Source: UNIVERSITY OF GEORGIA submitted to
SULFUR METABOLISM IN ALLIUM AND BRASSICA
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0188983
Grant No.
(N/A)
Project No.
GEO00947
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Jun 15, 2001
Project End Date
Jun 14, 2006
Grant Year
(N/A)
Project Director
Randle, W. M.
Recipient Organization
UNIVERSITY OF GEORGIA
200 D.W. BROOKS DR
ATHENS,GA 30602-5016
Performing Department
HORTICULTURE
Non Technical Summary
Sulfur flavor compounds are very important to vegetable Allium and Brassica. Genetic as well as environmental factors can affect how sulfur is metabolized and utilized in these important vegetable groups. This project examines how temperature, nitrogen and salinity affect sulfur metabolism in onion. Inbred populations of brassica will be developed and used to study the important metabolic steps in glucosinolate metabolism.
Animal Health Component
50%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
5021451101050%
5021440101050%
Goals / Objectives
Objectives: 1.To study sulfur metabolism into and through the flavor biosynthetic pathway of Allium, with special emphasis on A. cepa. 2.To investigate the bitter and off-flavor compounds in onion and determine those factors which contribute to their increase in concentration. 3.To investigate the effects of growing temperature, nitrogen fertility, and salinity on onion flavor intensity and quality. 4.To develop high and low sulfur accumulating inbred populations of Brassica oleracea for the purpose of: a.Studying the differences in why plants accumulate sulfur to different degrees. b.To determine how plants partition sulfur in the cysteine sulfoxide and glucosinolate pathways when selected for high and low total sulfur accumulation. c.To determine the heritability of sulfur accumulation, methyl cysteine sulfoxide accumulation, and glucosinolate accumulation.
Project Methods
Onion cultivars of different flavor intensity will be greenhouse grown under controlled fertility and temperature regimes. Flavor precursors and precursor intermediates from intact bulb tissues will be analyzed. Total sulfur and sulfate will be measured. Onion cultivars that express high and low bitterness will be evaluated. Flavor precursors and precursor intermediates will be analyzed and associated with any bitter attributes. The lachrymatory factor, only derived from 1 propenyl cysteine sulfoxide will also be analyzed. Juice from bitter and non-bitter varieties will be analyzed by gas chromatography. Unique peaks associated only with bitter onions will be identified by MS GC. Different varieties of short-day onion will be grown at temperatures ranging from 15 to 35 C. First plants will be grown for a specific length of time. Secondly, plants will be grown to maturity at the different temperatures. In a separate group of experiments, plants will be grown in greenhouses with different temperature regimes, harvested at maturity, and analyzed for flavor development. The effect of salinity will be investigated on plants grown in greenhouses. In one group of experiments, different varieties of onion will be grown to maturity with or without the application of sodium chloride. In another experiment, onions will be hydroponically grown with increasing levels of sodium chloride concentrations in the nutrient solutions to determine dose response to sodium chloride and its affect on flavor development. Nitrogen fertility will be studies using hydroponic culture. Plants will be grown to maturity with increasing nitrogen content in the hydroponic solutions. Bulbs will be harvested and subjected to flavor analyses as described above. Rapid cycling populations of Brassica oleracea that were selected during two cycles of simple recurrent selection for high and low selenium accumulation will be selected for high and low total sulfur accumulation. Selected plants in each of the four groups will be self-pollinated for at least eight cycles to develop inbred populations that should differ substantially in sulfur uptake and sulfate accumulation, methyl cysteine sulfoxide accumulation, and glucosinolate accumulation. Inbred populations will be analyzed for sulfur uptake, sulfate accumulation, cysteine sulfoxide accumulation and individual glucosinolate accumulation via HPLC and GC methods. Enzymes involved in sulfur uptake, reduction, and sulfur incorporation into cysteine and methionine will also be assessed. Controlled crosses will be made between high and low accumulating inbreds to obtain genetic populations that can be developed using different mating designs. The genetic populations will be grown and analyzed to determine genetic control of sulfur uptake and metabolism and their heritabilities.

Progress 06/15/01 to 06/14/06

Outputs
During the course of this project, factors were tested using the scientific methods to determine their effects on sulfur uptake and metabolism and the subsequent effect on sulfur secondary metabolites that impact flavor or flavor development. Factors such as temperataure, nitrogen availability, sodium and calcium cholride, zinc, irrigation and storage duration all affect sulfur metabolism in Allium and Brassica, and subsequently the flavor and flavor development.

Impacts
As factors influencing sulfur uptake and metabolism are better understood, the production of Brassica and Allium crops can be grown with the expressed intent of providing specific flavors or flavor experiences when consumed. Farmers, producers, or processors can utilize these research results to make better decisions regarding practices or methods used to modify Allium and Brassica flavor.

Publications

  • Lefsrud, M.G., D.A. Kopsell, D.E. Kopsell, and W.M. Randle. 2006. Kale carotenoids are unaffected while biomass production, elemental concentration and selenium accumulation respond to changes in selenium fertility. J. Ag. Food Chem. 54:1764-1771. Coolong, T.W. and W.M. Randle. 2006. The influence of root zone temperature on growth and flavor precursors in Allium cepa L. J. Hort. Sci. Biotech. 81:199-204.
  • Chang, P. and W.M. Randle. 2005. Sodium chloride timing and length of exposure affect onion growth and flavor. J. Plant Nutrition. 28: 1755-1766.
  • Chang, P. and W.M. Randle. 2006. Influence of temperature on selenium and sulfur accumulation in Brassica oleracea. J. Hort. Sci. Biotech. Accepted 2006.
  • Boyhan, G.E., A.C. Purvis, W.M. Randle, R.L. Torrance, M.J. Cook, G. Hardison, R.H. Blackley, H. Paradice, C.R. Hill, and T. Paulk. 2005. Harvest and postharvest quality of short-day onions in variety trials in Georgia, 2000-1003. Hort Tech. 15: 694-706.
  • Randle, W.M. 2004. Chloride requirements in onion: Clarifying a widespread misunderstanding. Better Crops Plant Food. 88: 10-11.
  • Diaz-Perez, J.C., W.M. Randle, G. Boyhan, R.W. Walcott, D. Giddings, D. Bertrand, H.F. Sanders, and R.D. Gitaitis. 2004. Effects of mulch and irrigation system on sweet onion: I. Bolting, plant growth, and bulb yield and quality. J. Amer. Soc. Hort. Sci. 129: 218-224.
  • Chang, P. and W.M. Randle. 2004. NaCl in nutrient solutions can affect onion growth and flavor development. HortScience. 39: 1421-1425.
  • Coolong, T.W., H.D. Toler, C.E. Sams, and W.M. Randle. 2004. Zinc availability in hydroponic culture influences glucosinolate concentrations in Brassica rapa L. HortScience. 39: 84-86. Coolong, T.W., D.A. Kopsell, D.E. Kopsell, and W.M. Randle. 2004. Nitrogen and sulfur influence nutrient usage and accumulation in onion (Allium Cepa L.). J. Plant Nutr. 27: 1813-1826.
  • Coolong, T.W. and W.M. Randle. 2003. Sulfur and nitrogen availability interact to affect the flavor biosynthetic pathway in onion. J. Am. Soc. Hort. Sci. 128:776-783.
  • Kopsell, D.E., D.A. Kopsell, T.W. Coolong, W.M. Randle, C.A. Sams, J. Curran-Celentano. 2003. Kale Carotenoids Remain Stable while Flavor Compounds Respond to Changes in Sulfur Fertility. J. Agric. Food Chem. 51:
  • Coolong, T.W. and W.M. Randle. 2003. Ammonium nitrate fertility levels influence flavour development in hydroponically grown Granex 33 onion. J. Sci. Food Agric. 83: 477-482. Coolong, T.W. and W.M. Randle. 2003. Zinc concentration in hydroponic solution culture influences zinc and sulfur accumulation in Brassica rapa L. J. Plant Nutr. 26: 949-959.
  • Kopsell, D.A., D.E. Kopsell, and W.M. Randle. 2003. Seed germination response of rapid-cycling Brassica oleracea grown under increasing sodium selenate. J. Plant Nutrition 26: 1355-1366.
  • Coolong, T.W. and W.M. Randle. 2003. Temperature influences flavor intensity and quality in Granex 33 onion. J. Am. Soc. Hort. Sci. 128: 176-181.
  • Randle, W.M., D.E. Kopsell and D.A. Kopsell. 2002. Sequentially reducing sulfate fertility during onion growth and development affect bulb flavor at harvest. HortScience. 37:118-121.
  • Kopsell, D.E., W.M. Randle and N.E. Schmidt. 2002. Incubation time, cultivar, and storage duration affect onion lachrymatory factor quantification. HortScience. 37:567-570.
  • Charron, C.S., D.A. Kopsell, W.M. Randle, and C.E. Sams. 2001. Sodium selenate fertilization increases selenium accumulation and decreases glucosinolate concentration in rapid-cycling Brassica oleracea. J. Sci. Food and Agric. 81:962-966.
  • Randle, W.M. 2001. Opportunities and strategies for manipulating onion flavour. Acta Hort. 555: 57-61.
  • Kopsell, D.A., W.M. Randle, M.A. Eiteman. 2001. Changes in S-alk(en)yl cysteine sulfoxides and precursor intermediates during storage among short and long day onion cultivars. Acta Hort. 555:153-156.
  • Kopsell, D.E. and W.M. Randle. 2001. Genetic variances and selection potential for selenium accumulation in a rapid-cycling Brassica oleracea population. J. Am. Soc. Hort. Sci. 126:329-335.


Progress 01/01/04 to 12/31/04

Outputs
Progress continues in furthering our understanding of those factors that influence sulfur uptake and metabolism in plants leading to the accumulation of flavor and therapeutic compounds of a secondary metabolic nature. Through several experiments, we demonstrated that sodium chloride did not really affect pungency in onion until salt levels became so high that plant growth was severerly affected. This has implications in that onions are produced on sodic soils and demonstrates the fact that the flavor system is not affected, only growth. Work with zinc uptake and accumulation in Brassica revealed two interesting things. One, was that zinc does affect sulfur uptake and accumulation with higher zinc fertility lowering the amount of sulfur that is absorbed by Brassica plants. The second interesting response to high zinc fertility levels was that if made available, plants will absorb very high levels of zinc, even after growth has apparently stopped.

Impacts
By continuing to understand those factors that influence sulfur uptake and metabolism, we can better control the consistency of vegetable flavors and avoid situations where flavor become objectionable.

Publications

  • Diaz-Perez, J.C., W.M. Randle, G. Boyhan, R.W. Walcott, D. Giddings, D. Bertrand, H.F. Sanders, and R.D. Gitaitis. 2004. Effects of mulch and irrigation system on sweet onion: I. Bolting, plant growth, and bulb yield and quality. J. Amer. Soc. Hort. Sci. 129: 218-224.
  • Chang, P. and W.M. Randle. 2004. NaCl in nutrient solutions can affect onion growth and flavor development. HortScience. 39: 1421-1425.
  • Coolong, T.W., H.D. Toler, C.E. Sams, and W.M. Randle. 2004. Zinc availability in hydroponic culture influences glucosinolate concentrations in Brassica rapa L. HortScience. 39: 84-86. Coolong, T.W., D.A. Kopsell, D.E. Kopsell, and W.M. Randle. 2004. Nitrogen and sulfur influence nutrient usage and accumulation in onion (Allium Cepa L.). J. Plant Nutr. 27: 1813-1826.


Progress 01/01/03 to 12/31/03

Outputs
Factors influencing onion flavor development and Brassica sulfur uptake and metabolic activity were investigated. Zinc was shown to affect glucosinolate and cysteine sulfoxide content in Brassica napa. NaCl affect onion growth and flavor intensity and composition in onion. Nitrogen and sulfur interacted to affect onion flavor. Onion were being developed with lower flavor intensity.

Impacts
Information generated from these studies will influence on ecomonically important vegetable will be grown for improved palatability and improved nutritional value.

Publications

  • Coolong, T.W. and W.M. Randle. 2003. Sulfur and nitrogen availability interact to affect the flavor biosynthetic pathway in onion. J. Am. Soc. Hort. Sci. 128:776-783.
  • Kopsell, D.E., D.A. Kopsell, T.W. Coolong, W.M. Randle, C.A. Sams, J. Curran-Celentano. 2003. Kale Carotenoids Remain Stable while Flavor Compounds Respond to Changes in Sulfur Fertility. J. Agric. Food Chem. 51:
  • Coolong, T.W. and W.M. Randle. 2003. Ammonium nitrate fertility levels influence flavour development in hydroponically grown `Granex 33' onion. J. Sci. Food Agric. 83: 477-482.
  • Coolong, T.W. and W.M. Randle. 2003. Zinc concentration in hydroponic solution culture influences zinc and sulfur accumulation in Brassica rapa L. J. Plant Nutr. 26: 949-959.
  • Kopsell, D.A., D.E. Kopsell, and W.M. Randle. 2003. Seed germination response of rapid-cycling Brassica oleracea grown under increasing sodium selenate. J. Plant Nutrition 26: 1355-1366.
  • Coolong, T.W. and W.M. Randle. 2003. Temperature influences flavor intensity and quality in 'Granex 33' onion. J. Am. Soc. Hort. Sci. 128: 176-181.


Progress 01/01/02 to 12/31/02

Outputs
Several experiments were conducted to determine the effects of temperature on onion flavor. Temperature was shown to increase bulb flavor intensity at two stages of development as temperature increased from 12 to 30 degress C. In two experiments, hydroponically grown onions were subjected to various levels of salinity and evaluated for growth and flavor changes. In both cases, growth was severely restricted as exposure to salinity increased, while flavor was only affected at excessive salinity levels. Nitrogen was evaluated to determine its affect on flavor intensity and quality in onion. Over a broad range of nitrogen treatments, methyl cysteine sulfoxide was greately affected by the level of nitrogen provided.

Impacts
Understanding how environmental factors, such as temperature, nitrogen avaliability, and salinity, affect onion flavor quality and intensity will provide information to growers so they can make better decisions in growing onions of better quality.

Publications

  • Randle, W.M., D.E. Kopsell and D.A. Kopsell. 2002. Sequentially reducing sulfate fertility during onion growth and development affect bulb flavor at harvest. HortScience. 37:118-121.
  • Kopsell, D.E., W.M. Randle and N.E. Schmidt. 2002. Incubation time, cultivar, and storage duration affect onion lachrymatory factor quantification. HortScience. 37:567-570.
  • Boyhan, G.E., A.C. Purvis, W.M. Randle, P.M. Lewis, J.T. Paulk, R.L. Torrance, D.E. Curry, M. Linton. 2002. Vidalia onion variety trials 2001-2002. Onion Research Ext. Rep. No.3, 1-10.
  • Chang, P. and W.M. Randle. 2002. The effects of different NaCl concentrations on salad onion flavor. Onion Res.-Ext. Rep 2001. No. 3:13-16.
  • Coolong, T.W. and W.M. Randle. 2002. The effects of temperature during the growing season upon the flavor of onions. Onion Res.-Ext. Rep. 2001.No. 3: 17-19.