棉花资源群体结构的推测与纤维品质的关联分析

Population structure inferring and association analysis of fiber quality in cultivated cotton

【目的】推测棉花资源群体材料的基因组血统与分子亲缘关系,并通过关联分析检测群体中影响表型的位点,为优质纤维品种的选育及其效率的提高提供理论依据。【方法】利用均匀分布于26条染色体上的132个SSR标记,对经挑选的92份栽培棉材料的基因组变异进行扫描,利用STRUCTURE 2.3.1软件的混合模型聚类法分析该群体的遗传结构,采用NTSYS-pc（Version 1.8）软件进行UPGMA聚类,随后采用TASSEL软件的GLM（General linear model）程序,对5个纤维品质性状2年×3重复的观测值进行标记与目标性状的关联分析。【结果】当指定7个亚群（K=7）时似然值达到最大,该群体分为亚洲棉组（Cluster 5）、海岛棉组（Cluster 7）、陆地棉1~3组（Cluster 2、Cluster 4和Cluster 6）、混合血统组（Cluster 1和Cluster 3）。组群间的Kullback-Leibler和UPGMA聚类图显示了7个组群的遗传组成和材料间的分子亲缘关系。关联分析表明,该群体中累计有21个位点与目标性状相关,一些标记同时与2个或多个目标性状相关联,可能是目标性状相关乃至＂一因多效＂的遗传基础。【结论】明确由92份材料组成的自然群体的群体结构以及材料间的亲缘关系,并获得了21个与棉花纤维品质相关的SSR位点,将为这些育种材料的利用、标记辅助选择及下一步候选基因的关联作图提供参考信息。

【Objective】 The major objective was to infer the genome ancestry and the estimation of molecular relation in natural population,and then to detect the loci controlling the interested traits by means of association analysis,so as to lay a theoretic foundation for the effective improvment of fiber quality and the heightenning of breeding efficiency.【Method】 One hundred and thirty-two SSR loci,evenly distributed in 26 chromosomes,were assayed for polymorphism among 92 cultivated cotton accessions which represent the high genetic diversity.The identified 494 alleles served as raw data for estimating population structure based on the ADMIXTURE model in the software STRUCTURE 2.3.1.The UPGMA dendrogram was calculated using the software of NTSYS-pc（Version 1.8）.Then,the association analysis between SSR loci and 5 fiber quality traits（2 years×3 replicate） was performed by using TASSEL GLM（general linear model） program.【Result】 Specifying seven subpopulations（K=7） led to a maximum likelihood value.Therefore,this natural population was inferred to be composed of 7 subpopulations,which were Gossypium arboreum（Cluster 5）,G.barbadense（Cluster 7）,G.hirsutum（Cluster 2,Cluster 4 and Cluster 6）,and mixture（Cluster 1 and Cluster 3）.The Kullback-Leibler distance of pairwise subpopulation was also inferred as the UPGMA dendrogram,which gave a detailed percentage of genetic composition of seven subpopulations and molecular relatedness of each accession.And twenty one SSR loci associated with the traits were screened out from this cultivated population.There were a few loci associated with two or more traits simultaneously,which might be the genetic reason of correlation among traits or pleiotropic phenomena.【Conclusion】 The population structure of this natural population and the molecular relatedness of each accession were inferred;twenty one SSR loci associated with the traits were detected.These results would provide some referenced information for the utilization of these accessions,for marker assisted selection（MAS）,and for the upcoming association studies of some candidate genes.