2012 Annual Report
1a.Objectives (from AD-416):
Our objective is to develop landmark cultivars, advanced breeding lines and information for use by other breeders, scientists, producers and growers. This research will emphasize developing resistance to diseases, insects, and physiological defects, as well as the development of molecular markers for genetic analysis and marker assited selection.
1b.Approach (from AD-416):
Problems facing the lettuce industry will be addressed using genetic approaches in field, greenhouse, and laboratory experiments that are suited to coastal, desert, and interior valley locations, to the various types of lettuce, and to the demands of different production and marketing approaches.
The agreement was established in support of objective 1 of the in-house project, the goal being to incorporate valuable traits into crisphead, mixed lettuce, and spring mix cultivars and breeding lines that are adapted to coastal California and low desert production conditions. This project is monitored through twice yearly written and oral reports. Our objectives are to incorporate resistance to several diseases, insects, and physiological defects into iceberg, romaine, and mixed lettuce cultivars and breeding lines adapted for coastal and low desert production. In the 2011-2012 period, major efforts targeted resistance to lettuce big vein disease, lettuce drop caused by Sclerotinia species, Verticillium wilt, lettuce dieback/tombusviruses, bacterial leaf spot, corky root, downy mildew, leafminer, lettuce aphid, tipburn, shelf-life of salad-cut lettuce, and multiple disease resistance. Minor programs addressed resistance to yellow spot. In all programs, horticultural traits, adaptation, and resistance to tipburn are essential. Selections were taken from breeding populations and advanced breeding lines were evaluated as part of breeding for resistance to big vein disease, downy mildew, lettuce drop, Verticillium wilt, dieback, bacterial leaf spot, corky root, leafminer, tipburn, and pre-mature bolting. Genetic studies concurrent with breeding programs are being conducted to determine the inheritance of resistance to big vein disease, bacterial leaf spot, dieback, leafminers, downy mildew, lettuce aphid, corky root, shelf-life of salad-cut lettuce, and Verticillium wilt. Publications during 2011-2012 included reports of original research on Verticillium wilt, downy mildew, leafminer, lettuce aphid, shelf-life, resistance to the fungicide triforine, and novel approaches to evaluate disease progress and combine phenotypic data from multiple trials.