HDA6 Controls Cytoskeleton Organization and Cell Polarity in Arabidopsis Leaf Epidermal Cells through Regulation of ROP6 Expression

The transcriptional regulation of Rho-related GTPase from plants (ROPs) which determine cell polarity formation and maintenance during plant development remains an area warranting further investigation. In this study, we elucidated the epigenetic mechanism of histone deacetylase HDA6 in transcriptional repression of ROP6 and its impact on cell polarity and morphogenesis in Arabidopsis leaf epidermal pavement cells. We found that the hda6 mutant axe1-4 exhibited impaired jigsaw-shaped pavement cells and convoluted leaves. This correlated with disruptions in the spatial organizations of cortical microtubules and actin filaments, which is integral to pavement cell indentation and lobe formation. Further transcriptional analyses and chromatin immunoprecipitation assay revealed that HDA6 specifically represses ROP6 expression through histone H3K9K14 deacetylation. Importantly, overexpression of dominant negative-rop6 in axe1-4 restored interdigitated cell morphology. Our study highlights HDA6 as a key regulator in Arabidopsis pavement cell morphogenesis through epigenetic suppression of ROP6, crucial for cytoskeletal arrangements and cell polarity.