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Title: Meloidogyne incognita nematode resistance QTL in carrot

item PARSONS, JOSHUA - University Of Wisconsin
item MATTHEWS, WILLIAM - University Of California
item IORIZZO, MASSIMO - University Of Wisconsin
item ROBERTS, PHILIP - University Of California
item Simon, Philipp

Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/6/2014
Publication Date: 4/21/2015
Publication URL:
Citation: Parsons, J., Matthews, W., Iorizzo, M., Roberts, P., Simon, P. 2015. Meloidogyne incognita nematode resistance QTL in carrot. Molecular Breeding. 35(5):114. doi: 10.1007/s11032-015-0309-2.

Interpretive Summary: Root-knot nematodes are a very important soil-borne pest attacking carrots, occurring in over 70% of the U.S. carrot production area. Nematode attack disfigures carrot roots and makes them unmarketable with even a small amount of infection. Nematicides control this pest but they are both expensive as well as harmful to farmers and the environment. Genetic resistance is one of the few possible means to protect carrots from nematode attack. In this study we evaluated root-knot nematode resistance in carrot breeding populations derived from intercrosses between parental breeding stocks from Brazil, Syria, and Europe known to have some level of genetic resistance to nematodes. We found genes for resistance on five carrot chromosomes, with very high levels of resistance with some combinations of these genes. This research is of interest to carrot researchers, carrot growers, vegetable breeders, environmental agencies, and consumers.

Technical Abstract: Root-knot nematodes (Meloidogyne spp.) are major pests attacking carrots (Daucus carota) worldwide, causing galling and forking of the storage roots, rendering them unacceptable for market. Genetic resistance could significantly reduce the need for broad-spectrum soil fumigants in carrot production. In this study genetic resistance to M. incognita was mapped. Three diverse sources of resistance, from Syria (HM), Europe (SFF) and South America (Br1091) were identified. Two F2 mapping populations were developed using these parents, (Br1091 x HM1) and (SFF x HM2), as well as a segregating population derived from the self-pollination of a HM plant (HM3). Analysis revealed four QTLs conditioning resistance inBr1091 x HM1, three in SFF x HM2, and three in HM3. A consensus genetic map of the three populations revealed five non-overlapping QTLs for M. incognita resistance, one each on carrot chromosomes 1, 2, 4, 8, and 9. One QTL was present in all 3 populations, in the same region of chromosome 8 as Mj-1 which imparts resistance to M. javanica.