Zhang Haidao, Guo Fu, Qi Peipei, Huang Yizi, Xie Yongyao, Xu Lei, Han Ning, Xu Lin, Bian Hongwu
Institute of Genetic and Regenerative Biology, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou 510642, China.
Plant Cell Physiol. 2020 Sep 1;61(9):1646-1660. doi: 10.1093/pcp/pcaa086.
Histone deacetylases (HDACs) play important roles in the regulation of eukaryotic gene expression. The role of HDACs in specialized transcriptional regulation and biological processes is poorly understood. In this study, we evaluated the global expression patterns of genes related to epigenetic modifications during callus initiation in rice. We found that the repression of HDAC activity by trichostatin A (TSA) or by OsHDA710 mutation (hda710) results in impaired callus formation of rice mature embryo and increased global histone H3 acetylation levels. The HDAC inhibition decreased auxin response and cell proliferation in callus formation. Meanwhile, the transcriptional repressors OsARF18 and OsARF22 were upregulated in the callus of hda710. The chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) analysis demonstrated that the callus of hda710 exhibited enhanced histone H3 acetylation levels at the chromatin regions of OsARF18 and OsARF22. Furthermore, we found that OsARF18 and OsARF22 were regulated through OsHDA710 recruitment to their target loci. In addition, overexpression of OsARF18 decreased the transcription of downstream genes PLT1 and PLT2 and inhibited callus formation of the mature embryo. These results demonstrate that OsHDA710 regulates callus formation by suppressing repressive OsARFs via histone deacetylation during callus formation of rice mature embryo. This indicates that OsHDA710-mediated histone deacetylation is an epigenetic regulation pathway for maintaining auxin response during cell dedifferentiation.
组蛋白去乙酰化酶（HDACs）在真核基因表达调控中发挥着重要作用。HDACs在特殊转录调控和生物学过程中的作用尚不清楚。在本研究中，我们评估了水稻愈伤组织诱导过程中与表观遗传修饰相关基因的整体表达模式。我们发现，曲古抑菌素A（TSA）或OsHDA710突变（hda710）对HDAC活性的抑制导致水稻成熟胚愈伤组织形成受损，且整体组蛋白H3乙酰化水平升高。HDAC抑制降低了愈伤组织形成过程中的生长素反应和细胞增殖。同时，转录抑制因子OsARF18和OsARF22在hda710愈伤组织中上调。染色质免疫沉淀定量PCR（ChIP-qPCR）分析表明，hda710愈伤组织在OsARF18和OsARF22的染色质区域表现出增强的组蛋白H3乙酰化水平。此外，我们发现OsARF18和OsARF22是通过OsHDA710募集到其靶位点进行调控的。另外，OsARF18的过表达降低了下游基因PLT1和PLT2的转录，并抑制了成熟胚愈伤组织的形成。这些结果表明，在水稻成熟胚愈伤组织形成过程中，OsHDA710通过组蛋白去乙酰化抑制抑制性OsARFs来调控愈伤组织形成。这表明OsHDA710介导的组蛋白去乙酰化是细胞去分化过程中维持生长素反应的一种表观遗传调控途径。
