Mutation in barley ERA1 (Enhanced Response to ABA1) gene confers better photosynthesis efficiency in response to drought as revealed by transcriptomic and physiological analysis

Farnesylation is a post-translational modification that promotes the interaction between the modified signaling protein and membrane lipids and/or other proteins. Farnesyltransferase is the crucial enzyme involved in this process. Strikingly, plant mutants in the ERA1 (Enhanced response to ABA1) gene, encoding beta-subunit of farnesyltransferase, exhibited ABA-hypersensitivity during seed germination and drought tolerance in several species including Arabidopsis, wheat and soybean. However, the mechanism of ERA1 action has not been resolved yet. Here, we present the potential regulatory role of ERA1 in the drought signaling network in barley. With the aim of decoding the role of the ERA1 gene, we developed a unique barley mutant using TILLING analysis. Mutation in HvERA1 confers semi-dwarf phenotype, ABA-sensitivity during seed germination and drought tolerance. Our transcriptomic analysis suggested a role of HvERA1 in regulation of the crosstalk between ABA and ethylene at the onset of drought. Furthermore, analysis of hvera1.b response to prolonged drought stress linked HvERA1 to the metabolism of galactolipids, that build the chloroplast membranes. It might results in the protection of hvera1.b photosystem and thus, in its better photosynthesis performance under water stress. Together, these results indicate the possible mechanism of the primary cause of the observed alterations in the hvera1.b mutant.