Waxes, Cutin, and Suberin

Abstract

Plant waxes consisting of very long-chain, relatively nonpolar lipid molecules are associated primarily with the cuticle which extends in a continuous sheet exterior to the walls of the epidermal cells of aerial tissues. In underground tissues, stems undergoing secondary growth, and wound healing sites, waxes are associated with the suberin matrix, a polymer related to cutin which has in addition to an aliphatic domain also an aromatic one. Elongases are enzyme complexes which repetitively condense short activated carbon chains to an activated primer and prepare the growing chain for the next addition. Mutations in genes whose products function in elongation can potentially be recognized by an increase in the amount of shorter homologs. The carbon chains produced by the coordinated action of elongases normally serve as substrates for associated pathways, thereby generating the diverse range of lipid classes occurring in waxes, cutin, and suberin.