QTLs Mapping For Resistance To Fusarium Wilt And Some Agronomic Traits With A Gossypicum Hirsutum×G.Baberdense F₂ Population

Cotton plays an important role in the national economy of China, and Xinjiang is the most important quality cotton production region of China. Fusarium wilt, one of the most destructive disease in cotton, caused severely production decrease in many region including Xinjiang. It has been widely accepted that highly tolerant or resistant variety breeding is the most economical and effective method to deal with Fusarium wilt. However, traditional breeding procedure is quite time consuming for this objective. Since over a decade ago, molecular marker-assisted selection (MAS) has been regarded effective and helpful for desease resistance breeding. Thus MAS is perspected to be performed on cotton breeding of resistance to Fusarium wilt.In this research we mapped the QTLs for resistance to Fusarium wilt, and some other agronomic traits as well, with an interspecific hybrid cotton F2 populatioin by using SSR molecular markers. The results are as follows:1. A sea-island cotton cultivar Hai 7124, which is high resistant to Fusarium wilt, and an high sensitive upland cotton cultivar Junmian 1 were crossed and F1 plants were self-pollinated to produced 148 F2 individuals. A linkage map covering 673.3 cM with 56 loci, and average interval distance of 17.3 cM, was constructed based on the F2 population. The disease grades of Fusarium wilt were investigated at seedling and maturity stages. The QTL mapping and estimation of their genetic effects were performed with the combination interval mapping method. No resistance QTL was detected at seedling stage. Four resistance QTLs were detected at maturity stage and localized on the D12, A9 and D10 chromosome. The contributions to phenotypic variation of these QTLs were from 7.35% to 36.38%.2. Based on the same genetic linkage map mentioned above, QTL mapping analysis was performed for six agronomic traits, including the first fruit node, node number, boll number, boll weight, lint percentage and leaf area. Three putative QTLs with LOD≥2.5 were detected: including a QTL for lint percentage located on D10 chromosome, a QTL for node number on D12 chromosome, and a QTL for leaf area on linkage group LG6. The contributions to phenotypic variation of these QTLs were from15.33%-21.24%. These QTLs were suggested practically useful for MAS for cotton in the future.