Table_1_Arabidopsis HISTONE DEACETYLASE 9 Stimulates Hypocotyl Cell Elongation by Repressing GIGANTEA Expression Under Short Day Photoperiod.XLSX

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 GIGANTEA (GI) locus involved in photoperiodic hypocotyl elongation. The short day (SD)-accumulated HDA9 protein promotes histone H3 deacetylation at the GI locus during the dark period, promoting hypocotyl elongation. Consistently, HDA9-deficient mutants display reduced hypocotyl length, along with an increase in GI gene expression, only under SD conditions. Taken together, our study reveals the genetic basis of day length-dependent cell elongation in plants.

发育可塑性（Developmental plasticity）有助于植物在特定环境下的适应性与适合度。下胚轴（hypocotyl）伸长受到涵盖光信号、昼夜节律信号与光周期信号通路的复杂遗传网络的严格调控。本研究表明，组蛋白去乙酰化酶9（HDA9）可介导依赖日照长度的下胚轴细胞伸长。HDA9可结合参与光周期调控下胚轴伸长的GIGANTEA（GI）基因位点。在短日照（SD）条件下积累的HDA9蛋白可在黑暗阶段促进GI基因位点处的组蛋白H3去乙酰化修饰，进而促进下胚轴伸长。与之相符的是，仅在短日照条件下，HDA9功能缺失突变体的下胚轴长度会缩短，同时GI基因的表达量会升高。综上，本研究揭示了植物依赖日照长度的细胞伸长的遗传基础。