Mapping and quantitative trait loci analysis of verticillium wilt resistance genes in cotton.

Verticillium wilt is one of the most serious constraints to cotton production in almost all of the cotton-growing countries. In this study, "XinLuZao1" (XLZ1), a susceptible cultivar Gossypium hirsutum L. and "Hai7124" (H7124), a resistant line G. barbadense, and their F(2:3) families were used to map and study the disease index induced by verticillium wilt. A total of 430 SSR loci were mapped into 41 linkage groups; the map spanned 3,745.9 cM and the average distance between adjacent loci was 8.71 cM. Four and five quantitative trait loci (QTLs) were detected based on the disease index investigated on July 22 and August 24 in 2004, respectively. These nine QTLs explained 10.63-28.83% of the phenotypic variance, six of them were located on the D sub-genome. Two QTLs located in the same marker intervals may partly explain the significant correlation of the two traits. QTLs explaining large phenotypic variation were identified in this study, which may be quite useful in cotton anti-disease breeding.