Integrated transcriptome and fatty acid profiling provide the insights into lipid metabolism during seed development of Acer truncatum

Owing to its numerous physiological effects, Acer truncatum seed oil (ATO) is increasingly popular as a novel source of edible oil in China. To explore the characteristics of ATO accumulation, the potential biosynthetic mechanisms of the main fatty acids (FAs) were investigated during the six different developmental stages of A. truncatum seeds (i.e., S1 - S6). The results indicated that the ATO yields significantly increased from S1 to S5, and then decreased (S6), whereby the ratio of unsaturated fatty acids reached up to 82.63–90.65% of the total ATO content. The highest content of nervonic acid was observed at S6. Dynamic transcriptome data analyses revealed that 38,932 genes were actively transcribed in the five seed developmental stages (i.e., S1-S5), 103 of which were related to lipid metabolism. Combining with the gene expression and FA profiling, the potential metabolism of the main FA was further explored. Notably, changes in C18:1-CoA transformation were observed at the later periods of A. truncatum seed development (especially from S4 to S5), which might be the key factor limiting the accumulation of very long-chain fatty acids (VLCFAs). Additionally, 24 key functional genes related to lipid metabolism were highly correlated with VLCFA biosynthesis. Finally, 11 potential transcription factors from the bHLH, GRAS, bZIP, AP2/ERF, and MADS families exhibited highly positive correlations with these key functional genes in lipid metabolism, all of which might play important roles in regulating of VLCFA accumulation.