Genome-wide association study (GWAS) identifies genetic loci and candidate genes for variation in protein and oil content in Sesamum indicum L.

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Sesame ( Sesamum indicum L.) is an ancient diploid oilseed crop valued for its high oil content, quality protein, unsaturated fatty acids, and antioxidants. The emerging research focuses on the utilization of vegetable proteins in the development of novel products and the formulation of functional foods. Developing sesame genotypes with higher protein and oil content is a current area of focus for improving sesame quality traits, as preferred by the sesame seed oil industry and consumers. Despite previous genome-wide association studies (GWAS) on various agronomic and biochemical traits in sesame, the genetic basis of protein content and fat remains limited. Therefore, this study was designed to identify candidate genes and quantitative trait loci (QTLs) regulating the target traits using 401 sesame accessions grown in three environments (2018WH, 2018LQ, and 2022WH). The protein and oil content in the sesame population varied significantly. The protein content ranged from 15.06% to 26.45%, while the oil content was between 41.68% and 60.15%. Furthermore, the white seeds had a higher oil content, while the black seeds had a higher protein content, indicating an association between seed colour and oil and protein content. GWAS results revealed that 632 and 269 QTLs were selected as significant genetic regions for protein and oil content, respectively. Of these significant QTLs, we identified 10 and 22 stable QTLs for protein and oil content, respectively. A total of 17 candidate genes related to protein and oil content were identified within 32 stable quantitative trait loci (QTLs). Interestingly, two variant sites, SNP13:10093594 and InDel13:10935497, related to protein content, were identified in the gene sequences of SINPZ1300586 and SINPZ1300694 . Four SNPs, SNP1:22608987, SNP4:13355820, SNP8:21686488, and SNP11:142842, for oil content were found correspond to the genes SINPZ0102106, SINPZ0401222, SINPZ0801731, and SINPZ1100015 , respectively. The findings provide light on the genetic basis of protein and oil characteristics. These genes and QTLs can aid the molecular breeding and genetic engineering of innovative sesame germplasm, with improved potential for protein and oil content, as well as desired quality attributes.