Functional analysis of a beta-ketoacyl-CoA synthase gene, MpFAE2, by gene silencing in the liverwort Marchantia polymorpha L.

We have isolated a beta-ketoacyl CoA synthase (KCS) gene, MpFAE2, from a liverwort, Marchantia polymorpha, and identified its substrate specificity using the technique of dsRNA-mediated gene silencing and overexpression. KCS catalyzes an essential reaction in the fatty acid elongation process, i.e., condensation of malonyl-CoA with acyl-CoA. By introducing a construct with a hairpin structure containing a partial MpFAE2 gene, the level of the MpFAE2 gene expression was suppressed constitutively. The transgenic plants showed a specific accumulation of fatty acid 18:0. In contrast, in transgenic M. polymorpha plants overexpressing the MpFAE2 gene, fatty acid 22:0 is accumulated. These results indicate that the MpFAE2 gene product catalyzes the elongation steps of 18:0 to 20:0 and possibly also of 20:0 to 22:0.