Genome-wide association study of oil content and fatty acid composition in sesame (Sesamum indicum L.) under diverse environmental conditions

Sesame (Sesamum indicum L.) is a valuable oilseed crop that is widely grown in tropical and subtropical regions because of its high oil content and favorable fatty acid profile. This study evaluated 200 genetically diverse genotypes in two distinct environments (Abu-Naama and Matuq) using an augmented block design. We employed three genome-wide association study (GWAS) models (fixed and random model circulating probability unification [FarmCPU], Bayesian information and linkage-disequilibrium iteratively nested keyway [BLINK], and multiple locus mixed model [MLMM]) to dissect the genetic basis of the oleic acid, linoleic acid, and oil content. Across environments, significant single nucleotide polymorphism (SNP) markers explained 3%–23% of the phenotypic variance, reflecting the quantitative nature of these traits. Notably, four SNPs (Chr1_1693157, Chr3_23284702, Chr5_17024932, and Chr9_1711873) were common across all three models, suggesting stable and robust associations between oleic acid and oil content. Candidate gene analysis revealed four notable sequences linked to these loci: a transcription repressor OFP8 (Sesamum alatum), an HVA22-like protein, a 3-oxoacyl-[acyl-carrier-protein] synthase 3 A, and a putative phospholipid diacylglycerol acyltransferase 2 in (S. indicum), all of which may play key roles in oil biosynthesis and accumulation. Environment-specific loci have also emerged for linoleic acid, particularly on chromosomes 6, 9, and 13. These findings provide robust targets for marker-assisted selection and underscore the value of integrating multi-model GWAS and functional validation to develop elite sesame cultivars with improved oil quantity and quality.