Transcriptome of Paeonia ostii developing seeds revealed transcriptional factors, mRNAs and LncRNAs related to fatty acid synthesis and accumulation

Paeonia ostii seeds are an excellent source of favorable vegetable oil due to their high levels of unsaturated fatty acids, especially alpha-linolenic acid. The exploration of regulatory networks for lipid synthesis and accumulation is beneficial for increasing the lipid content and yield of P. ostii seeds. In the present study, seeds at the increasing and stable stages of fatty acid (FA) content were evaluated and sampled for comparative transcriptome analysis in P. ostii. Totally, 740 significantly differential expression genes containing 362 TFs were screened and were relevant for lipid metabolism, carbon partitioning, and energy provision for oil biosynthesis. Moreover, 26 pairs of LncRNA-mRNA associated with FA synthesis and accumulation were obtained. The expression of key genes (LTP, ADH, ACP, PDAT, FAD2, FAD3, WRI1, FUS3, LEC1, etc.) and eight putative LncRNAs were validated using qRT-PCR. Furthermore, the function and relationship of PoWRI1 and PoPDAT were determined through ectopic overexpression, dual-luciferase reporter assay, and yeast one hybrid. The results showed that the over-expression of PoWRI1 and PoPDAT promoted FA accumulation. Together, the results obtained could provide a reference for the genomic complement and studying the molecular regulatory mechanism of oil accumulation and cultivating new varieties with high oil seeds in tree peony.