Genome-wide binding site analysis of MaASR reveals its crucial roles in multiple drought stress response pathways

Abscisic acid (ABA)-, stress-, and ripening-induced (ASR) proteins are involved in abiotic stress responses. However, the exact molecular mechanism underlying their function remains unclear. Notably, the direct targets of ASRs that confer drought stress tolerance have not yet been identified.In this study, we report that MaASR expression was induced by drought stress and MaASR overexpression in Arabidopsis strongly enhanced drought stress tolerance. Physiological analyses indicated that transgenic lines had higher survival rates, germination rates and proline content, and lower water loss rates (WLR) and malondialdehyde (MDA) content. MaASR-overexpressing lines also showed smaller leaves and reduced sensitivity to ABA. Further, microarray and chromatin immunoprecipitation-based sequencing (ChIP-seq) analysis revealed that MaASR participates in regulating photosynthesis, respiration, carbohydrate and phytohormone metabolism and signal transduction to confer plants with enhanced drought stress tolerance. Direct interactions of MaASR with promoters for the hexose transporter and Rho GTPase-activating protein (RhoGAP) genes were confirmed by electrophoresis mobility shift array (EMSA) analysis. Our results indicate that MaASR acts as a crucial regulator of photosynthesis, respiration, carbohydrate and phytohormone metabolism and signal transduction to mediate drought stress tolerance. Total RNA of arabidopsis was extracted using the TRIZOL Reagent according to the manufacturer's instructions. Gene-expression profiling was performed for each pooling RNA sample separately on the GeneChip_ Porcine Genome Array (Affymetrix) at CapitalBio Corporation (Beijing, China) in which GeneChip microarray service was certificated by Affymetrix.