Genome-wide association analysis and transcriptome reveal novel loci and a candidate regulatory gene of fatty acid biosynthesis in sesame (Sesamum indicum L.)

The regulatory mechanisms of fatty acid (FA) biosynthesis and triacylglycerols (TAGs) assembly remain largely misunderstood in sesame. Gas chromatography was used to analyze the natural variation in FA compositions and oil content (OC) in 400 sesame accessions grown in three different environments. The phenotypic data was associated with the newly released SNP data from whole-genome resequencing, and 43 significant loci for FA and OC were identified. Comparative transcriptomics analysis of high-OC and low-OC materials was performed, and 515 differentially expressed genes (DEGs) were identified across three seed developmental stages. By integrating the genome-wide association study (GWAS) and DEGs analysis, twenty candidate genes were identified, of which SiTPS1 (trehalose-6-phosphate synthase 1) has emerged as a key regulatory gene of FAs and TAGs metabolism in sesame. Overexpression of SiTPS1 in transgenic Arabidopsis influenced FA composition and significantly increased OC. Our study provides resources for the markers-based improvement of OC and quality in sesame and other crops.