Mapping of QTLs responsible for yield related traits in advance lines of cotton (Gossypium hirsutum L.).

Abstract

Cotton, an important fibre producing crop, enjoys a paramount position among all cash crops. But currently cotton plant is facing genetic erosion due to genetic bottleneck, whereas little effort is carried out in improving cotton genome. Recently many techniques are employed to improve yield to withstand abiotic as well as biotic stresses. Present study was carried out to find loci related to yield traits in cotton genome through association mapping technique. 45 varieties were selected from all over Pakistan and evaluated phenotypically for yield related traits. Correlation between phenotypic traits was calculated. Results of correlation showed that plants having greater number of bolls per plant, number of monopodial and sympodial branches, seed index, boll weight would help breeders to gain more yield. Population structure of all varieties was determined using SSR markers. STRUCTURE software was employed to obtain correct number of sub-populations in graphical form. STRUCTURE analysis divided population, first into 3 main groups and then into 8 groups. Each group showed admixture. General linear modal (GLM) was applied for association mapping. In this approach Q-matrix was used to compensate false positives. QTLs above LOD 2.5 were selected. Five markers gave suitable LOD score. Primer BNL4096 gave highest LOD score of 3.18 for character, yield per plant while primer NAU1070 showed 2.95 LOD score for fibre strength. We found some unique associations of loci with the yield traits of cotton. These associations can further be utilized in increasing the performance of cotton varieties.