烟草种质的SSR标记遗传多样性及青枯病抗性的关联分析

SSR marker-based genetic diversity analysis of tobacco germplasm and association analysis with resistance to bacterial wilt

烟草青枯病是影响烟草产质量的主要病害之一,开发出与烟草青枯病抗病性密切相关的优异等位基因,可加速抗病品种的选育进程。据此,本研究选用94份烟草种质材料作为研究对象,运用236个SSR标记对这些材料进行基因分型和群体结构分析,开展基于连锁不平衡的关联分析探测与青枯病抗性相关的分子标记。结果表明,236个SSR标记在94份烟草种质中检测到904个等位变异位点,平均每个SSR标记为3.83个位点;这些SSR标记的多态性信息量(PIC)值在0.1361～0.8760之间,平均为0.5136。基于SSR基因分型数据,构建了126个标记单倍型;在此基础上进行群体结构分析,将94份种质划分为2个类群,表明本研究烟草种质的群体结构简单,有利于减少伪关联。二年田间抗病性数据与单倍型的关联分析发现7个单倍型与青枯病抗病性密切相关,其中有3个单倍型在二年的田间试验中均表现出与青枯病抗性密切相关,平均解释率超过10%。研究结果可为烟草青枯病抗病材料的分子标记辅助筛选提供参考。

Tobacco bacterial wilt(TBW)is one of the major diseases that affect tobacco yield and quality.The development of excellent alleles related to TBW resistance can accelerate the breeding process of resistant cultivar.In this study,94 tobacco germplasm materials were selected as research objects,of which the genotype and population structure were analyzed by using 236 simple sequence repeat(SSR)markers.Association analysis based on linkage disequilibrium(LD)was performed for identification of molecular markers associated with TBW resistance.The results showed that 236 SSRs detected 904 alleles in 94 tobacco germplasm materials,with an average of 3.83 alleles per SSR.The polymorphism information content(PIC)values obtained by SSR markers ranged from 0.1361 to 0.8760,with an average of 0.5136.Based on the SSR genotyping data,126 haplotypes were constructed.On this basis,the population structure was analyzed,with totally 94 germplasm materials being classified into 2 groups,indicating that the population structure was simple with relative narrow genetic background and could reduce false associations.Association analysis between haplotypes and TBW-resistant phenotyping data evaluated in two years of field trials showed that there were 7 haplotypes closely related to TBW resistance,and 3 of them showed close correlation with TBW resistance in both two years of field trials,with an averaged explanation rate over 10%.The results provided a reference for the marker-assisted selection of TBW-resistant materials in tobacco breeding program.