Systematic Analysis and Biochemical Characterization of the Caffeoyl Shikimate Esterase Gene Family in Poplar.

Caffeoyl shikimate esterase (CSE) hydrolyzes caffeoyl shikimate into caffeate and shikimate in the phenylpropanoid pathway. In this study, we performed a systematic analysis of the CSE gene family and investigated the possible roles of and -like genes in . We conducted a genome-wide analysis of the CSE gene family, including functional and phylogenetic analyses of and -like genes, using the poplar () genome. Eighteen and -like genes were identified in the genome, and five phylogenetic groups were identified from phylogenetic analysis. CSEs in Group Ia, which were proposed as bona fide CSEs, have probably been lost in most monocots except . Primary functional classification showed that and had putative function in lignin biosynthesis. In addition, , along with , might also respond to stress with a function in cell wall biosynthesis. Enzymatic assay of PoptoCSE1 (), -2 and -12 showed that PoptoCSE1 and -2 maintained CSE activity. PoptoCSE1 and 2 had similar biochemical properties, tissue expression patterns and subcellular localization. Most of the -like genes are homologs of (monoacylglycerol lipase) genes in and may function as MAG lipase in poplar. Our study provides a systematic understanding of this novel gene family and suggests the function of CSE in monolignol biosynthesis in .