Source: UNIVERSITY OF CALIFORNIA, DAVIS submitted to
GENETIC IMPROVEMENT OF WALNUT
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0168984
Grant No.
(N/A)
Project No.
CA-D*-PLS-5975-H
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Oct 1, 2004
Project End Date
Jun 30, 2009
Grant Year
(N/A)
Project Director
McGranahan, G. H.
Recipient Organization
UNIVERSITY OF CALIFORNIA, DAVIS
410 MRAK HALL
DAVIS,CA 95616-8671
Performing Department
PLANT SCIENCES
Non Technical Summary
The walnut industry is faced with substantial losses due to pests and diseases affecting both cultivars and rootstocks. In addition the crop is becoming genetically vulnerable due to extensive planting of one cultivar. This project will produce new cultivars and rootstocks to alleviate the problems faced by the walnut industry
Animal Health Component
40%
Research Effort Categories
Basic
20%
Applied
40%
Developmental
40%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2011213108060%
2021213108020%
2051213108010%
2121213108010%
Goals / Objectives
The objectives of the Walnut Improvement Program are to breed and engineer new walnut cultivars and rootstocks that serve a need in the California walnut industry and to develop the germplasm, knowledge and tools for future genetic improvement. Traits targeted for improvement for new cultivars include hypersensitivity to the cherry leaf roll virus (CLRV), blight resistance, increased precocity and earlier harvest dates. For rootstock the objective is to develop clonal rootstock and the means to produce it. Traits of interest include resistance to Phytophthora root and crown rots, crown gall, nematodes and tolerance to the cherry leafroll virus.
Project Methods
This is a long-term project that involves on-going research in 1) marker-assisted backcross breeding to introduce the hypersensitive response to CLRV found in black walnut into a commercially acceptable cultivar of English walnut; 2) conventional breeding, evaluation, selection and field trials to develop new high quality, early-harvesting cultivars; 3) micropropagation, embryo rescue, and somatic embryogenesis to develop and propagate new rootstocks and 4) gene transfer, plant regeneration and field testing to produce and evaluate transgenic trees.

Progress 10/01/04 to 06/30/09

Outputs
OUTPUTS: The goal of the Walnut Improvement Program is to provide the United States walnut industry with new rootstocks and cultivars that solve some of their most pressing problems. During this project 6 new cultivars and rootstocks have been patented or have the patent submitted and pending. These include Ivanhoe, an early harvesting cultivar and the most recently released; Sexton, a mid-season cultivar with abundant yield; Gillet, a mid-season cultivar that shows some resistance to blight and Forde, a late season cultivar with superior nut quality. Two new clonal rootstocks include VX211 with tolerance to nematodes and RX1 with some resistance to Phytophthora root and crown rot. The performance and background of these cultivars has been presented nationally and internationally. In addition techniques for micropropagation and acclimatization have been improved and shared with labs that are intent on commercially propagating the newly released rootstocks. PARTICIPANTS: Charles Leslie, Staff Research Associate Greg Browne, USDA-ARS Dan Kluepfel, USDA-ARS Michael McKenry, UC Riverside TARGET AUDIENCES: The target audiences include farm advisors, growers and processors involved in walnut production through the annual walnut research conference and county meetings, as well as national and international scientists. I gave a keynote speech at the International Society for Horticultural Science in 2009 and have been chair of the walnut working group of ISHS for 6years. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The impact of these cultivars will be substantial. Perhaps most important is the cultivar Ivanhoe that was released and disseminated to growers this year. The demand for wood of this cultivar has been great because the most commonly planted cultivar Chandler is very late harvesting. One of the activities of the Walnut Improvement Program that has served us and the industry well is the annual crackout meeting. Any grower or nursery can attend who has an intense interest or enthusiasm for breeding walnuts. The day-long meeting includes individually reviewing data and evaluating the nuts which are on display, usually from about 300 seedlings and selections, followed by a group discussion. Their input is invaluable.

Publications

  • McGranahan, Gale and Joe Grant. Walnuts. 2008. Juglans pp 425-437 In: J .Janick (ed). Encyclopedia of Fruits and Nuts. CABI Oxfordshire UK
  • Britton, M., Leslie, C., McGranahan, G. and Dandekar, A. 2007. Juglans, Walnuts. pp 349-370. In: Pua, E.C. and Davey, M.R. (eds.) Transgenic Crops V. Biotechnology in Agriculture and Forestry. Springer. Heidelberg, Germany.
  • McGranahan, G. 2007. Molecular genetics of walnuts, a breeders perspective. Acta Hort 738:111-115.
  • Ibrahimov, ZA, McGranahan, GH, Leslie, CA, Aradhya, MK. 2007 Persian walnut improvement in Azerbaijan. Annals of Agrarian science. 5:18-21
  • Britton, M., Leslie, C., Caboni, E., Dandekar, A, and McGranahan, G. 2008 Persian Walnuts. pp 285-300. In: Kole, C. and Hall, T.C. (eds.) A Compendium of Transgenic Crop Plants: Transgenic Temperate Fruits and Nuts. Blackwell Publishing, Oxford. UK.
  • Leslie, C.A. and G. H. McGranahan. 2009. Walnut micropropagation, rooting, and acclimatization. In: Adventitious Root Formation in Forest Trees and Woody Horticultural Crops, From Genes to Applications. Research Signpost Pub. Kerala, India
  • Luedeling, E., MH Zheng, Chuck Leslie and Gale McGranahan., 2009 Validation of winter chill models using historic records of walnut phenology. Agric.Forest Meteorol. 4115:1-11


Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: The goal of the Walnut Improvement Program is to breed or engineer new walnut cultivars and rootstocks that serve a need in the walnut industry and to develop germplasm, knowledge and tools for future breeding efforts. Traits targeted for cultivar improvement include pest and disease resistance, increased precocity and earlier harvest dates. Several early harvesting genotypes have been selected and established in field trials. We have also identified an early harvesting selection (95-11-14) that we plan to submit for patenting next year. Work has continued in selection, micropropagation and field testing of clonal Paradox rootstocks. The goal is to develop walnut rootstocks with resistance or tolerance to Phytophthora, nematodes, crown gall, and blackline disease. One large replicated field trial of the most promising clones was established this year in San Joaquin County and materials were propagated for another well designed trial in Yolo County to be planted in spring 2009. Two rootstocks (VX211 and RX1) have been submitted for patenting and three private labs/nurseries are propagating them commercially. PARTICIPANTS: This is a multidisciplinary project with many collaborators. From Farm Advisors (University of California Cooperative Extension) who trial new selections and varieties to nematologist (Michael McKenry, University of California, Riverside), and Plant Pathologists (Dan Kluepfel and Greg Browne, USDA/ARS) who do extensive disease screening. I also have numerous University of California, Davis undergraduates working in my lab and field sites and a graduate student working in the lab. My Staff Research Associate, Charles Leslie is also invaluable. TARGET AUDIENCES: The target audiences range from American consumers of this healthy nut, California growers (walnuts are only grown in California) and processors and handlers, and the export market. Scientists, especially those involved in genetic improvement also benefit from the work done in this project. Results of this project are presented annually in numerous county meetings, field days, the Walnut Research Conference and frequently in other national and international venues. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Micropropagation of walnuts has been commercialized due to the potential of our new released rootstocks. Several of our methods of propagation have been adopted by commercial labs and nurseries. As a result of the Walnut Breeding Program walnut growers continue to plant extensively the cultivars Tulare, Chandler and Howard. There is also demand for the three new cultivars.

Publications

  • Britton, M., Leslie, C., Caboni, E., Dandekar, A, and McGranahan, G. 2008. Persian Walnut. In: Kole, C. and Hall, T.C. (eds.) Compendium of Transgenic Crop Plants: Transgenic Temperate Fruit and Nut Crops. Blackwell Publishing, Oxford UK pp285-300.
  • McGranahan, G. and C. Leslie 2008. Breeding walnuts (Juglans regia). In: S.M. Jain and P.M. Priyadarshan (eds.) Breeding Plantation Tree Crops. Springer, NY pp 249-273.
  • McGranahan, Gale and Joe Grant. Walnuts. 2008. Juglans In: J .Janick (ed). Encyclopedia of Fruits and Nuts. CABI Oxfordshire UK pp 425-437
  • McGranahan, G. 2007. Molecular genetics of walnuts - a breeder's perspective. Acta Hort 738:111-115.


Progress 01/01/07 to 12/31/07

Outputs
The goal of the Walnut Improvement Program is to breed or engineer new walnut cultivars and rootstocks that serve a need in the walnut industry and to develop germplasm, knowledge and tools for future breeding efforts. Traits targeted for cultivar improvement include pest and disease resistance, increased precocity and earlier harvest dates. Several early harvesting genotypes have been selected and established in field trials. Work has continued in selection, micropropagation and field testing of clonal Paradox rootstocks. The goal is to develop walnut rootstocks with resistance or tolerance to Phytophthora, nematodes, crown gall, and blackline disease. Over 5000 rootstocks have been grown in the nursery, over 3000 of these have been grafted to Chandler and will be ready for field trials in 2008. Two rootstocks (VX211 and RX1) have been submitted for patenting and three private labs/nurseries are propagating them commercially.

Impacts
Micropropagation of walnuts has been commercialized due to the potential of our new released rootstocks. Several of our methods of propagation have been adopted by commercial labs and nurseries. As a result of the Walnut Breeding Program walnut growers continue to plant extensively the cultivars Tulare, Chandler and Howard. There is also demand for the three new cultivars.

Publications

  • Britton M.T., Leslie C.A., McGranahan G.H. and Dandekar A.M. 2007. Walnut. In: Transgenic Crops V. Ed: E.C. Pua and M.R. Davey. Pub in Biotechnology in Agriculture and Forestry Vol. 60. Springer, Heidelberg, Germany. pp. 349-370.


Progress 01/01/06 to 12/31/06

Outputs
The goal of the Walnut Improvement Program is to breed or engineer new walnut cultivars and rootstocks that serve a need in the walnut industry and to develop germplasm, knowledge and tools for future breeding efforts. Traits targeted for cultivar improvement include pest and disease resistance, increased precocity and earlier harvest dates. Three new cultivars were patented and released: Forde, Sexton and Gillet. These come into bearing young with high yields of jumbo-sized walnuts that can be processed inshell or cracked. They bear fruit laterally and yield a crop that can be harvested midseason. All three exhibit low susceptibility to blight and are suitable to a range of growing conditions in California. Grafting wood has been distributed and 12 nurseries have been licensed. Two long term field trials have been established. Materials now under evaluation include 17 thousand full and half sib crosses. Controlled crosses this year only yielded about 200 seedlings. Work has continued in selection, micropropagation and field testing of clonal Paradox rootstocks. The goal is to develop walnut rootstocks with resistance or tolerance to Phytophthora, nematodes, crown gall, and blackline disease. Almost 4000 rootstocks have been grown in the nursery, over 3000 of these have been grafted to Chandler and will be ready for field trials in 2007 and 2008. Three rootstock clones have been genetically modified for crown gall resistance via RNAi with 40 different insertion events. In vitro assays and preliminary screening indicate that most of the clones are highly resistant to crown gall.

Impacts
Micropropagtion of walnuts has been commercialized due to the potential of our new selected rootstocks. Several of our methods of propagation have been adopted by commercial labs and nurseries. As a result of the Walnut Breeding Program walnut growers continue to plant extensively the cultivars Tulare, Chandler and Howard. There is also significant demand for the three new cultivars.

Publications

  • McGranahan, G.. and Leslie, C. 2006. Walnut tree named Sexton. US Patent No. 16,496
  • McGranahan, G.. and Leslie, C. 2006. Walnut tree named Gillet. US Patent No. 17,135
  • McGranahan, G.. and Leslie, C. 2006. Walnut tree named Forde. US Patent No. 16,495


Progress 01/01/05 to 12/31/05

Outputs
The goal of the Walnut Improvement Program is to breed or engineer new walnut cultivars and rootstocks that serve a need in the walnut industry and to develop germplasm, knowledge and tools for future breeding efforts. Traits targeted for improvement include pest and disease resistance, increased precocity and earlier harvest dates. Materials now under investigation include over 18 thousand full and half sib seedlings. Over 50 selections have been made from among the mature progeny. Three have been submitted for patenting. These are Sexton, Gillet and Forde characterized by an earlier harvest date than Chandler and large, light kernels. Sexton is protandrous and Forde and Gillet are protogynous. Seven field trials of selected rootstock clones were established. Two clones appear promising when challenged with Phytophthora cinnamomi in the field. Over 1200 of our micropropagated rootstocks were grown in the nursery row and over 2000 are ready for nursery planting or pest and disease testing now.

Impacts
As a result of this program walnut growers are extensively planting the new cultivar "Tulare", a vigorous and precocious cultivar with high yields and quality. Tulare has also been identified as a unique source of resistance to aflatoxin. There is also significant demand for the three recently released cultivars: Sexton, Gillet and Forde. We have also been working with a California nursery to commercialize micropropagation techniques for clonal rootstock release.

Publications

  • Dangl G., Woeste K., Aradhya M., Koehmstedt A., Simon C., Potter D., Leslie C. and McGranahan G. 2005. Characterization of 14 microsatellite markers for genetic analysis and cultivar identification of walnut. J. Amer. Soc. Hort. Sci. 130:348-354.
  • Dandekar A., Leslie C., and McGranahan G. 2005. Juglans regia walnut. pp 307-323 In: R.E. Litz (ed.) Biotechnology of Fruit and Nut Crops. CABI Publishing. Oxfordshire UK.
  • Grant, J., and McGranahan G.. 2005. English walnut rootstocks help avoid blackline disease, but produce less than 'Paradox' hybrid. California Agriculture:249-252.


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

Outputs
The goal of the Walnut Improvement Program is to breed or engineer new walnut cultivars and rootstocks that serve a need in the walnut industry and to develop germplasm, knowledge and tools for future breeding efforts. Traits targeted for improvement include pest and disease resistance, increased precocity and earlier harvest dates. Materials now under investigation include 8,300 seedlings derived from controlled crosses or supplemental pollen crosses. Over 5o selections have been made from among the progeny of previous crossings. Three have been submitted for patenting. These are Sexton, Gillet and Forde characterized by an earlier harvest date than Chandler and large, light kernels. Sexton is protandrous and Forde and Gillet are protogynous. Over 1500 selected rootstocks from 17 different clones have been micropropagated and nursery grown for field trials. An additional 1163 have been grown for retesting against nematodes, crown gall or Phytophthora. The SCAR markers designed to aid in selection of progeny with hypersensitivity to the cherry leaf roll virus in backcross populations have been improved with very clear differentiation of bands visible in agarose gels.

Impacts
As a result of this program walnut growers are extensively planting the new cultivar 'Tulare', a vigorous and precocious cultivar with high yields and quality. Tulare has also been identified as a unique source of resistance to aflatoxin. There is also significant demand for the three recently released cultivars: Sexton, Gillet and Forde.

Publications

  • Vahdati, Kourosh, Charles A. Leslie, Zabihollah Zamani and Gale H. McGranahan. 2004. Rooting and acclimatization of in-vitro grown shoots from mature trees of three Persian walnut cultivars. HortScience 39:324-327.
  • McGranahan, Gale and Chuck Leslie. 2004. 'Robert Livermore', a Persian walnut with a red seedcoat. HortScience 39:1772.
  • Comstock, S.S., G. McGranahan, W.R. Peterson and S.S. Teuber. 2004. Extensive in vitro cross-reactivity to seed storage proteins is present among walnut (Juglans) cultivars and species. Clin. Exp. Allergy 34:1583-1590.


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

Outputs
The goal of the Walnut Improvement Program is to breed or engineer new walnut cultivars and rootstocks that serve a need in the walnut industry and to develop germplasm, knowledge and tools for future breeding efforts. Traits targeted for improvement include pest and disease resistance, increased precocity and earlier harvest dates. Materials now under investigation include 7,000 seedlings derived from controlled crosses or supplemental pollen crosses. Over 50 selections have been made from among the progeny of previous crossings. Four of these have advanced as releases for patenting. Over 20 rootstock selections have been micropropagated for field trials and confirmation testing. The SCAR markers designed to aid in selection of progeny with hypersensitivity to the cherry leaf roll virus in backcross populations have been improved with very clear differentiation of bands visible in agarose gels.

Impacts
As a result of this program walnut growers are extensively planting the new cultivar 'Tulare', a vigorous and precocious cultivar with high yields and quality. 'Tulare' has also been identified as a unique source of resistance to aflatoxin.

Publications

  • McGranahan, G., Leslie, C. and Phillips, H.A. 2001. Persian walnut tree named 'Robert Livermore'. United States Plant Patent 12,264 P2. Date of Patent: Dec. 11, 2001.
  • Escobar, M.A., Leslie, C.A., McGranahan, G.H. and Dandekar, A.M. 2002. Silencing crown gall disease in walnut (Juglans regia L.). Plant Science 163:591-597.
  • Mahoney, N., Molyneux, R.J., McKenna, J., Leslie, C.A. and McGranahan, G. 2003. Resistance of 'Tulare' walnut (Juglans regia cv. Tulare) to aflatoxigenesis. Journal of Food Science 68(2):619-622.


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

Outputs
Our goal is to provide the California walnut industry with superior varieties through breeding and genetic engineering. It is proceeding swiftly due to the enthusiasm of participants at our annual crack-out meeting and the first Walnut Breeding Day. In the field we evaluated almost 2000 trees and cracked out nut samples from over 1300. We have 10 grower field trials underway and several more planned. A total of 54 selections have been identified at the planned meeting in March. Many of these are targeted for general areas of the state, for example early harvest regardless of leafing date for the South and low blight for the North. In the coming year we expect to begin testing quality selections in growers orchards for resistance to blackline for the central area. Cross-pollinations this year generated in excess of 8,000 seed. Laboratory work including improvements in micropropagation, was highly successful. The media and conditions for the accumulation phase of rooting were optimized and the plants were produced for disease resistance testing. We also cooperated in the crown gall research of Dandekar and Escobar and aflatoxin research with USDA.

Impacts
New walnut cultivars have had a major impact on walnut production in the US. The majority of trees now planted are derived from UC breeding programs.

Publications

  • Potter, Daniel, Fangyou Gao, Giovanna Aiello, Charles Leslie, and Gale McGranahan. 2002. Intersimple sequence repeat markers for fingerprinting and determmining genetic relationships of walnut (Juglans regia) cultivars. J.Amer. Soc. Hort Sci. 127(1):75-81.
  • Potter, Daniel, Fangyou Gao, Scott Baggett, James R. McKenna, and Gale H. McGranahan. 2002. Defining the sources of Paradox: DNA sequence markers for North America walnut (Juglans L.) species and hybrids. Scientia Horticulturae 94:157-170.
  • Vahdati, Kourosh, James R. McKenna, Abhaya M. Dandekar, Charles A. Leslie, Sandie L. Uratus, Wesley P. Hackett, Paola Negri, and Gale H. McGranahan. 2002. Rooting and other characteristics of a transgenic walnut hybrid ( Juglans hindsii x J.regia)rootstock expressing rolABC. J Amer. Soc. Hort. Sci. 127(5):724-728.
  • McGranahan, Gale. 2002. Walnut Diseases, pp. 76-77. In: B.L. Teviotdale, T.J. Michailides, and J.W. Pscheidt (eds), Compendium of Nut Crop Diseases in Temperate Zone, APS Press.


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

Outputs
Our goal is to provide the California walnut industry with superior varieties through breeding and genetic engineering. It is proceeding swiftly due to the enthusiasm of participants at our annual crack-out meeting and the first Walnut Breeding Day. In the field we evaluated almost 2000 trees and cracked out nut samples from over 1300. We have 10 grower field trials underway and several more planned including a 6-acre block at Delta College. 29 new selections were identified at the crack-out meeting in March, bringing the total to 51. Many of these are targeted for general areas of the state, for example early harvest regardless of leafing date for the South and low blight for the North. In the coming year we expect to have commercial quality selections for resistance to blackline for the central area. Cross-pollinations this year were severely damaged by the spring frost, bagged flowers being more damaged than the surrounding shoots, resulting in only a few hundred seed. Laboratory work including improvements in micropropagation was highly successful. The media and conditions for the induction phase of rooting were optimized and the problem of rosetting after acclimatization in the greenhouse was solved. Transgenic lines expressing or silencing the polyphenol oxidase gene for insect resistance and rootability were developed and plantlet tests are underway in the Entomology Department. We also cooperated in the crown gall research of Dandekar and Escobar, aflatoxin research with USDA and generated embryos for testing oil content for the Labavitch lab.

Impacts
New walnut cultivars have had a major impact on walnut production in the US. The majority of trees now planted are derived from UC breeding programs. The patent approval process is still in progress for 'Robert Livermore' a red kerneled walnut that can serve a niche market or may prove to have a wider impact.

Publications

  • Leslie, CA, GH McGranahan, AM Dandekar, SL Uratsu, PV Vail, and JS Tebbets. 2001. Development and field testing of walnuts expressing the cry1Ac gene for Lepidopteran insect resistance. Acta Hort 544:195-200.
  • McGranahan, Gale, Chuck Leslie, Chris Christofferson, Joseph Wood, Wilbur Reil, Bill Olson, and Bob Beede. 2001. Walnut improvement program - 2000. Walnut Research Reports 2000, Walnut Marketing Board, pp. 3-18.
  • Christofferson, Chris, Gale McGranahan, Nick Mills, and Charles Leslie. 2001. The influence of walnut hull and shell morphology on codling moth, Cydia pomonella susceptibility. Walnut Research Reports 2000, Walnut Marketing Board, pp. 19-31.
  • Dandekar, Abhaya M., John M. Labavitch, Gale H. McGranahan, Sandra L. Uratsu, Carl Greve, and Charles Leslie. 2001. Characterization of seed-specific genes that regulate polyunsaturated oil composition and quality in walnut. Walnut Research Reports 2000, Walnut Marketing Board, pp. 33-61.
  • Reil, Wilbur, Joe Grant, Richard Buchner, Bob Beede, Janine Hasey, Gale McGranahan, Jim McKenna, Bruce Lampinen, and Cyndi Gilles. 2001. Paradox diversity study - orchard trials. Walnut Research Reports 2000, Walnut Marketing Board, pp. 79-91.
  • Olson, Bill, Jim McKenna, Gale McGranahan, Jed Walton, and Nick Bertagna. 2001. Walnut rootstock trial --2000. Walnut Research Reports 2000, Walnut Marketing Board, p. 107.
  • Lampinen, B., W. Micke, B. Beede, W. Coates, J. Edstrom, R. Elkins, M. Freeman, J. Grant, J. Hasey, L. Hendricks, K. Kelley, W. Krueger, W. Olson, W. Reil, S. Sibbett, G. Browne, G. McGranahan, B. Teviotdale, and J. Yeager. 2001. Walnut orchard management: Pilot projects, field testing, adaptive research and problem solving by C.E. Farm Advisors and Specialists. Walnut Research Reports 2000, Walnut Marketing Board, pp. 117-123.
  • Escobar, Matthew A., Sandra L. Uratsu, Edwin L. Civerolo, Gale H. McGranahan, Charles A. Leslie, and Abhaya M. Dandekar. 2001. Development of a crown gall resistant walnut rootstock. Walnut Research Reports 2000, Walnut Marketing Board, pp. 401-413.
  • Browne, Greg, Harold Becherer, Joe Wakeman, Joe Grant, Tom Burchell, Peter Viss, Jim McKenna, Chuck Leslie, Gale McGranahan, Dan Potter, and Wilbur Reil. 2001. Strategies for management of phytophthora on walnut: Evaluating potential of elite paradox clones and wingnut families. Walnut Research Reports 2000, Walnut Marketing Board, pp. 429-436.


Progress 01/01/00 to 12/31/00

Outputs
The goal of the Walnut Improvement Program is to breed and engineer new walnut cultivars and rootstocks that serve the needs of the US walnut industry. Total selections in the breeding program now are 19; these have a range of leafing dates but primarily an early harvest date. These selections are derived from Phase 1 of the breeding program in which all but the chosen pollen is excluded from the receptive flowers. Phase 2 of the breeding program, started in 1997, was designed to produce more seedlings for evaluations, but with less certainty of the male parent. In Phase 2 breeding, pollen of the selected males is blown onto the receptive but unbagged female flowers. Over 1100 seedlings from Phase 2 were propagated this year bringing the total. to over 3,200. This is in addition to 800 new seedlings generated in the backcross breeding program for hypersensitivity to the cherry leafroll virus. Walnut trees in our two transgenic blocks have come into bearing. The anther-derived Chandler clones appear true-to-type, thus demonstrating that mature cultivars can be transformed.

Impacts
New walnut cultivars have had a major impact on walnut production in the US. The majority of trees now planted are derived from UC breeding programs. The patent approval process is still in progress for 'Robert Livermore', a red kerneled walnut that can serve a niche market or may prove to have a wider impact.

Publications

  • Escobar, Matthew A., Jae-In Park, Vito S. Polito, Charles A. Leslie, Sandra L. Uratsu, Gale H. McGranahan, and Abhaya M. Dandekar. 2000. Using GFP as a scorable marker in walnut somatic embryo transformation. Annals of Botany 85:831-835.


Progress 01/01/99 to 12/31/99

Outputs
The goal of the Walnut Improvement Program is to breed and engineer new walnut cultivars and rootstocks that serve the needs of the United States walnut industry. Needed traits include pest and disease resistance and earlier harvest dates. Six new selections were identified this year and grafted into 3 selection blocks. The first nuts have been harvested from transgenic trees and a more representative harvest is expected this year. Genes were inserted to modify walnut oil composition and embryos of several lines are being tested.

Impacts
New walnut cultivars have had a major impact on walnut production in the US and we continue to select improved types. This year we released a new red kerneled walnut, "Robert Livermore", patent pending, that can serve a niche market or may prove to have much wider impact in both the food and health industries.

Publications

  • McGranahan, G.H., Leslie, C.A., McKenna, J.R., Reil, W.O. 1999. Walnut breeding and evaluation. Walnut Research Reports 1999. Walnut Marketing Board, Sacramento. pp 3-31.
  • Dandekar, A.M., Labavitch, J.M., McGranahan, G.H., Uratsu, S.L., Greve, C. and Leslie, C.A. 1999. Characterization of seed-specific genes that regulate polyunsaturated oil composition and quality in walnut. Walnut Research Reports 1999. Walnut Marketing Board, Sacramento. pp 33-68.


Progress 01/01/98 to 12/31/98

Outputs
The goal of the Walnut Improvement Program is to breed or engineer new walnut cultivars that serve a need in the walnut industry and to develop germplasm, knowledge and tools for future breeding efforts. Traits targeted for improvement include pest and disease resistance, increased precocity and earlier harvest dates. Over 4,000 seedlings from controlled crosses are in the process of being evaluated. There are 5 new selections, two that harvest early and aimed for the in-shell market, one which appears to avoid the walnut blight disease, one with a red seed coat, and one with large high quality kernels. Field trials are underway with transgenic walnut trees containing: Ro1ABC for rootability; Bt for codling moth resistance; Xa21 for blight resistance; snowdrop lectin for nematode resistance; and "leafy" for precocity.

Impacts
(N/A)

Publications

  • WOESTE, K., MC GRANAHAN, G., AND BERNATZKY, R. 1998. Low correlation between genomic and morphological introgression estimates in a walnut breakdown. J. Amer. Soc. Hort. Sci. 123(1):In Press.


Progress 01/01/97 to 12/01/97

Outputs
The goal of the Walnut Improvement Program is to breed or engineer new walnut cultivars that serve a need in the walnut industry and to develop germplasm, knowledge and tools for future breeding efforts. Traits targeted for improvement include pest and disease resistance, increased precocity and earlier harvest dates. Over 3,000 seedlings from controlled crosses are in the process of being evaluated. There are 3 selections, the most advanced being UC76-80 which is out in grower trails. UC76-80 has high yields of light colored kernels but the shell seal is weak. UC87-186 and UC87-187 have been planted in selection blocks in Davis, Kearney, and Chico. The following genes have been engineered into walnuts and the resulting embryos or plants are in the evaluation process: RolABC for rootability; Bt for codling moth resistance; Xa21 for blight resistance; snowdrop lectin for nematode resistance; and "leafy" for precocity.

Impacts
(N/A)

Publications

  • DANDEKAR, A.M., MCGRANAHAN, G.H., VAIL, P.V., URATSU, S.L., LESLIE, C.A., AND TEBBETS, S. 1997. High levels of expression of full-length cryIA(c) gene from BACILLUS THURINGIENSIS in transgenic somatic walnut embryos. Plant Science (In Press
  • NICESE, F.P., HORMAZA, J.I., AND MCGRANAHAN, G.H. 1997. Molecular characterization and genetic relatedness among walnut (JUGLANS REGIA L.) genotypes based on RAPD markers. Euphytica (In Press)


Progress 01/01/96 to 12/30/96

Outputs
The goal of the Walnut Improvement Program is to breed or engineer new walnut cultivars that serve a need in the walnut industry and to develop germplasm, knowledge and tools for future breeding efforts. Traits targeted for improvement include pest and disease resistance, increased precocity and earlier harvest dates. Over 3,000 seedlings from controlled crosses are in the process of being evaluated. There are 8 selections, the most advanced being UC76-80 which is out in grower trials. UC76-80 has high yields of light colored kernels but the shell seal is weak. The following genes have been engineered into walnuts and the resulting embryos or plants are in the evaluation process: RolABC for rootability; Bt for codling moth resistance; Xa21 for blight resistance; snowdrop lectin for nematode resistance; and "leafy" for precocity. The genotype "SU2" formerly used in transformations was found to be weak and unable to thrive in the field.

Impacts
(N/A)

Publications

  • WOESTE, K., MCGRANAHAN, G. H., and BERNATZKY, R. 1996. Randomy amplified polymorphic DNA loci from a walnut backcross (JUGLANS HINDSII x J. REGIA) x J. REGIAU. J. Amer. Soc. Hort. Sci. 121(3):358-361.
  • WOESTE, K., MCGRANAHAN, G., and BERNATZKY, R. 1996. The identification and characterization of a genetic marker linked to hypersensitivity to the cherry leafroll virus in walnut. Molecular Breeding 2:261-266.


Progress 01/01/95 to 12/30/95

Outputs
Materials in the breeding program in 1995 include standards (n=12), selections (n=8), about 200 introductions from 16 different countries, and over 2,000 seedlings from the crosses. Introductions include 187 genotypes of established trees and 16 new seed collections from China, 57 seedlings from Kyrgyzstan and material from India, Pakistan, Korea, France, and eastern Europe. Materials in the backcross breeding program include 200 BC2 trees, 98 BC3 trees and 440 seed from BC3 crosses this year. We are using Woeste's K15 marker as an initial screen for hypersensitivity and approximately half of the seedlings tested so far are hypersensitive. Our major progress in genetic engineering include transplanting clones to the field under APHIS permit in Davis and in Fresno. Transgenic plants containing a new Bt construct have been regenerated and transformations are in progress with the rice Xa21 from Pam Ronald and the snowdrop lectin from Abhaya Dandekar. A major accomplishment this year is the initiation of somatic embryos from Chandler anther tissue. Although they appear normal and contain the normal diploid number of chromosomes, we will not be able to confirm their trueness-to-type until they are in the field producing Chandler nuts. They are already being used in transformations.

Impacts
(N/A)

Publications

  • NO PUBLICATIONS REPORTED THIS PERIOD.