Chromatin remodeling complex HDA9-PWR-ABI4 epigenetically regulates drought stress response in plants

Among all the major environmental challenges, drought stress causes considerable damage to plant growth and agricultural productivity. Drought stress directly promotes the accumulation of abscisic acid (ABA) via the activation of genes that encode enzymes involved in ABA biosynthesis, which protect the plant against water-limiting conditions. At the same time, the expression of genes that encode ABA-hydroxylases that inactivate the newly synthesized ABA, is repressed by drought stress. These phenomena occur through epigenetic modifications via the reversible processes of histone acetylation and deacetylation, also known as chromatin remodeling, which is an important regulatory mechanism that responds to various environmental stresses. Recently, we had reported that the chromatin remodeling complex HDA9-PWR-ABI4 promotes the development of drought tolerance through the deacetylation of CYP707A1/2 genes that encode the major enzymes involved in ABA catabolism. Here, we discuss the role of HDA9 and PWR in regulating drought stress by modulating the acetylation status of the CYP707A genes.