2010 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. 3.Progress Report Consumers of carrots in the 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. Field screening for nematode resistance in 55 carrot populations yielded plants with superior resistance, including 3 populations with very high resistance in plants derived from a Brazilian source. Two carrot populations from an intercross between a Syrian source of nematode resistance with both a new South American resistance source and a new European resistance source resulted in segregating for resistance. Both populations exceeded 140 plants which are being evaluated for resistance and to initiate a marker-assisted selection program. 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.