Hiptage benghalensis is a vine-like plant and has been used for medicinal and ornamental purposes in India and Thailand for many years. H. benghalensis seed oil contains a high amount of ricinoleic acid and represents an emerging source of this unusual fatty acid.

Unlike the extensive studies regarding ricinoleic acid biosynthesis in castor, the mechanism of ricinoleic acid accumulation in Hiptage plants is yet to be explored. 

Researchers from Xishuangbanna Tropical Botanical Garden (XTBG) conducted a study to explore the mechanisms of ricinoleic acid biosynthesis and regulation in H. benghalensis at the transcriptional level. They got their results published in Biotechnology for Biofuels. 

The researchers harvested H. benghalensis seeds at five developing stages (13, 16, 19, 22, and 25 days after pollination) for lipid analysis. They compared the fatty acid composition of six Hiptage spp and identified that H. benghalensi was the one with the highest ricinoleic acid content in seeds. 

By a joint analysis with second-generation sequencing (SGS) and single-molecule real-time sequencing (SMRT), the researchers obtained comprehensive transcriptome profiles of H. benghalensis seeds at different developing stages. They then analyzed the expression of functional transcripts encoding enzymes associated with lipid biosynthesis. 

Bioinformatics analysis showed that ricinoleic acid accumulation may involve multiple players including transcription factors, long noncoding RNAs and various lipid-related enzymes. 

"Our study was the first step toward the understanding of the molecular mechanisms of ricinoleic acid biosynthesis and oil accumulation in H. benghalensis seeds", said Dr. TIAN Bo, the first author of the study. 

"It set a foundation for developing H. benghalensis into a novel ricinoleic acid feedstock at the transcriptomic level and provided valuable candidate genes for improving ricinoleic acid production in other plants", said TIAN.