Meloidogyne incognita nematode resistance QTL in carrot

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 Meloidogyne 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 × HM1) and (SFF × HM2), as well as a segregating population derived from the self-pollination of a HM plant (HM3). Analysis revealed four QTLs conditioning resistance in Br1091 × HM1, three in SFF × 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 three populations, in the same region of chromosome 8 as Mj-1 which imparts resistance to M. javanica.