Focus on putative serine carboxypeptidase-like acyltransferases in grapevine

Grapevine (Vitis vinifera L.) berry synthesizes and accumulates a large array of phenolic compounds (e.g. flavonoids and hydroxycinnamic acid derivatives), some of which result from acylation mechanisms. In grapevine, the genes encoding enzymes responsible for such acylation are largely unknown. Enzymes classified as serine carboxypeptidases (SCPs), able to transfer acyl moieties from a glucose ester, have previously been characterized in plants, and named serine carboxypeptidase-like acyltransferases (SCL-ATs). We performed genome-wide identification of SCP sequences in V. vinifera. Phylogenetic analysis revealed that only 12 grapevine SCPs, grouped in clade IA with previously characterized SCPL-AT could have an acylation function. Interestingly, seven putative SCP-ATs are grouped in a 400 kb cluster in chromosome 3. The expression level of putative SCPL-ATs has been evaluated at key stages of grape berry development in the main tissues and compared with the content of acylated phenolic compounds in the corresponding samples. The expression levels of VvGAT1 and VvGAT2 and that of VvSCP5 were increased in hairy-roots overexpressing transcription factors inducing the biosynthesis of proanthocyanidins and anthocyanins, respectively. These findings open the way for the functional characterization of the identified putative SCPL-AT from grapevine.