any significant effect on fruit weight or translucency occurrence. The results suggested that the crown did not play a significant role in pineapple fruit development and translucency occurrence.

Impacts
1) Provided the pineapple industry with potential approaches to minimizing fruit translucency that is caused by at least three preharvest factors. Translucency can cause losses of up to 30%. 2) Isolated a biocontrol agent to control postharvest black rot of pineapple. In conjunction with a minimal fungicide dose, this gives control as good as the recommended fungicide dose. The biocontrol agent by itself gives about 80% of the control obtained with commercial fungicide treatment. 3) Developed the use of benzyladenine to extend the postharvest life of tropical flowers and foliage such as anthuriums, ginger and ti leaves. All major anthurium shippers use this treatment on their flowers. 4) Provided the papaya industry with data on the relationship between leaf area and fruit load. This can be used to determine when canopy loss will influence fruit yield and quality. 5) Developed putative transformed pineapple plants to solve the problem of precocious flowering by down regulation of ethylene synthesis. 6) Developed alternative approaches to improving pineapple and papaya fruit sweetness by the modification of sugar metabolism enzymes during fruit growth.

Publications

  • Chen, C.C. and Paull, R.E. 2001. Fruit temperature and crown removal on the occurrence of pineapple fruit translucency. Scientia Horticulturae. 88:85-96.
  • Paull, R.E. and Chantrachit, T. 2001. Benzyladenine and the vase life of tropical ornamentals. Postharvest Biology & Technology. 21:303-310.
  • Zhou, L. and Paull, R.E. 2001. Sucrose metabolism during papaya (Carica papaya) fruit growth and ripening. J. Amer. Soc. Hort. Sci. 126:351-357.
  • Chen, C.C., Zhou, L., Chen, N.J. and Paull, R.E. 2001. Determinants of sweetness in papaya and pineapple. Acta Horticulturae. 553:99-100.


Progress 10/01/99 to 09/30/00

Outputs
Two major postharvest factors appeared to be associated with red ginger senescence: the water balance of the cut stem and the level of stored energy reserves. This conclusion was based on the major symptoms developed during red ginger senescence: inflorescence wilting, and center bract browning. These two senescent symptoms represented more than 90% of the symptoms developed in red ginger during senescence. While the relationship between water balance of the cut stem and vase life of the red ginger has not been established in this study, a positive relationship did exist between sugar content of the cut stem and the flower vase life. Neither ethylene nor the total number of stem microorganisms had an effect on triggering senescence in red ginger. These findings suggested that further improvement of the postharvest handling system for red ginger should concentrate on factors affecting water balance and energy level of the cut stem, rather than those that alter ethylene production or tissue sensitivity, and the number of total microorganisms. A suitable hot water treatment that extending vase life was preconditioning at 40C for 15 min and then treatment at 50C for 12 min, with a 1 h intervening period. However, application of this recommended hot water treatment may induce more damage to the inflorescence bracts in cool season than in summer due to low thermotolerance in cool season. The exposure time in cool season, therefore, should be reduced (i.e. 50C for 10 min), to prevent heat damage. The response of red ginger inflorescence to hot water treatment was dependent on seasonal factors and cultivars. Therefore, the generalized hot water treatment (50C for 12 min) developed for other commodities may not be directly transferable. Hot water treatment could extend the vase life via two major postharvest factors: lowering respiration rate during aging, and maintaining high level of sugar content of the red ginger inflorescences. No relationship was found between the activities of sugar metabolic enzymes (SPS and SS) and content of any sugar after the hot water treatment. Invertase activity was not detected. It was believed that factors other than sugar metabolic enzyme activities per se affected the postharvest sugar content of the red ginger. Other factors could include the respiratory enzyme activities, and changes in stomatal movement. Besides the effects on postharvest physiological factors, hot water treatment had been proven to suppress negative geotropism developed in red ginger inflorescence. The delayed geotropic response can be maintained for up to 7 days.

Impacts
The following recommendation can be made for commercial practices: 1. Inflorescences should be harvest at mature stage (at least 2/3 open stage). 2. After harvest, inflorescences should be washed in tap water containing detergent to remove insect contamination and field heat. 3. Despite seasonal variation in the effecting of hot water treatment (preconditioning at 40 C for 15 min, and then hot water treatment at 50 C for 10 min (winter) to 12 min (summer)) to extend vase life, the treatment should be applied as it suppressed geotropic response during transportation. 4. Inflorescences should be sprayed with 200 ppm of BA before shipping. 5. Inflorescences can be packed wet (moistened newspaper) or dry (dry newspaper), but the plastic liner (20 um thickness) in the cardboard box should not be omitted. 6. After packing, horizontally storage and shipping should not lead to any geotropic curvature for at least 7 days following the heat treatment. 7. The application of chemicals to control ethylene synthesis and action is not effective.

Publications

  • Paull, R.E. 1999. Effects of temperature and relative humidity on fresh commodity quality. Postharvest Biology & Technology. 15:263-277.
  • Hollyer, J., Paull, R. and Huang, A. 2000. Advise on growing and processing of taro for chips. CTAHR - Food Manufacturing #1. 2pp.
  • Chen, C.C. and Paull, R.E. 1999. Quality of Irradiated Cut Flowers. pp. 41-44. In. J.H. Moy and L. Wong (eds) The use of irradiation as a quarantine treatment of food and agricultural commodities. Proc of Workshop, Honolulu, HI., November 10-12, 1997. University of Hawaii, College of Tropical Agriculture and Human Resources 7 Hawaii department of Agriculture.


Progress 10/01/98 to 09/30/99

Outputs
Negative geotropic curvature of fresh asparagus spears after harvest was prevented by a brief heat treatment. The heat treatment was immersion in heated water at 47.5C for 2 to 5 minutes and cooling to storage temperature as soon as possible after heat treatment. The treatment temperature and time needed to be adjusted for spear diameter, small diameter spears required a shorter exposure time or lower temperature. The acridity in Araceae species was not apparently due to the calcium oxalate raphides. The data suggested that a 26 kD protein, possibly a cysteine proteinase, was the active factor. There were a few other uncharacterized protein bands associated with the raphides that could also be involved. Some amino acid sequence data for the 26 kD protein was obtained. The papaya pectin molecular mass declined and the solubility of pectin in cyclohexane-diaminotetraacetic acid and Na2CO3 solutions increased during ripening. The molecular mass decreased and the solubility of hemicellulose in KOH increased during ripening. Water soluble uronic acid increased six-fold during ripening as the yield of cell wall material declined. The pectin fractions were mainly composed of rhamnose, glucose, xylose, galactose, mannose and arabinose, in decreasing order of concentration. Non-cellulosic glucose and xylose were the main neutral sugars in the hemicellulose fraction followed by mannose and galactose and traces of rhamnose and arabinose. These results suggested that pectin hydrolysis and the modification of hemicellulose both were involved in papaya fruit softening. Pectin hydrolysis was apparently more important during the late phase of fruit softening. Pineapple fruit translucency severity was reduced by CaCl2 application. However, the CaCl2 treatment caused slight injury on some crown leaf tips. To improve the efficiency of calcium treatment, a calcium formula is needed that has a high uptake rate by pineapple fruit and without the risk of causing any phytotoxicity. Covering fruit with clear plastic for 1 to 3 weeks at young fruit stage reduced the electrolyte leakage of pineapple fruit flesh cells, suggesting an increase in thermotolerance. During early pineapple fruit development, high day time fruit temperature may increase the fruit heat tolerance, that could reduce the occurrence of heat stress induced fruit translucency during the last stage of fruit development. The total soluble solids, translucency and the activity of cell-wall invertase (CWI) in pineapple fruit flesh were significantly reduced by leaf defoliation. There was a linear cause-effect relationship between the percentage of defoliation and translucency and the CWI activity. A high activity of CWI in pineapple fruit flesh during the last stage of fruit development is a possible cause of pineapple fruit translucency.

Impacts
Negative geotropic curvature of fresh asparagus spears after harvest was prevented by a brief heat treatment. The acridity in Araceae is possibly due to a 26 kD protein, possibly a cysteine proteinase. Papaya pectin hydrolysis was apparently more important during the late phase of fruit softening. A high activity of cell-wall invertase in pineapple fruit flesh during the last stage of fruit development is a possible cause of pineapple fruit translucency.

Publications

  • Paull, R. E. and Chen, N. J. 1999. Heat treatment prevents postharvest geotropic curvature of asparagus spears (Asparagus officinalis L.). Postharvest Biology and Technology. 16:37-41.
  • Paull, R. E., Tang, C.-S., Gross, K. and Uruu, G. 1999. The nature of the taro acridity factor. Postharvest Biology and Technology. 16:71-78.
  • Paull, R. E., Gross, K. and Qiu, Y. 1999. Changes in papaya cell walls during fruit ripening. Postharvest Biology and Technology. 16:79-89.
  • Paull, R. E. 1999. Effects of temperature and relative humidity on fresh commodity quality. Postharvest Biology and Technology. 15:263-277.


Progress 10/01/97 to 09/30/98

Outputs
Immersion of banana (Musa spp. cvs. 'Santa Catarina Prata' and 'Williams') in hot water was evaluated as a potential control procedure for crown rot. Exposure of fruit to water at 55C for 10 min and longer caused severe skin scald and a failure to soften. Scald generally only occurred on fruit treated for 30 min and longer at 50C. Scald development on fruit treated at 45C for 40 min varied with harvest date. When fruit were exposed to hot water at 50C for 20 min, irrespective of the time after dehanding, crown rot was reduced to less than 3%. Hot water treatment has the potential to replace chemical fungicides to control crown rot of banana. Different ranges of temperatures and exposure times were studied to determine suitable hot water treatments to extend red ginger vase life. Hot water at 50C for 12 to 15 min showed a high potential to prolong vase life. Preconditioned flowers lost their tolerance to the hot water treatment if the intervening period between preconditioning and hot water treatment, was longer than 6 hours. The suggested treatment to extend vase life was a reconditioning at 40C for 15 min, standing in the bucket of water at room temperature (22 C) for one hour, and then a hot water treating at 50C for 12 to 15 min. Hot water treatment of litchi at 49C for 20 min proposed as insect disinfestation treatment results in peel damage. When combined with a sulfur dioxide treatment, this damage was prevented with residue in the edible aril on a fresh mass basis of less than 5 mg/kg. Fumigation load factor significantly influenced peel and aril sulfite residues, at 53 kg/m3 aril sulfite residue was 1 mg/kg. The tolerance of `Apple' banana (Musa sp.), avocado (Persea americana Mill.), mango (Mangifera indica L.), papaya (Carica papaya L.), and red ginger (Alpinia purpurata) inflorescences to carbonyl sulfide (COS) fumigation was studied. Avocado tolerated 1% for 7 h and 2% for less than 4 h, while mango tolerated 1% for 3 h and 2% for 1 h and papaya 1% for 16 h. Red ginger inflorescences were less tolerant of COS than fruit, being able to withstand 2% for less than 0.75 h and 1% for less than 2 h. COS may be suitable as a fumigant for surface insects on papaya and avocado.

Impacts
(N/A)

Publications

  • REYES, M.E.Q., NISHIJIMA, W. and PAULL, R.E. 1998. Control of crown rot in `Santa Catarina Prata' and `Williams' banana with hot water treatment. Postharvest Biology and Technology 14:71-75.
  • CHANTRACHIT, T., PAULL, R.E. 1998. Effect of hot water on red ginger (Alpinia purpurata) inflorescence vase life. Postharvest Biology and Technology 14:77-86.
  • PAULL, R.E., REYES, M.E.Q. and REYES, M.U. 1998. Sulfite residues on litchi fruit treated with sulfur dioxide. Postharvest Biology and Technology 14:229-233.
  • CHEN, C.C., PAULL, R.E. 1998. Tolerance of tropical fruits and a flower to carbonyl sulfite fumigation. Postharvest Biology and Technology 14:245-250.
  • NAKASONE, H.Y., PAULL, R.E. 1998. Tropical Fruit. CAB International, England.
  • PAULL, R.E. 1998. Soursop. p386-400. In. P. S. Shaw, H. Chan, S. Nagy (eds.). Tropical and Subtropical Fruits. Agscience, Inc., Auburndale, Florida. 386-400p.
  • PAULL, R.E. 1997. Market access: Disinfestation, unhealthy for insects but safe for people and produce. Proceedings Australiasian Postharvest Horticulture Conference. Hawkesbury, NSW. 39-43p.


Progress 10/01/96 to 09/30/97

Outputs
The proportion of molecular mass range of different extractable fractions of papaya pectin and hemicellulose during fruit ripening was determined. The pectin molecular mass declined and the solubility of pectin in cyclohexane diaminotetraacetic acid and Na2CO3 solutions increased during ripening. The molecular mass decreased and the solubility of hemicellulose in KOH increased during ripening. Water soluble uronic acid increased sixfold during ripening as the yield of cell wall material declined. The loss of high molecular mass pectins decreased throughout ripening while the demethylation rate was greater early in ripening. Changes in pectin molecular size did not parallel loss of fruit firmness during early ripening. These results suggested that pectin hydrolysis and the modification of hemicellulose were involved in papaya fruit softening. Recent development in high pressure food processing of pineapple suggested the possibility of processing a very high quality fresh chilled ready to eat product. There were no significant difference between control and treated pineapple fruit quarter in pH and TSS. High pressures significantly reduced the fruit quarter texture. However, there was no relationship between the reduction in firmness and the degree of pressure applied. The high pressure treatments tested did not consistently produce sterile products. Fruit quarters treated with pressures higher than 400 mPa for 10 min can be stored at 2C for more than one month without microbial spoilage. Holding intact pineapple fruit at 10C before preparing the fruit for pressure treatment alleviated the reduction in yellow color. The tolerance of Brazilian banana (Musa sp.), avocado (Persea americana Mill.), mango (Mangifera indica L.), papaya (Carica papaya L.), and red ginger (Alpinia purpurata (Vieill.) K. Schum) flowers to carbonyl sulfide (COS) fumigation was studied. When the treatment caused severe or extreme skin injury to these fruit, softening was delayed. COS treatments retarded papaya fruit skin coloration and flesh softening, while it promoted avocado softening. Red ginger flowers were less tolerant of COS than fruit, being able to withstand two percent for less than 45 min and one percent for less than 2 hr. The effects of gamma irradiation on vase lives of anthurium cv., dendrobium sprays, Pincushion protea, Bird-of-Paradise, Heliconia psittacorum, red ginger flower and green ti leaf were studied. There were indications of seasonal variation in phytotoxicity and decline in vase life to irradiation. Moderate to severe irradiation damage at 250 Grays to anthurium, dendrobium, heliconia, Bird-of-Paradise, with slight damage to protea makes irradiation procedure unsuitable or marginal for these ornamentals. The new anti-ethylene compound methylcyclopropene (MCP) increases the vase life of dendrobiums about 1.3 fold and oncidium 1.2 fold. More importantly the treatment delays flower drop from the sprays about two fold.

Impacts
(N/A)

Publications

  • Dai, Jingwei and ROBERT E. PAULL. 1997. Comparison of leaf suscepibility to enzymatic blackening in Protea neriifolia R. Br. and Leucospermum 'Rachel'. Postharvest Biology and Technology 11:101-106
  • Zhao, M., J. Moy, and ROBERT E. PAULL, 1996. Effect of gamma-irradiation on ripening papaya pectin. Postharvest Biology and Technology 8:209-222.
  • ROBERT E. PAULL. 1996. Ripening behavior of papaya (Carica papaya L.) Exposed to gamma irradiation. Postharvest Biology and Technology 7:359-370.
  • ROBERT E. PAULL and Wenjun Chen. 1997. Minimal processing of papaya (Caria papaya L) and the physiology of halved fruit. Postharvest Biology and Technology 12:93-99.
  • ROBERT E. PAULL, Wayne Nishijima, Marcelino Reyes and Catherine Cavaletto. 1997. A review of postharvest handling and losses during marketing of papaya (Carica papaya L). Postharvest Biology and Technology 11:165-179.
  • ROBERT E. PAULL and Timothy G. Taylor. 1997. Workshop Proceedings: Enhancing the role of Valued Added Agriculture in Tropical Island Economies. Kona Hawaii, 1996 June 02 to 05. 108pp.
  • ROBERT E. PAULL. 1996. Preparing your fresh and processed products for transport. p84-85. In. J. R. Hollyer, J. L. Sullivan and L. J. Cox (eds.). This Hawaii Product Went to Market. Hawaii Farm Bureau Federation, Honolulu, HI.
  • Nan, G-L., C. Nagai, P. H. Moore, S. S. M. Sun, B. S. Sipes, R. E. PAUll, and K. Rohrbach. 1996. Tissue culture and genetic transformation studies on Pineapple. In Vitro Cell Develop. Biol 32 (3) p 102A.


Progress 10/01/95 to 09/30/96

Outputs
The xylanase gene has been somewhat elusive and a new protein purification run is being made to obtain additional amino acid sequence data. Success in this part of the project could have major impact on our understanding of papaya fruit softening. Cell wall fractions have been sent to USDA - Beltsville for analysis and this is to confirm the role of xylanase in softening. Pineapple translucency begins developing two months before harvest when the tissue shows greater cellular leakage. The development of translucency can be reduced by calcium sprays suggesting some disruption of membrane integrity. The role of crown size in translucency development is still unclear. Benzyladenine, as a spray or dip, can significantly increase the vase life of many anthurium varieties, red and pink flowering ginger, heliconias, and cut leafy materials. There is a seasonal variation in the responsiveness to the spray.

Impacts
(N/A)

Publications

  • PAULL, R. E., and REYES, M. 1996. Preharvest Weather conditions and pineapple translucency. Scientia Horticulturae. 66:59-67.
  • PAULL, R.E. 1996. Ethylene, storage, and ripening temperatures affect Dwarf Brazilian banana finger drop. Postharvest Biology and Technology. 8:65-74.
  • PAULL, R.E. and CHEN, N. 1995. Effect of Heat Treatments on Fruit Ripening and quality. Proc. International Symposium on Postharvest Science and Technology of Horticultural Crops. Beijing, China. June 27-July 01. (Abstract Only).
  • CHEN, N., and PAULL, R.E. 1995. Effect of Waxing and Storage on Pineapple Fruit Quality. Proc. International Symposium on Postharvest Science and Technology of Horticultural Crops. Beijing, China. June 27-July 01. (Abstract Only).
  • PAULL, R.E. 1995. Dwarf Brazilian Banana Finger Drop. Proc 27th Annual Hawaii Banana Industry Association Conference. Kahului, Maui. July 28-29.


Progress 10/01/94 to 09/30/95

Outputs
The papaya fruit ripening xylanase has been purified to two proteins by DEAE, molecular sieve and ion exchange chromatography. Repeated attempts to separate these 32 & 34kD have been unsuccessful. If funds can be secured, both proteins will be sequenced to look for homology. The 32kD protein is the most likely candidate for the xylanase. Work was completed on the use of a sulfur dioxide treatment to limit postharvest browning of litchi and rambutan. The sulfur dioxide residue data is now being analyzed to determine if we meet the international residue tolerance. Pineapple fruit translucency is a major postharvest problem and can lead to significant fruit loss during marketing. A one year study showed a correlation between fruit translucency severity an the temperature three to four months before harvest. In addition, there was a negative correlation between a crown size and translucency severity. This data set has allowed us to develop hypothesis that we are now planning to field test. The injury threshold time and dose rate of the potential fumigant carbonyl sulfide has been determined for papaya, avocado, litchi, banana and red ginger flowers. Initial tests indicate that the products are injured before insect death is achieved. The response of a range of summer grown ornamentals to irradiation has been determined. This test is to be repeated on the same winter grown crops. Irradiation may only have potential use for red gingers and ti leaves.

Impacts
(N/A)

Publications


    Progress 10/01/93 to 09/30/94

    Outputs
    Xylanase was purified from papaya and submitted for polyclonal antibody production. No antibodies to xylanase were detected after a major injection and two boosters. Another large scale purification is underway for antibody production and, if funds are provided, sequencing. A number of sulfur dioxide fumigations with different rates and exposure times were tested on litchi. Samples have been taken and have been forwarded for sulfite analysis. A major study has been initiated to study the effect of insect disinfestation heat treatments on a number of ornamental's vase life. The vase life of a number of ornamentals is increased by heat treatments. Benzyladenine sprays and dips can increase the vase life of some varieties of Anthurium and Heliconia. A disorder of papaya showing low flesh color and sugars is apparently associated with a disruption of the source-sink relationship. Hot water treatment provides some control of crown rot in bananas.

    Impacts
    (N/A)

    Publications


      Progress 10/01/92 to 09/30/93

      Outputs
      Xylanase from ripening papaya has been purified to two proteins. The molecular weight is approximately 34kD. We are now doing large scale purifications to obtain protein to prepare antibodies and additional protein for sequencing. Lizhi and rambutan rapidly loose their external appearance when subjected to insect disinfestation treatments especially hot forced air and hot water. This loss can be controlled by application of sulfur dioxide prior to the insect disinfestation treatment. The sulfur dioxide bleaches the red color that is regrained after disinfestation by a brief acid dip. The time and concentration of sulfur dioxide treatment needs to be correlated with residues on the fruit skin. Protea leaf blackening is due to carbohydrate and water stress. The leaf symptoms expressed differed between the two stresses. The principal stress during packing and shipping is carbohydrate stress associated with carbohydrate withdrawal from the leaves to the flower and nectar secretion. Heliconia postharvest vase life is related to water stress and very poor water uptake. Flowers still attached to the plant take up water in the early morning before dawn when most growth occurs. Poor vascular development compounds the problem of short vase life.

      Impacts
      (N/A)

      Publications


        Progress 10/01/91 to 09/30/92

        Outputs
        Purification of xylanase from ripening papaya is ongoing, considerable problems are being experienced in separating the remaining four proteins. Initial results of carambola, rambutan and litchi to possible insect disinfestations was the focus of this year's research. Carambola appearance loss is serious using forced air treatment with low relative humidity (50%), humidities greater than 90% reduce appearance loss. Some waxes assist in reducing the appearance loss during disinfestation. Rambutan and litchi had considerable appearance loss with no loss of aril quality following all possible physical disinfestation treatments. Waxing fruit before treatment had little effect while wrapped punnetts did help. Sulfur dioxide bleaching retained skin color during heat treatment. Atemoya fruit splitting during ripening was partially reduced by shrink wrapping. Guava can be stored at 15oC for at least 9 days before processing. This storage temperature slowed disease development and still allowed fruit ripening. Lower fruit storage temperatures had higher disease, skin bronzing and some pulp quality loss. Ethylene can be used to ripen mature green guava with no loss of pulp quality. The blackening of protea leaves was shown to be related to severe demand by the flower for nectar production. This demand for carbohydrate was met from the attached leaves. Loss of leaf carbohydrate to the flower lead to a disruption of leaf metabolism and polyphenol oxidase leaf blackening.

        Impacts
        (N/A)

        Publications


          Progress 10/01/90 to 09/30/91

          Outputs
          The papaya fruit ripening research has shown that the disruption of softening following insect heat disinfestation treatments is related to the preharvest temperature regime. The wall degrading enzymes involved in the failure to soften include cellulase, polygalacturonase and xylanase. Work has already been published to show that polygalacturonase is lost after injurious heat treatment. This year we showed that xylanase activity is reduced to 10% in heat injured fruits. This enzyme is now being isolated and purified so that we can produce an antibody probe to determine what step in the synthesis is disrupted by heat. Our purest preparation has four protein bands. Analysis of wall fractions from ripening papaya indicate changes in hemicellulose fractions during ripening that would probably be caused by a xylanase. The variation in postharvest life and failure of Heliconia to respond to most postharvest treatments were studied in detail. The short postharvest life seems to be associated with failure to continue to take up vase solution. This failure does not seem to be related to microbial contamination but to physiological state of the lower flower stem. Cultivar differences are now being studied with the objective of ascertaining the reason for differences.

          Impacts
          (N/A)

          Publications


            Progress 10/01/89 to 09/30/90

            Outputs
            The papaya fruit ripening research has shown that the disruption of softening following insect heat disinfestation treatments is related to the preharvest temperature regime. The temperature in the three days before harvest being most crucial. The response was shown to be due to heatshock protection via physiological and biochemical studies. This protection was shown to last only 24 to 48 hours. The actual component of fruit softening disrupted by heat is unclear and procedures for the isolation of the wall degrading enzymes are nearl finalized. Attention is being paid to the role of xylanase and endo- polygalacturonase in papaya wall softening. These enzymes could be disrupted at either the transcriptional or translational level by heat. The finger "drop" experienced by Dwarf Brazilian banana during ripening is associated with ethylen production. This drop can be nearly completely suppressed by ripening at temperature less than 20oC. Postharvest ethylene treatment also reduce finger "drop" as does storage for two weeks at 15oC.

            Impacts
            (N/A)

            Publications


              Progress 10/01/88 to 09/30/89

              Outputs
              Protea was the major focus of this year's work. Water status was felt to play significant role. This role of water status is clearly modified by the carbohydrate status and possibly the time of harvest in relation to nectar production. Protea neriifolia produce copious quantities of nectar (up to 0.8 ml/day/flower) with 20 to 30% total soluble solids. The sink strength of the flower seems to change during opening placing large demands on the small amount of available carbohydrates in the leaves. Some heliconia postharvest varietal testing was preformed with only limited variability between cultivars. This work is to be repeated. A field trial with five carambola cultivars and three replications were installed at Poamoho. The eight month old trees are flowering and setting fruit. The research on fruiting and development will start in January 1990.

              Impacts
              (N/A)

              Publications


                Progress 10/01/87 to 09/30/88

                Outputs
                The major focus of this year's work has been again on postharvest handling of flowers; dendrobium sprays, proteas and heliconias. The dendrobium spray work has nearly been finished, showing that the use of preservatives is essential, with Florever being the best commercial preservative. Sprays lost postharvest life rapidly if held in the packing box for more than 4 days. Silver compounds are without apparent effect. Water uptake rapidly declines following harvesting. The leaf blackening disorder of protea is related to water loss. There is an interaction between the demand for water by the flower head and leaves. Heliconias have been reluctant in responding to postharvest treatments.

                Impacts
                (N/A)

                Publications


                  Progress 10/01/86 to 09/30/87

                  Outputs
                  The major emphasis of the research this year was on the postharvest handling of dendrobium sprays and protea flowers. A small test was run on Alstroemeria. Dendrobium sprays postharvest life is apparently limited by clogging of the vascular system by bacteria. This clogging leads to reduction in water uptake ability and premature senescence. Silver treatments do not extend postharvest life while the commercial preservative Florever was the best of the products tested. Submerging flowers more than twice postharvest lead to dramatic decline in postharvest life. Protea leaf blackening postharvest is related to water loss. The only treatment to inhibit the development of leaf blackening during shipping was to maintain the product at 1C. The commercial application of this finding is now being pursued. Alstoremeria leaf yellowing can be controlled by a postharvest pulse with gibberllic acid.

                  Impacts
                  (N/A)

                  Publications


                    Progress 10/01/85 to 09/30/86

                    Outputs
                    The work on the preharvest factors (environment and fertilizers) on anthurium postharvest life has been nearly completed. Increasing nitrogen fertilization reduces flower postharvest life unless the level of potassium fertilization is increased as well. Plants which received high nitrogen fertilization had reduced postharvest life and were more likely to wilt and lose gloss. Dendrobium spray postharvest research was expanded following excellent leads obtained in the previous year. There is seasonal variation in postharvest life with late summer flowers having a shorter life. Immediately packing of the flowers is preferable to holding the flowers overnight in winter. The flowers are extremely chilling sensitive with periods as short as one day at temperature less than 10C. The best commercial preservative was Florever giving up to 25% increase in postharvest life. The ginger work was completed, written up and submitted for publication. A major part of the research effort was devoted to papaya. The current postharvest disinfestation treatment in winter leads to a disruption of fruit ripening causing lumps in the flesh. The correlation between preharvest environmental conditions and postharvest sensitivity shows that preharvest minimum and maximum temperatures have a very significant effect. If we can predict the fruit sensitivity to the heat treatment then we have two treatments which will reduce this sensitivity. The heat response found in papaya fruit ripening is of the heat shock type.

                    Impacts
                    (N/A)

                    Publications


                      Progress 01/01/85 to 09/30/85

                      Outputs
                      The work on cut anthurium flowers has been reduced, two papers appeared this year and a third has been accepted. Only one anthurium test is continuing. This test involves a study of the effect of preharvest environment and fertilizer treatments on cut flower life. This test is slated to be finished in March 1986 not December 1985 as mentioned in last year's report. Results from this test will require considerable time to analyze. Work on a pineapple crown preservative showed that this preservative was effective. A commercial company is now seeking EPA and FDA approval for use. The major emphasis this year has been on papaya. The problems experienced by handlers with the hot water disinfestation procedure has led to our consideration of three aspects: (1) can the hard fruit be made to soften following treatment with ethylene, (2) what are the optimum conditions for papaya fruit ripening and (3) can waxes and shrink wraps be used to retain fruit quality? The data is encouraging on the use of both waxes and wraps to reduce water loss, improve appearance and delay ripening. One wax and two shrink wraps have shown considerable promise. The use of ethylene on fruit which has been induced to hard fruitiness has shown that the maturity at the time of hot water treatment is crucial to a response. Work was started on a study of dendrobium postharvest handling. It seems that the commercial Oasis preservative is the best of the commercial preparations. This work will require another year.

                      Impacts
                      (N/A)

                      Publications


                        Progress 01/01/84 to 12/30/84

                        Outputs
                        The work on pineapple waxing has been completed and results accepted for publication. The only work now has been done on pineapple waxing is the comparison of new formulations supplied by commerical firms. Work has been undertaken on a crown preservative with a commerical company. One formulation looks very promising with the company seeking registration for use. A paper on this work for publication will be prepared in the near future. Papaya work with chilling temperatures has been nearly completed, with the last test now being undertaken. A draft manuscript for publication has been prepared waiting for the outcome of this last test. The results look promising and should be useful for growers and shoppers. Anthurium postharvest work is now finished and two papers will appear in press in the near future. One deals with the extension of postharvest life by wax treatment while the second with the senescence process in the flower. A preharvest factor on postharvest life field trial is continuing. This test is due to finish in December 1985 then the results will be fully analyzed.

                        Impacts
                        (N/A)

                        Publications


                          Progress 01/01/83 to 12/30/83

                          Outputs
                          The pineapple waxing work has continued and was compared with controlled atmospheres as a means of reducing postharvest chilling injury. The work has shown that chilling injury is a multistage process with the different stages having differing chilling sensitivities. The initial event in chilling is probably very rapid and probably somewhat reversible. Symptom development is non-reversible, but the system causing the browning reactions are damaged by prolonged chilling stress. Low oxygen atmospheres after removal from chilling stress are effective in decreasing chilling injury symptoms. Papaya can withstand short periods of low temperatures (0 to 10C). The actual boundary between damage is time-temperature dependent and a graph quantitating this response has been developed. Storage relative humidity is an important factor controlling skin scald, an early symptom of chilling injury. Plastic wrapping of fruit reduces skin scald development. Anthurium postharvest life is very dependent upon preharvest environmental conditions and fertilizer application. High nitrogen fertilizer with low doses of potash and phosphorus led to greatly reduced postharvest life. This is a two year test with only one year data to date. Preharvest temperatures is important on postharvest life but the actual correlations have not been computed. Lower temperature preharvest seems to lead to a slightly longer postharvest life.

                          Impacts
                          (N/A)

                          Publications


                            Progress 01/01/82 to 12/30/82

                            Outputs
                            The pineapple fruit waxing studies were completed this year. Fruit waxing significantly help retain fruit appearance and dramatically reduces internal browning symptoms of chilling. This improvement is thought to be due to an effect on internal fruit atmosphere and this is now being pursued via extensive controlled atmosphere studies. Work has started on obtaining background information on changes in pineapple fruit postharvest. Papaya fruit softening during ripening is due to cellulase, polygalacturonase and xylanase activity. Ripening start in the placental area and moves towards the skin. Chilling of fruit at various stages of ripeness produce an aberrant metabolism lead to hard areas near the placenta. The effect of chilling injury at different stages of ripeness is to be studied as a possible method of disinfestation for fruit fly. The changes in soursop fruit during ripening were characterized. Improvement in anthurium flower vase life can be achieved via silver nitrate pulsing; initial studies suggest flower waxing can also add to postharvest life.

                            Impacts
                            (N/A)

                            Publications


                              Progress 01/01/81 to 12/30/81

                              Outputs
                              The work on pineapple waxing to reduce fruit chilling injury symptoms was completed. Waxing significantly reduced severity and incidence of internal browning though shell degreening was inhibited. Low concentrations (50 ppm) ethaphon in the wax, partially alleviates the degreening inhibition. The wall degrading enzymatic levels during fruit ripening were determined. Cellulase activity slowly increased. There was a peak of polygalacturanase and xylanase activity during the early stages at the time of the climacteric rise. These changes are now being correlated with color and deformation force data. Significant improvement in anthurium postharvest life can be achieved by a 30 to 40 minute pulse with 4 mM silver nitrate. Silver thiosulphate was less effective. The findings are being prepared for publication and presentation to the growers.

                              Impacts
                              (N/A)

                              Publications


                                Progress 01/01/80 to 12/30/80

                                Outputs
                                Waxing of pineapple fruit with a polyethylene paraffin mix reduced the symptoms of the chilling disorder; internal browning. This browning occurs within three days after the commodity is removed from the chilling stress (8 degrees C) to nonchilling temperatures (23 degrees C). The effect of waxing is associated with an elevated internal carbon dioxide concentration up to 20%. The extent of this increase in CO(2) is related to the period of stress and "wound" ethylene is also produced in this same period. Silver nitrate can increase the vase life, after simulated shipping of anthuriums, by 50% if done within 24 hours of harvest. Ethylene production which is extremely low is not apparently affected by the silver treatment. Silver treatment does reduce the level of spathe phenol. Protea results prepared for publication.

                                Impacts
                                (N/A)

                                Publications


                                  Progress 01/01/79 to 12/30/79

                                  Outputs
                                  Treatment of papaya fruits with hot water at a temperature of 50 degrees C for 35 minutes was effective for fruit fly control without injuring the fruit. This treatment could possibly be an alternative disinfestation treatment for export papayas. Wax treatment of pineapple caused an increase in carbon dioxide and a slight decrease in oxygen in the fruit atmosphere. The storage life extension and occurrence of endogenous brown spot were not greatly improved by these treatments. Initial work has started on the leaf blackening of Protea exima flower stems which can be partially induced by water stress. Silver nitrate treatments extend the vase life of cut anthurium flowers.

                                  Impacts
                                  (N/A)

                                  Publications


                                    Progress 01/01/78 to 12/30/78

                                    Outputs
                                    In studies to develop alternative disinfestation treatments for export papayas, it seemed that Rotenone (1% commercial preparation) in quantities of 220 to 440 grams in 56.8 liters of hot water (48.9 degrees C for 20 minutes) may be effective for destroying fruit flies without injuring the papayas. It was concluded that hot water dips and high vacuum treatments reported on in the previous report were inappropriate as substitute treatments for ethylene dibromide. The required ethylene dibromide treatment for export bananas hastens ripening. A hot water treatment (48.9 degrees C for 20 minutes) successfully nullified this adverse effect. In commercial shipping of potted Leea plants in refrigerated containers, leaf drop is a major problem. Water deficit in the potting medium and not light or any other factor, was found to be the cause of leaf drop.

                                    Impacts
                                    (N/A)

                                    Publications


                                      Progress 01/01/77 to 12/30/77

                                      Outputs
                                      A heat treatment to hasten the ripening of fresh papayas for processing was developed and recommended to the processing industry. A temperature range of 29.4-32.2 degrees C was found to be optimum for hastening the ripening in the Hilo area where the winter temperatures are 18.3-26.1 Degrees C. Methods to alleviate injury to papayas treated with a possible alternative disinfestation treatment (hot water dip at 46.1 Degrees C for 65 minutes) were investigated, but to no avail thus far. Subjecting papayas to a high vacuum (2-3 mm pressure) for 6 hr seems to kill fruit flies without harming the fruit, thus this treatment may be a successful alternative disinfestation method if ethylene dibromide is disallowed for treating export papayas. Immediately after our test shipment of ornamental plants by surface transportation last year, commercial surface shipments began increasing, and currently three refirgerated containers of ornamental plants are shipped weekly by sea to the U.S. mainland. The only major problem, desiccation of delicate plants in surface transportation, appears to be effectively controlled by adding to the planting media materials such as peat moss or certain commercial preparations that would increase the water retention capacity of the media.

                                      Impacts
                                      (N/A)

                                      Publications


                                        Progress 01/01/76 to 12/30/76

                                        Outputs
                                        Storage decay in papayas from Maui, Kauai, and Oahu (new producing areas) was controlled by the standard hot water treatemnt in laboratory simulated surface shipping tests which also indicated the feasibility of shipping these fruits by sea. Papayas from the Island of Hawaii stored under simulated shipping conditions in a stationary refrigerated commercial shipping container demonstrated the feasibility of surface shipment, provided storage decay was controlled with hot water. Shippers have begun to use sea transportation to take advantage of the lower shipping cost as compared with air shipment. Intensive search for alternative disinfestation treatments for export papayas has revealed the possibility of using phosphine gas or extended low temperature hot water treatment to replace the current ethylene dibromide treatment which faces elimination as a disinfestation method. Methods to alleviate fruit damagecaused by the treatments are being investigated. Growing ornamental foliage plants of 19 species and anthurium flowers shipped for the first time in a commercial refrigerated container from Hawaii arrived in good condition in California and proved the feasibility of shipping them by surface transportation. It is expected that shippers will utilize this method for shipping their ornamentals, especially the large and bulky ones, which cannot beshipped by air, and take advantage of the low shipping cost.

                                        Impacts
                                        (N/A)

                                        Publications


                                          Progress 01/01/75 to 12/30/75

                                          Outputs
                                          Investigations of the physiological basis for the control of endogenous brown spot in refrigerated fresh export pineapples was continued. Refrigeration interferes with the normal patterns of respiration and CyH, production and may cause the appearance of the spots, because fruits heated after refrigeration have higher rates of respiration and CyH, production and lack the spots. To testthis, attempts are being made to increase the rate of these physiological processes by means other than heat, such as CyH, treatment. Experiments on the use of polyethylene packaging and KMnO, (CyH, inactivator) to improve tolerance of avocados to methyl bromide fumigation were initiated. Studies on surface shipment of papayas were reopened, because of the impending possibility of shipping this fruit in refrigerated containers due to accelerating air shipment cost. Fruits from all production areas in Hawaii are being treated with approved disinfestation procedures, stored under simulated shipping conditions, and observed for shelf life. The effect of the standard hot water treatment on decay control and shelf life is being particularly observed. Ornamentals including cut flowers, rooted & unrooted cuttings, & potted plants are included in surface shipment studies. Storage under low Oy, subatmospheres, or COy, controlled premature fading in shipped Vanda orchid flowers. Studies on the control of premature darkening of the leaves of cut flowers of species of Proteawere initiated.

                                          Impacts
                                          (N/A)

                                          Publications


                                            Progress 01/01/74 to 12/30/74

                                            Outputs
                                            In experiments simulating the shipping of anthurium flowers, preshipment treatments with the commercial floral preservatives; Everbloom, Floralife, and Roselife, extended the vase life 1.9, 1.9, and 2.7-fold, respectively; and with:7-Up (acidic, carbonated beverage), benzoic acid, and sodium hypochlorite the vase life was extended 1.4, 1.8, and 1.9-fold, respectively. Currently Hawaiiananthuriums are shipped 1-2 days after harvest. By using preshipment treatments with preservatives, shippers can prevent deterioration of flowers if it becomes necessary to hold them for longer periods before shipping. Factors responsible for the beneficial effects of the preservatives are under investigation. Investigation of the physiological basis for the control of endogenous brown spot in fresh, export pineapples by heat treatment was initiated. Studies on the effect of fruit fly damage on ripening of avocado attached to the tree and respiration and ethylene production of fruit-fly damaged and undamaged fruit were concluded. Damaged fruits began to ripen 10 days earlier on the tree than undamaged, but patterns of respiration and ethylene production were similar for the damaged (abscised) and undamaged (harvested) fruits.

                                            Impacts
                                            (N/A)

                                            Publications


                                              Progress 01/01/73 to 12/30/73

                                              Outputs
                                              Certain commercial floral preservatives and chemicals were effective for vase life extension of anthuriums when applied as a preshipment treatment. Flowers were first held in preservative solutions for several days, then packaged in commercial shipping cartons and held at room temperature for a day or two to simulate air shipping conditions to the U.S. mainland. Then the flowers were removed from the cartons and placed in water to simulate retail conditions. Theuse of these preservatives can now be recommended for vase life extension of export anthuriums. A very effective method for the control of a serious physiological malady, "endogenous brown spot" in fresh export pineapples was developed. The method consists of application of heat (90-100F) for 1 day prior to refrigeration, after refrigeration, or anytime between the start and end of the refrigeration period. That the heat can be applied successfully prior to, during, or after refrigerated transit period was demonstrated in experiments simulating shipping conditions to the U.S. West and East Coasts andJapan. Depending on the severity of the disease, the control is 90-100%.

                                              Impacts
                                              (N/A)

                                              Publications


                                                Progress 01/01/72 to 12/30/72

                                                Outputs
                                                The possibility of extending the vase life of shipped anthurium flowers was demonstrated in flowers held at room temperature for various periods in commercial floral preservations (Floralife, Burpee's Everbloom, Roselife) and then packaged and stored under simulated shipping conditions. Controlled atmosphere storage (4-5% O(2) atmosphere, rest N(2)) also extended the vase lifeat room temperature. When Floralife was used under this controlled atmosphere storage, a further extension of vase life was obtained. Waxing and hypobaric storage also improved vase life of anthuriums in preliminary tests. The proper storage condition in order to prevent the appearance of the physiological malady, "endogenous brown spot" in fresh pineapples seems to be determined by the degree of incidence of the disease at harvest. If the degree of incidence is low, the fruit should be stored at ambient temperatures; if it is high, the fruit should be stored at temperatures slightly above ambient. In either case, excessive accumulation of CO(2) in the storage chamber should be avoided. In any event, fruit should not be refrigerated and then warmed up if the appearanceof the brown spots is to be avoided.

                                                Impacts
                                                (N/A)

                                                Publications


                                                  Progress 01/01/71 to 12/30/71

                                                  Outputs
                                                  Gamma irradiation (50 krad dose) extended shelf life of mature green Haden mangoes by 2 days. This was correlated with delayed attainment of respiratory and ethylene production peaks. If irradiation is approved for treating fresh commodities, it will allow outshipment of Hawaiian mangoes (now prohibited) because the treatment is also effective for disinfestation. A guide for determining proper harvesting stage of papaya was developed for growers: the fruit must be at least 6% yellowed when harvested in order to meet the state minimum grade requirement of 11.5% total soluble solids in the edible pulp. Vascular blockage in the petiole caused by oxidation products limited vase life in anthurium flowers. This was correlated with tannin content of petiole, the variety with less tannin having a longer vase life. Vase life was extended by cutting away portion of petiole with blocked vascular system, by preventing oxidation with the use of anti-oxidants. Optimum pH levels for vase life were below and above 7. Optimum temperature was 55F. Certain chemicals (benzoic acid, N(6) benzyladenine, etc.) and commercial floral preservatives (Floralife, Roselife, etc.) extended vase life through their anti-biotic and anti-oxidative capacities.

                                                  Impacts
                                                  (N/A)

                                                  Publications


                                                    Progress 01/01/70 to 12/30/70

                                                    Outputs
                                                    A continuing program to define optimal disinfestation, shipping and storage of Hawaiian fruits, vegetables and ornamentals yield the following results. IRRADIATION OF LYCHEE - Fresh lychees tolerate only 25 krad dose of gamma irradiation which is sufficient for disinfestation of export fruits, but the shelf life of the fruits is not extended by this treatment. If irradiation as adisinfestation technique for export commodities is approved by the FDA, it can be a substitute for the fumigation procedure used currently. IRRADIATION OF MANGO - Additional data on shelf life extension, respiration, and ethylene production in irradiated mangoes were accumulated, but these must await analysis. PAPAYA SHIPMENT TO JAPAN - Papayas from commercial lots were shipped to Japan under controlled atmosphere or were stored under similar conditions in the laboratory. Shipments were made under 2.8% oxygen (balance nitrogen). The arrival condition and subsequent salability of the actual shipments were checkedagainst the laboratory findings. For better results, 1-1.5% oxygen was recommended to the shippers. ANTHURIUM PRESERVATION - A commercial flower preservative extended the vase life of anthuriums by several days. A significant (p=.01) negative correlation existed between number of salable days and the length and diameter of the petiole and the weight of the whole flower. There was no correlation between salable days and the size of the spathe or spadix. PINEAPPLE STORAGE - "Endogenous brown spot" developed in fresh pineapples when stored at temperatures below 73F. Controlled atmosphere storage (2% oxygen, balance nitrogen) extended the shelf life of pineapples 1-3 days.

                                                    Impacts
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                                                      Progress 01/01/69 to 12/30/69

                                                      Outputs
                                                      The shelf life of hot-water treated, fumigated papayas was extended approximately 1 day by controlled atmosphere storage (oxygen 1 to 1.5% plus nitrogen 99 to 98.5%, at 55F) during a period equivalent of surface shipping from Hawaii to mainland U.S. Hence the feasibility of surface transportation ofHawaiian papaya to mainland markets was demonstrated. The shelf life of fresh pineapples was extended 1 to 3 days by controlled atmosphere storage (oxygen 2% + nitrogen 98%) at 45F. Thus the incorporation of controlled atmosphere into the currently refrigerated storage shipment will result in additional salable days of the pineapples on the retail level on the U.S. mainland. The shelf lifeof hot-water treated papayas was extended 2 to 3 days at 60F by irradiation (75krad of gamma rays). This was correlated with delayed ripening, respiration, and ethylene production. Controlled atmosphere (oxygen 2 to 4 percent + nitrogen 98 to 96 percent) storage of hot-water treated, irradiated papayas further extended the shelf life by about 2 days. Thus the feasibility of the use of irradiation in combination with hot water treatment and controlled atmosphere storage for maximum shelf life maintenance is apparent when irradiation is approved as a disinfestation treatment for Hawaiian papayas for export. These findings have been incorporated into AEC annual reports and in manuscripts prepared for station publication. Much ta were collected on shelf life extension, respiration and ethylene production in irradiated mangoes and lychees, but these must await analyses. Work on shelf life extension of anthuriums and Vanda orchids was also initiated.

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                                                        Progress 01/01/68 to 12/30/68

                                                        Outputs
                                                        Further work on controlling the physiological disease called "internal brown spot" or "black heart" in refrigerated fresh pineapples showed that thus far vacuum treatment applied subsequent to cold storage seems to be the only remedy for this malady. The effect of the application of vacuum treatment prior to cold storage is also being investigated. Respiration and ethylene production were determined for papayas and mangoes harvested at different stages of ripeness and treated with various does of irradiation. The fruits were stored at a ripening temperature of about 77-80F. Daily respiration and ethylene datawill be correlated with chemical data to be obtained on the same fruits by othercooperating departments. Search for fruits suitable for studies on effects of hormones (2,4-D) and ethylene on respiration and ripening indicated that papayas, guavas, passion fruit, and bananas are good working materials. It seems that for these studies measurements of internal carbon dioxide and ethylene are more indicative of the relationships studied than the data on respired carbon dioxide and ethylene.

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                                                          Progress 01/01/67 to 12/30/67

                                                          Outputs
                                                          Preliminary studies indicated the possibility of controlling a serious physiological disturbance called "internal brown spot" which occurs in refrigerated fresh pineapples upon removal to room temperature conditions. Application of vacuum to the fruit subsequent to cold storage decreased the intensity of the physiological malady. Attempts were made to correlate the effect of vacuum treatment with factors such as respiration, ethylene production, fruit weight loss, and pulp translucence. Respiration and ethylene studies on irradiated papayas, mangoes, and avocados were continued. In general, results previously reported were verified in these studies, namely, that the respiratory and ethylene production patterns were altered from the normin accordance with the degree of injury to the fruit by irradiation. Among these fruits, papayas are the most tolerant and avocados the least tolerant to irradiation; mangoes fall between the other two fruits in this respect. Inversely correlated with the degree of tolerance among these fruits is the extent of the alteration in the respiratory and ethylene production patterns. In general, irradiation caused an increase in respiration and ethylene production.

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