1a.Objectives (from AD-416)
Deployment of nematode resistant carrots to U.S. growers and seed industry.
1b.Approach (from AD-416)
We have discovered multiple genetic sources of nematode resistance in carrot germplasm. In this project we will confirm the strength of the resistance, intercross best resistance, produce ample seed for extensive field testing, and release best resistance to the public, especially growers and seed companies. We will also evaluate horticultural quality including field performance traits (color, shape, uniformity) and consumer quality (flavor and nutritional value), hold field days for the carrot production community, and confirm genetic models of resistance in mapping populations.
Root-knot nematodes cause significant levels of economic loss for United States (U.S.) carrot growers. Extensive evaluation of the strength of the nematode resistance has been made at two infested field screening sites, and in greenhouse screening, with extreme nematode pressure. The resistance from original Brazilian sources as well as a new source of resistance derived from a Syrian carrot was found to hold up very well. Other sources of resistance identified several years ago are still being evaluated and hold some promise. A new source of resistance from a wild carrot is also being evaluated to determine gene action. Segregating populations incorporating combinations of resistance, or intercrossing resistance into long, high color, good flavor susceptible backgrounds have been established and advanced in the breeding program. Seed was produced from several F2 and F3 populations that combine multiple sources of resistance. Inheritance studies underway provide basic scientific information and the basis for development of molecular markers which seed companies, and our program can use to incorporate resistance into carrot germplasm backgrounds. Project monitored by regular meetings and e-mail discussions of progress.