Dissection of the genetic basis of oil content in Chinese peanut cultivars by association mapping

Abstract

Background Peanut is one of the primary sources for vegetable oil worldwide, and enhancing oil content is the main objective in these peanut breeding programs. Linked markers for oil content is required for use in genomics-assisted breeding (GAB), and association mapping is one of the promising approaches for discovery of associated markers. Results An association mapping panel consisting of 292 peanut varieties extensively distributed in China were phenotyped for oil content and genotyped with 583 polymorphic SSR markers. These markers amplified 3663 alleles with an average of 6.28 alleles per locus. The results of structure, phylogenetic relationship, and PCA analyses indicated two subgroups majorly differentiating based on geographic regions. Genome-wide association analysis using genetic and phenotypic data identified 12 associated markers including one (AGGS1014_2) highly stable association controlling up to 9.94% phenotypic variance explained (PVE) across multiple environments. Interestingly, the frequency of the favorable alleles for 12 associated markers showed a geographic difference. Two associated markers AGGS1014_2 and AHGS0798 with 6.90-9.94% PVE were verified to enhance oil content in an independent RIL population. The combined genotypes of AGGS1014_2 and AHGS0798 appeared to experience selection during the breeding program. Conclusion This study provided insights into the genetic basis of oil content in peanut and verified that two SSR markers were highly associated with oil content. Our results could facilitate marker-assisted selection for high-oil content breeding.