Transcriptomic analysis of high oil-yielding cultivated white sesame and low oil-yielding wild black sesame seeds reveal differentially expressed genes for oil and seed coat colour

Sesame is a well-known and primordial oilseed crop. The commonly cultivated Indian sesame (S. indicum) seed accumulates more than 50% oil and is pale yellow in colour at maturity. On the contrary, wild S. mulayanum is a low oil-containing (<50%) genotype, with brownish black seed coat colour. The genic foundation of sesame oil quantity, quality and seed coat colour remains poorly known due to its intricacy. The present study examines the transcriptome of developing seeds from two sesame types, S. indicum and S. mulayanum, and sheds insight on the genes involved in oil biosynthesis and seed coat colour. We have carried out RNA sequencing of developing seeds at 10 and 30 DAP (days after pollination) from two genotypes and performed differential expression study. The high oil containing cultivated sesame revealed high expression of the key lipid biosynthesis genes like acetyl-CoA carboxylase, glycerol-3-phosphate acyltransferase, choline phospho transferase, GDSL esterase or lipase, lipid transfer protein, and carboxylesterase. Furthermore, many transcription factors were differentially expressed during seed maturation, including bHLH30, PIF1, ASIL2, and WRKY. The genes controlling seed coat colour included polyphenol oxidases, NAC domain-containing protein 43, and pentatricopeptide repeat-containing proteins. Several transcription factors controlling anthocyanin biosynthesis, such as GATA 18-like90, zinc finger protein, WRKY, PIF1, and ASIL2 showed significant alterations in their expression levels. This study generated a considerable transcriptome dataset and gene list controlling oil production and seed coat colour modulation in sesame, which we envisage to validate through functional studies.