Fatty acid accumulation analysis based on transcriptome sequencing of developmental herbaceous peony ‘Hangshao’ ( Paeonia lactiflora ‘Hangshao’) seeds

Abstract

Background: Paeonia lactiflora ‘Hangshao’ is widely cultivated in China because its root can be used to produce raw materials for traditional Chinese medicine ‘Radix Paeoniae Alba’. Due to the presence of abundant unsaturated fatty acids in its seed, it also can be regarded as a new oil plant. However, the process of the biosynthesis of unsaturated fatty acid in herbaceous peony ‘Hangshao’ remained largely unknown. Therefore, transcriptome analysis is helpful to better understand the molecular mechanisms. Results: Five main fatty acids, stearic acid, palmitic acid, oleic acid, linoleic acid and α-linolenic acid, were detected, and their absolute contents increased first and then decreased during seed development. A total of 150,156 Unigenes were obtained by transcriptome sequencing, with an average length of 1,030 bp. There were 1,550 Unigenes annotated in the seven functional databases including NR, NT, GO, KOG, KEGG, SwissProt and InterPro. Based on KEGG database, 1,766 Unigenes were annotated in the lipid metabolic pathways, among which 103, 74 and 70 Unigenes are annotated into fatty acid biosynthesis pathway, fatty acid elongation pathway and unsaturated fatty acid synthesis pathway; respectively. A total of 1480 DEGs were detected. Among them, 83 DEGs were enriched in the fatty acid metabolism pathway, including 12 DEGs involved in the fatty acid biosynthesis and 1 DEG involved in fatty acid elongation. Furthermore, qRT-PCR was used to analyze the expression patterns of nine fatty acid biosynthetic related genes including FBCP, BC, FabD, FabF, FATB, KCR, FAD2, FAD3 and FAD7, and it showed that they all highest expressed at 45 DAF. Conclusions: This study provides the first comprehensive genomic resources characterizing herbaceous peony seeds gene expression at the transcriptional level. These data lay the foundation for elucidating the molecular mechanism of the lipid biosynthesis and fatty acid accumulation for herbaceous peony 'Hangshao'.