The Research On The Cotton Anti-verticillium Wilt Molecular And The Important Agronomy Trait QTLs

The cotton verticillium wilt, which has become a main obstacle for high and stable yield in cotton, is called "the cancer of cotton" in China. Therefore it's urgent to study the molecular genetics for cotton verticillium wilt. In present research, QTLs for anti-verticillium wilt and important agronomic traits were mapped by using SSR molecular makers in F₂ populations. The genetic effects for single locus were also studied. This study will help to promote the development of molecular assisted selection in cotton breeding for anti-verticillium wilt.1. Two F₂ population derived from the intraspecific cross of the highly tolerant Gossypium hirsutum cv (Xinluzhong10) and the susceptible G. hirsutum cv (Junmianland xinluzhao7) which phenotyped as non-defoliating V. dahliae were used in present research. By MAPMAKER/EXP (Version3.0b) made use two linkage map,the minLOD with three, the maxheredity-distamce with 50 cM.the two genetic linkage maps comprised of 156 loci covered 1465.8 cm genetic distance, approximately 26.65% of the whole cotton genome. Two different disease outbreak peaks of verticillium wilt during the period of guitar bolls and wadding and seedling appraisal were scanned by composite interval mapping, with LOD threshold 2.5. Three QTLs related to resistance were detected on three different linkage groupst and explained 14.2%-48.4% of the trait variation, indicating that the resistance of V.wiltis was controlled by polygenes. Three QTLs susceptible to v-wilt were also detected and explained 11.3%, 12.9%,45.2% of the trait variation. However, all the three QTLs were linked with maker NAU 1211, which indicated that it might be the same locus.2. QTLs for seven agronomic traits, including first fruit nodes, boll weight, lint percentage seed index, plant height, main-lobe length and the second-lobe were mapped in two F₂ populations. Totally 17 stable QTLs, one for first fruit nodes and explained 7.0% of the trait variation, two for plant height and explained 7.5%,23.1 % of the trait variation, three for seed index and explained 9.7%-18.8% of the trait variation, four for lint percentage and explained 6.5%-11.9% of the trait variation, three for boll weight and explained 11.6%-14.7% of the trait variation, four for main-lobe and second-lobe were detected in two populations and explained 10.7%-21.5% of the trait variation.