Integrated analysis reveals functional genes and regulators associated with fatty acid biosynthesis in Elaeagnus...

Elaeagnus mollis Diels. is a newly developed oil plant in China, which harbors high fatty acid (FA) in its kernel oil. Functional genes and regulators associated with FA biosynthesis are widely characterized in oil crops, but it still remains elusive in E. mollis. In this study, the FA and carbohydrate content, functional genes and metabolites involved in FA biosynthesis, and the potential regulator were investigated. Results demonstrated that FA and carbohydrate contents fluctuated accompanied with kernel development and reached relatively stable status at mature stage, indicating lipid and carbohydrate metabolism orchestrated for FA biosynthesis. Unsaturated FA (85.80-465.86 mg/g) occupied ∼90% of total FA (97.97-507.07 mg/g), oleic acid (OA) and linoleic acid (LA) were two major components. We identified 436 and 2735 genes involved in lipid and carbohydrate metabolism, while 178 genes directly in FA biosynthesis. Weighted gene co-expression analysis elucidated the turquoise module illustrated significant association with OA and LA content, respectively. Co-expression analysis revealed EmWRI1 was a vital regulator in E. mollis FA biosynthesis, which was proved by transgenic of EmWRI1 in Arabidopsis. Furthermore, RNA-Seq and yeast one-hybrid assay revealed the direct interaction between EmWRI1 and proEmBCCP2. This study deciphers the FA biosynthetic regulatory mechanism in E. mollis and sets a solid foundation for genetic breeding of this newly developed oil crops.