Unravelling a stearidonic acid-rich triacylglycerol biosynthetic pathway in the developing seeds of Buglossoides...

Buglossoides arvensis is an emerging oilseed crop that is rich in stearidonic acid (SDA) and has several potential applications in human health and nutrition. The molecular basis of SDA biosynthesis in this plant remains unknown due to lack of genomic information. To unravel key genes involved in SDA-rich triacylglycerol (TAG) biosynthesis, we performed transcriptome sequencing of pooled mRNA from five different developmental stages of B. arvensis seeds using Illumina NextSeq platform. De novo transcriptome assembly generated 102,888 clustered transcripts from 39.83 million high-quality reads. Of these, 62.1% and 55.54% of transcripts were functionally annotated using Uniprot-Viridiplantae and KOG databases, respectively. A total of 10,021 SSR-containing sequences were identified using the MISA tool. Deep mining of transcriptome assembly using in silico tools led to the identification of genes involved in fatty acid and TAG biosynthesis. Expression profiling of 17 key transcripts involved in fatty acid desaturation and TAG biosynthesis showed expression patterns specific to the development stage that positively correlated with polyunsaturated fatty acid accumulation in the developing seeds. This first comprehensive transcriptome analysis provides the basis for future research on understanding molecular mechanisms of SDA-rich TAG accumulation in B. arvensis and aids in biotechnological production of SDA in other oilseed crops.