Functional Characterization of a Hydroxyacid/Alcohol Hydroxycinnamoyl Transferase Produced by the Liverwort Marchantia emarginata.

The aerial organs of most terrestrial plants are covered by a hydrophobic protective cuticle. The main constituent of the cuticle is the lipid polyester cutin, which is composed of aliphatic and aromatic domains. The aliphatic component is a polyester between fatty acid/alcohol and hydroxycinnamoyl acid. The BAHD/HxxxD family enzymes are central to the synthesis of these polyesters. The nature of this class of enzymes in bryophytes has not been explored to date. Here, a gene encoding a fatty ω-hydroxyacid/fatty alcohol hydroxycinnamoyl transferase (HFT) has been isolated from the liverwort and has been functionally characterized. Experiments based on recombinant protein showed that the enzyme uses ω-hydroxy fatty acids or primary alcohols as its acyl acceptor and various hydroxycinnamoyl-CoAs-preferentially feruloyl-CoA and caffeoyl-CoA-as acyl donors at least in vitro. The transient expression of a fusion transgene in the leaf demonstrated that MeHFT is directed to the cytoplasm, suggesting that the feruloylation of cutin monomers takes place there.