Fine Mapping a Major QTL Controlling RKN Reproduction on Chr14 in Upland Cotton

In an earlier study, we identified two major QTLs controlling root-knot nematodes resistance in the M-120 RNR by Pima S6 population. The QTL on Chr 11 appears to confer reduction in root galling, while the QTL on Chr14 mostly involved in suppressing nematodes egg reproduction.  The objective of this study was to fine map the QMi-C14 and to further investigate the hypothesis of independent resistance genes in controlling plant responses to suppression of root galling and eggs reproduction. Seven genetically similar populations were developed from 7 F2 individuals of the M-120 RNR by Pima S6 cross carrying only the resistance gene on Chr 14. QTL analysis using the non-transformed data showed that a QTL was significantly associated with root galling index, total eggs, and eggs/g root, accounting for 17.8%, 33.3% and 24.4% of the phenotypic variation, respectively. However, if the log-transformed data was used, this QTL was only associated with total eggs and eggs/g root, accounting for 29.2% and 17.9% of the phenotypic variation, respectively.  Finally, the Mi-C14 locus was mapped to a 5.7-cM interval flanked by the SSRs marker.