Molecular diversity and identification of alleles for Verticillium wilt resistance in elite cotton (Gossypium hirsutum L.) germplasm

Cotton is an important crop in the textile, food and pharmaceutical industries. In the present study, a panel of 108 elite cotton (Gossypium hirsutum L.) lines was genotyped with 177 genome-wide SSR markers to assess genetic diversity, linkage disequilibrium, population structure and association analyses. A total of 967 loci were assayed and the lines fell into four main groups with a mean genetic distance of 39%. The linkage disequilibrium (LD) decay rate was estimated to be 20–30 cm (r2 ≤ 0.5). Association analyses were performed with both general linear model and mixed linear model methods to identify SSR marker loci linked to Verticillium wilt resistance. Verticillium wilt is a fungal disease that causes huge yield losses in cotton production throughout the world. A total of 26 marker loci distributed on 14 chromosomes were associated with resistance at p ≤ 0.05. Eight of the 26 associated marker loci were highly significant (p < 0.01). The phenotypic variation explained (r2) by individual markers ranged from 3.2% to 8.2%. Three of the 26 marker loci (JESPR153, JESPR274 and CIR218) were consistent with previous studies. Our results should be useful in improving Verticillium wilt resistance in cotton breeding lines.GDARP (General Directorate of Agricultural Research and Policies, Ministry of Food, Agriculture and Livestock Republic of Turkey) (TAGEM-11/AR-GE/17