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United States Department of Agriculture

Agricultural Research Service

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Research Project: Next-Generation Lettuce Breeding: Genes to Growers

Location: Crop Improvement and Protection Research

2012 Annual Report

1a. Objectives (from AD-416):
To determine the inheritance of field resistance to downy mildew, tipburn resistance, sclerotinia resistance, and shelf-life in multiple genetic mapping populations. To identify sources of physiological resistance to sclerotinia. To develop genetically improved lines of lettuce for downy mildew resistance, sclerotinia resistance, tipburn resistance, and shelf-life.

1b. Approach (from AD-416):
The research to be conducted involves developing and analyzing multiple recombinant inbred line populations (RILs) to identify genes and QTL for field resistance to downy mildew, scelertinia resistance, tip burn resistance and extended shelf-life. The RILS wil be evaluated in field and greenhouse experiments, genotyped with molecular marker, analyzed to determine the inheritance traits, and markers suitable for markers assisted selection will also be developed. There is also research to develop improved in vitro and greenhouse methods for sclerotinia resistance.

3. Progress Report:
The agreement was established in support of objective 1 of the in-house project, the goal being to determine the genetic basis of horticulturally important traits in lettuce and develop commercially-useful molecular markers for horticulturally important genes. The USDA contributes to the following objectives of this project. 1) determine the genetic basis of horticulturally important traits in lettuce. 2) develop commercially-useful molecular markers for horticulturally important genes and to release these markers to make MAS (marker assisted selection) available to the lettuce breeding industry. 3) develop and release advanced lettuce breeding lines and landmark cultivars of all lettuce types that are resistant to multiple diseases and have superior horticultural characteristics including: wide adaptability, improved color and nutritional quality, extended shelf-life, are slow bolting, and have tipburn resistance. 4) train students, postdocs, and commercial breeders to operate in a data-rich environment. This project is monitored using conference calls, email, and biennial meetings. We selected, contributed, and assisted evaluation of lettuce germplasm in a field experiment for nitrogen use efficiency and water use efficiency. We determined the inheritance of decay of salad-cut lettuce in modified atmosphere packaging in two independent populations. Progress was made in developing molecular markers to select for slow decay using marker assisted selection. A post-doc was mentored on research to determine the inheritance of resistance to race 2 isolates of V. dahliae. Advanced breeding lines from the USDA and UC breeding populations were evaluated in replicated field experiments to evaluate multiple horticultural and quality traits.

4. Accomplishments

Last Modified: 08/16/2017
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