AUTHOR=Khan Irfan Ullah , Ali Akhtar , Khan Haris Ali , Baek Dongwon , Park Junghoon , Lim Chae Jin , Zareen Shah , Jan Masood , Lee Sang Yeol , Pardo Jose M. , Kim Woe Yeon , Yun Dae-Jin 

TITLE=PWR/HDA9/ABI4 Complex Epigenetically Regulates ABA Dependent Drought Stress Tolerance in Arabidopsis

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.00623

DOI=10.3389/fpls.2020.00623

ISSN=1664-462X

ABSTRACT=<p>Drought stress adversely affects plant growth and development and significantly reduces crop productivity and yields. The phytohormone abscisic acid (ABA) rapidly accumulates in response to drought stress and mediates the expression of stress-responsive genes that help the plant to survive dehydration. The protein Powerdress (PWR), which interacts with Histone Deacetylase 9 (HDA9), has been identified as a critical component regulating plant growth and development, flowering time, floral determinacy, and leaf senescence. However, the role and function of PWR and HDA9 in abiotic stress response had remained elusive. Here we report that a complex of PWR and HDA9 interacts with ABI4 and epigenetically regulates drought signaling in plants. T-DNA insertion mutants of <italic>PWR</italic> and <italic>HDA9</italic> are insensitive to ABA and hypersensitive to dehydration. Furthermore, the expression of ABA-responsive genes (<italic>RD29A</italic>, <italic>RD29B</italic>, and <italic>COR15A</italic>) is also downregulated in <italic>pwr</italic> and <italic>hda9</italic> mutants. Yeast two-hybrid assays showed that PWR and HDA9 interact with ABI4. Transcript levels of genes that are normally repressed by ABI4, such as <italic>CYP707A1</italic>, <italic>AOX1a</italic> and <italic>ACS4</italic>, are increased in <italic>pwr</italic>. More importantly, during dehydration stress, PWR and HDA9 regulate the acetylation status of the <italic>CYP707A1</italic>, which encodes a major enzyme of ABA catabolism. Taken together, our results indicate that PWR, in association with HDA9 and ABI4, regulates the chromatin modification of genes responsible for regulation of both the ABA-signaling and ABA-catabolism pathways in response to ABA and drought stress.</p>