Association Analysis Of Senescence-related Trait, Resistance To Verticillium Wilt In Upland Cotton

Most of agronomic traits of upland cotton such as yield, early maturity, resistance of verticillum wilt and fiber quality are quantitative traits. QTL mapping and association mapping are two main efficient strategies to dissect the genetic basis of complex quantitative traits. In this study, 186 samples of upland cotton materials were planted at two sowing data. Penotypes of four environments were used to perform association analysis of 3 traits related early senescence(Margin of boll weight, the number of upper boll and chlorophyll content) and resistance of verticillum wilt using SSR markers to detecting SSR loci that significantly association with these traits. The main results were as follows:1. A total of 355 alleles were obtained from 140 SSR polymorphism SSR primers for the 186 materials by the genetic diversity analysis, with an average of 2.54 alleles per SSR primers. Polymorphism information content(PIC) of primers ranged from 0.503-0.995, with an average of 0.759. And it indicated that the selected primers could provide rich genetic information.2. By using the software of STRUCTURE 2.3.4 showed that 186 samples were divided into 2 subgroups. One is 96, and another is 90. In order to further association analysis, we calculated the Q value of each material.3. We selected two models, which referred to the general lineral model(GLM) included Q and the mixed linear model(MLM) included Q+K to correct for false positives. The results were better from the MLM model than the GLM model.4. The results were based on 140 pairs of SSR primers of genotype and phenotype of 186 samples by association analysis using GLM(P<0.001) and MLM(P<0.01).1) Ther were 33 SSR loci associated with chlorophyll content both in the GLM and MLM model. There were 3 loci(NAU998-3,PGML01548-1,CGR5258-3) could detect in multiple environments. The variation explanated by related markers were 6.55%, 5.84% and 5.93%.2) Ther were 5 SSR loci associated with the number of upper boll both in the GLM and MLM model. Two loci(MGHES-73-1 and NAU1230-1) could find in more than two environments. The variation explanated by related markers were 5.01% and 5.21%.3) Ther were 2 SSR loci(NAU1230-1 and NAU1255-1) associated with the Margin of boll weight both in the GLM and MLM model. The variation explanated by related markers were 5.21 and 3.98%.4) Ther were 22 SSR loci associated with resistance of verticillum wilt both in the GLM and MLM model. Two loci(NAU998-3 and CGR5258-3) could found in more than two environments. The variation explanated by related markers were 5.5% and 12.1%.5. Based on the analysis of genetic similarity, the cluster analysis showed that the 96 samples couldbe divided into 3 subgroups, and the GS(genetic similarity) among the 96 sanples ranged from 0.261 to 0.893. These results were basically agreed with the pedigrees and indicated low levels of genetic of diversity with upland cotton in China.