Evolution of serine carboxypeptidase-like acyltransferases in the monocots

The serine carboxypeptidases are a large family of proteases. In higher plants some members of this family have diversified and adopted new functions as acyltransferases required for the synthesis of natural products. We recently reported the first serine carboxypeptidase-like (SCPL) acyltransferase enzyme to be characterised from monocotyledonous plants.1 This enzyme, AsSCPL1, is required for acylation of antimicrobial terpenes (avenacins) that are produced in the roots of oat (Avena spp.) and that provide protection against soil-borne pathogens. The SCPL enzyme family has undergone substantial expansion following the divergence of monocots and dicots. Here we discuss the evolution of the SCPL enzyme family in monocots, their contribution to metabolic diversity, and the roles of these enzymes in biotic and abiotic stress tolerance.