ICRISAT花生微核心种质农艺性状和黄曲霉抗性关联分析

Association Analysis of Agronomic Traits and Resistance to Aspergillus flavus in the ICRISAT Peanut Mini-Core Collection

以国际半干旱热带地区作物研究所(ICRISAT)花生微核心种质146份资源为材料,鉴定农艺性状和黄曲霉抗性,用26对SSR引物检测多态性位点,在分析连锁不平衡、群体结构和Kinship的基础上进行关联分析。连锁不平衡的分布显示R2平均值为0.185,表明26对SSR引物扩增的120个位点之间具有较低的连锁不平衡程度。群体结构分析结果将146份花生品种分为2个亚群,分别对应疏枝亚种和密枝亚种,与植物学分类和遗传分化分析的结果基本一致。关联分析表明,共有39个位点与10个农艺性状(株高、总分枝数、第一分枝数、小叶宽、结果分枝数、百果重、出仁率、单株生产力、种子长、种子宽)相关联,表型变异解释率为1.50%～20.34%,16个SSR位点与黄曲霉侵染病情指数、黄曲霉产毒量相关联,表型变异解释率为5.23%～17.19%,与农艺性状、黄曲霉抗性同时相关联的SSR位点有13个。关联位点的等位变异效应分析表明,10个农艺性状和2个黄曲霉抗性性状共有63个增效等位变异和47个减效等位变异,并发掘了ICG6022等携有优良等位变异的载体品种。

Yield is an important trait in peanut breeding, which is strongly influenced by environments and complex genetic fac- tors. Association mapping, based on natural population and linkage disequilibrium （LD）, has been successfully used for exploring the genetic basis of complex traits in crops. In this study, we introduced a set of peanut mini-core collection of 146 varieties from International Crops Research Institute for the Semi-Arid Tropics （ICRISAT）, which were phenotyped for agronomic traits and resistance to Aspergillus flavus and genotyped by using 26 SSR primers containing 120 loci in the population. Based on the analyses of linkage disequilibrium, population structure and kinship, we performed the genome-wide association mapping. Dis- tribution of LD suggested that the average of the total R2 was 0.185, indicating a relative low level of LD between the SSR loci. One hundred sixty-four varieties were grouped into two subgroups by population structure analysis corresponding to Arachis hy- pogaea ssp. fastigiata and Arachis hypogaea spp. hypogaea, respectively, which was consistent with botanical classification and results of analysis of genetic differentiation. A total of 39 loci were identified to be associated with ten agronomic traits, with 1.50-20.34% of phenotypic variation explained. A total of 16 loci were associated with Aspergillus flavus infection index and aflatoxin amount, with 5.23-17.19% of explained phenotypic variation. Of which, 13 common loci were associated with both agronomic traits and resistance to Aspergillus flavus. Furthermore, 63 alleles with increasing effect, 47 alleles with decreasing effect and the varieties carrying them were identified for ten agronomic and two resistance-related traits. This study demonstrates that association mapping is effective to explore genetic basis of important traits in peanut and assist to peanut breeding.