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Summary: Drought stress causes substantial losses in crop production per year worldwide, threatening global food security. Identification of the genetic components underlying drought tolerance in plants is of great importance. In this study, we report that loss‐of‐function of the chromatin‐remodeling factor PICKLE (PKL), which is involved in repression of transcription, enhances drought tolerance of Arabidopsis.At first, we find that PKL interacts with ABI5 to regulate seed germination, but PKL regulates drought tolerance independently of ABI5. Then, we find that PKL is necessary for repressing the drought‐tolerant gene AFL1, which is responsible for the drought‐tolerant phenotype of pkl mutant. Genetic complementation tests demonstrate that the Chromo domain and ATPase domain but not the PHD domain are required for the function of PKL in regulating drought tolerance. Interestingly, we find that the DNA‐binding domain (DBD) is essential for the protein stability of PKL.Furthermore, we demonstrate that the SUMO E3 ligase MMS21 interacts with and enhances the protein stability of PKL. Genetic interaction analysis shows that MMS21 and PKL additively regulate plant drought tolerance.Collectively, our findings uncover a MMS21‐PKL‐AFL1 module in regulating plant drought tolerance and offer insights into a novel strategy to improve crop drought tolerance. [ABSTRACT FROM AUTHOR]

Summary: The juvenile‐to‐adult vegetative phase change in flowering plants is mediated by a decrease in miR156 levels. Downregulation of MIR156A/MIR156C, the two major sources of miR156, is accompanied by a decrease in acetylation of histone 3 lysine 27 (H3K27ac) and an increase in trimethylation of H3K27 (H3K27me3) at MIR156A/MIR156C in Arabidopsis.Here, we show that histone deacetylase 9 (HDA9) is recruited to MIR156A/MIR156C during the juvenile phase and associates with the CHD3 chromatin remodeler PICKLE (PKL) to erase H3K27ac at MIR156A/MIR156C.H2Aub and H3K27me3 become enriched at MIR156A/MIR156C, and the recruitment of Polycomb Repressive Complex 2 (PRC2) to MIR156A/MIR156C is partially dependent on the activities of PKL and HDA9.Our results suggest that PKL associates with histone deacetylases to erase H3K27ac and promote PRC1 and PRC2 activities to mediate vegetative phase change and maintain plants in the adult phase after the phase transition. [ABSTRACT FROM AUTHOR]