Phylogenomic Analyses of 1-Aminocyclopropane-1-Carboxylate Synthase Genes and Their Role in Phenotypic Plasticity to Drought Stress

Ethylene, among other hormones, plays a major role in controlling phenotypic plasticity of plant in different habitats. The 1-aminocyclopropane-1-carboxylate (ACC) synthase is a key enzyme involved in ethylene biosynthesis by converting S-adenosyl methionine (SAM) to ACC, which is then oxidized to ethylene. As such, ACC synthase proteins are involved in plant response to various environmental cues and play a major role in plant adaptation. It was suggested that differential expression of ACC synthase genes might underlay phenotypic plasticity to photoperiod, temperature, and drought stress. Here, we performed a phylogenomic study of ACC synthase genes using an extended set of sequences from various land plants. We showed that ACC synthase genes were distributed in three classes including sequences from monocots, eudicots, basal angiosperms and moss. We also analyzed the evolution and the expression profiles of ACC synthase genes following drought stress in two Boechera stricta genotypes with varying level of phenotypic plasticity to drought stress. Results from this work will be reported.