Transcriptome sequencing discovers key genes involved in oil accumulation and biosynthesis of unsaturated fatty acid in seeds of Hibiseu manihot

Abstract To reveal the genes associated with fatty acid synthesis and accumulation in the seeds of Hibiseu manihot, transcriptome analysis was performed using seeds from 5, 15 and 30 days after flowering (DAF) in Hibiseu manihot. There were 3338 (1320 down, 2018 up) and 6657 (3408 down, 3249 up) differentially expressed genes in 5 DAF vs 15 DAF, 5 DAF vs 30 DAF. A total of 413 DEGs were identified that were associated with fatty acid pathway, and most of them were highly expressed at 5 DAF and 15 DAF. The expression levels of PDAT and FATA increased with development, KASII and FAD2 were highly expressed in the early and middle stages, respectively, SAD was highly expressed in the late stage, and the high expression of KASII and SAD and the low expression of FAD2 were related to the accumulation of oleic acid, while the high expression of FAD2 and the low expression of FAD3 contributed to linoleic acid accumulation. Consistent with the results of fatty acid content measurements at different stages of Hibiseu manihot, oleic acid content increased and then decreased with seed development, while linoleic acid decreased and then increased. It was hypothesised that KASII, SAD, FATA, PDAT and FAD2 might be closely related to the high oleic acid content of Hibiseu manihot seeds, which laid a molecular foundation for further study on the functions of these genes. This study has important significance and reference value for discovering the key genes involved in the fatty acid synthesis and accumulation in Hibiseu manihot.