Integrative metabolomic and transcriptomic analyses reveal key mechanisms of lignan biosynthesis during sesame (Sesamum indicum L.) seed development

Sesame (Sesamum indicum) is a major oilseed crop known for its substantial amount of natural antioxidants. Lignan is believed to be the primary attribute for the antioxidant properties of sesame. However, information related to lignans in sesame oils are still deficient and little is known about enzymes involved in conversion of sesamin to sesamolin and from piperitol to sesamolinol. In this study, we used metabolomic (targeted LC-MS) and transcriptome (RNA-Seq) analyses to identify metabolites and key genes associated with lignan production during the young stage (YS) and matured stages (MS) of Sesame seed. The contents of 7 lignan type metabolites and expression of 83 unigenes involved in the lignan pathway differed considerably between YS and MS; 6 of metabolites were only detected at MS while no sesamol is detected in both stages. Similar to metabolite analysis output in RNA Seq analysis majority of genes in lignan biosynthesis pathway were upregulated at MS. These findings will enhance our knowledge of lignan biosynthesis in seeds and provide a foundation for molecular breeding in sesame.