Molecular Tagging of a Major Quantitative Trait Locus for Broad-Spectrum Resistance to Verticillium Wilt in Upland Cotton Cultivar Prema

Verticillium wilt (VW) is one of the important damaging cotton (Gossypium hirsutum L.) diseases worldwide. The use of resistant cultivars has long been considered as the most practical and effective means of controlling VW. The upland cotton cultivar Prema has high VW resistance and is useful for breeding new cultivars resistant to VW. To tag the resistance quantitative trait loci (QTL) in this cultivar, a population of 180 recombinant inbred lines was developed via single seed decent from a cross between the resistant Prema and the susceptible cultivar 86-1. Verticillium wilt resistance trials were conducted in the artificial disease nursery inoculated with mixed isolates and greenhouse individually with VW defoliating isolates V 991 and V D8 over a 2-yr period. Based on composite interval mapping analysis of the 2010 and 2011 data sets of adjusted disease reaction in the artificial disease nursery, seven resistant QTL were detected. Among them, one major VW-resistant QTL, which explained 62.83% of the phenotypic variation on the average with logarithm of the odds scores ranging from 23.37 to 26.73, was detected consistently and anchored on chromosome (chr.) D9. Greenhouse experiments revealed the existence of five significant QTL on chr. A9, D3, D11, and D9. Our results showed that qVW-D9-1 is a major broad-spectrum VW resistance QTL. Identification of this QTL will facilitate the marker-assisted selection of VW resistance in cotton breeding.