AUTHOR=Lee Hong Gil , Jeong Yeong Yeop , Lee Hongwoo , Seo Pil Joon 

TITLE=Arabidopsis HISTONE DEACETYLASE 9 Stimulates Hypocotyl Cell Elongation by Repressing GIGANTEA Expression Under Short Day Photoperiod

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.950378

DOI=10.3389/fpls.2022.950378

ISSN=1664-462X

ABSTRACT=<p>Developmental plasticity contributes to plant adaptation and fitness in a given condition. Hypocotyl elongation is under the tight control of complex genetic networks encompassing light, circadian, and photoperiod signaling. In this study, we demonstrate that HISTONE DEACETYLASE 9 (HDA9) mediates day length-dependent hypocotyl cell elongation. HDA9 binds to the <italic>GIGANTEA</italic> (<italic>GI</italic>) locus involved in photoperiodic hypocotyl elongation. The short day (SD)-accumulated HDA9 protein promotes histone H3 deacetylation at the <italic>GI</italic> locus during the dark period, promoting hypocotyl elongation. Consistently, <italic>HDA9</italic>-deficient mutants display reduced hypocotyl length, along with an increase in <italic>GI</italic> gene expression, only under SD conditions. Taken together, our study reveals the genetic basis of day length-dependent cell elongation in plants.</p>