2011 Annual Report
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.
Consumers of carrots in the United States (U.S.) benefit from nutrients of the crop, especially orange carotenoid pigments that provide dietary vitamin A. Root-knot nematodes are a major limitation to production of an acceptable carrot crop in much of the U.S. growing area, so the search for improved sources of genetic resistance is ongoing. Of the crosses within and between nematode resistant materials and other sources of resistance, populations with a high incidence of strong Meloidogyne incognita resistance were observed. F2 average scores were low in several populations from field trials, and in many populations with higher average scores, roots with low (resistant) scores were selected. Currently, greenhouse seed production is underway for selected roots from trials with resistance. These materials will be used to determine if multigenic resistance can be widely incorporated into carrots with limited use of nematicides. Of particular interest are nutritional properties in populations with elite nematode resistance. Quality components include color, smoothness, flavor (sweetness and harshness), texture, and nutritional value (carotene and anthocyanin pigment levels). A range in color and nutritional value has been evaluated in these materials that indicates nutritional quality or flavor will not need to be sacrificed to incorporate nematode resistance, and new color combinations with unique nutritional value will be developed. Over 1000 carrot deoxyribonucleic acid (DNA) samples were collected and molecular marker evaluation Amplified Fragment Length Polymorphism (AFLP), Simple Sequence Repeat (SSR), and Single-nucleotide polymorphism (SNP) is underway. Project monitored by regular meetings and e-mail discussions of progress.