Association mapping of resistance to Verticillium wilt in Gossypium hirsutum L. germplasm

Abstract

Verticillium wilt is a major disease affecting the growth of cotton. For screening the resistant genes, 320 Gossypium hirsutum germplasms were evaluated in Verticillium nursery, and association mapping was used to detect the markers associated with the Verticillium wilt resistance. 106 microsatellite marker primer pairs were used to estimate the genetic diversity, population structure and linkage disequilibrium (LD) of the germplasm. Polymorphism (PIC) was found to be 0.53, and population structure were detected to be three subgroups (K=3). LD decay rates were estimated to be 13 to 15cM (r² ≥0.20). Significant associations between polymorphic markers and Verticillium wilt resistance traits were observed using the general linear model (GLM) and mixed linear model (MLM). Four loci showed positive effects on the phenotype which meant that these loci could promote the Verticillium wilt resistance of cotton, and thirteen loci showed negative effects in GLM. The results displayed that association mapping could complement and enhance quantitative loci (QTLs) information for marker-assisted selection in cotton breeding.

Keywords: Cotton germplasm, verticillium wilt, simple sequence repeats (SSR) markers, linkage disequilibrium (LD), association analysis

African Journal of Biotechnology, Vol 13(31) 3165-3172