Fine mapping QMi-C11 a major QTL controlling root-knot nematodes resistance in Upland cotton.

The identification and utilization of a high-level of host plant resistance is the most effective and economical approach to control root-knot nematode (Meloidogyne incognita). In an earlier study, we identified a major quantitative trait locus (QTL) for resistance to root-knot nematode in the M-120 RNR Upland cotton line (Gossypium hirsutum L.) of the Auburn 623 RNR source. The QTL is located in a 12.9-cM interval flanked by the two SSR markers CIR069 and CIR316 on the distal segment of chromosome 11. To construct a fine map around the target region, a bulked segregation analysis was performed using two DNA pools consisting of five individuals, with each being homozygous for the two parental alleles. From a survey of 1,152 AFLP primer combinations, 9 AFLP markers closely linked to the target region were identified. By screening an additional 1,221 F(2) individuals developed from the initial mapping population, the Mi-C11 locus was delimited to a 3.6-cM interval flanked by the SSR marker CIR069 and the AFLP marker E14M27-375. These results further elucidate the genetic fine structure of the Mi-C11 locus and provide the basis for map-based isolation of the nematode resistance gene in M-120 RNR.