Genome-Wide Association Study Reveals Novel Loci and Candidate Genes of Vitamin E Content in Sesame (Sesamum indicum L.).

Sesame is a significant oilseed crop whose exceptional oxidative stability is closely associated with its abundant endogenous antioxidants. As one of the most predominant lipid-soluble antioxidants in sesame, vitamin E (VE) plays a critical role in scavenging lipid peroxyl radicals, terminating lipid peroxidation chain reactions, and protecting cellular membranes from oxidative damage, thereby maintaining intracellular redox homeostasis and attenuating the development of oxidative stress-related disorders. Although VE is a potent natural antioxidant with significant pharmacological activities in mitigating oxidative stress-related disorders, the genetic mechanisms underlying the natural variation in VE content in sesame remain incompletely understood. Here, variation in VE content was evaluated across 400 sesame accessions grown in two environments. Ultra-high-performance liquid chromatography (UHPLC) analysis revealed that only γ-tocopherol was detected in sesame seeds, with concentrations between 169.33 and 463.31 mg/kg, averaging 316.28 mg/kg. The newly acquired SNP and InDel data from whole-genome resequencing were associated with the phenotypic data, leading to the identification of five significant loci associated with VE content. Comparative transcriptomic profiling of two sesame accessions with distinct VE contents revealed the differential expression of key biosynthetic enzyme genes (such as GGDR, PDS1, VTE2, and VTE4) between the two accessions. By integrating a genome-wide association study with transcriptomic data, two primary candidate effector genes, SINPZ1100015/SiNST1 and SINPZ0901927, were identified, with SiNST1 being particularly prominent. Functional validation further showed that overexpression of SiNST1 in the hairy root of sesame significantly decreased VE content. This investigation advances the comprehension of variations in VE content and the regulatory mechanisms governing its biosynthetic metabolism in sesame, supporting the development of functional sesame varieties for dietary antioxidant supplementation.