DataSheet_3_HD2A and HD2C co-regulate drought stress response by modulating stomatal closure and root growth in Arabidopsis.docx

Histone deacetylase 2 (HD2) is a unique family of histone deacetylases (HDACs) in plants. Despite evidence that certain HD2 family HDACs play an important role in plant growth and stress response, the coordination of HD2s in these processes remains largely unknown. We found that HD2-type, HD2A and HD2C coordinate to play a role in drought stress response in Arabidopsis. We showed that the hd2a.hd2c double mutant (Mac16) exhibit decreased drought survival and increased water loss as compared to the single mutants, hd2a and hd2c. Gene expression analysis showed that the ABI1 and ABI2 genes were upregulated and SLAC1 was downregulated which led to the modified stomatal functioning in the Mac16 as compared to the single mutants. Overexpression of HD2A and HD2C showed enhanced drought survival and decreased water loss. We also showed that the GA2ox1 and GA2ox2 genes, which are involved in the catabolism of bioactive gibberellic acids, were upregulated in the Mac16 as compared to the single mutants, which led to a decreased root growth in the Mac16. Furthermore, we showed that HD2A and HD2C can physically interact and increased genome-wide H3K9 acetylation was observed in the Mac16, compared to the single mutants. Overall, our investigation revealed that HD2A and HD2C coordinate to play a cumulative role in drought stress response and root growth in Arabidopsis.

组蛋白去乙酰化酶2（Histone deacetylase 2, HD2）是植物中一类独特的组蛋白去乙酰化酶（histone deacetylases, HDACs）家族。尽管已有研究证实部分HD2家族成员在植物生长与胁迫响应中发挥关键作用，但HD2家族成员在上述生物学过程中的协同调控机制仍尚未完全明晰。我们发现，HD2亚型HD2A与HD2C在拟南芥的干旱胁迫应答过程中存在协同功能。实验结果显示，相较于单突变体hd2a和hd2c，hd2a.hd2c双突变体（Mac16）的干旱存活率显著降低，水分流失量明显升高。基因表达分析表明，与单突变体相比，Mac16中ABI1与ABI2基因表达上调，SLAC1基因表达下调，进而改变了其气孔调控功能。过表达HD2A与HD2C可增强拟南芥的干旱存活率，并减少水分流失。我们还发现，相较于单突变体，Mac16中参与生物活性赤霉素分解代谢的GA2ox1与GA2ox2基因表达上调，导致该双突变体的根系生长受到抑制。进一步实验证实，HD2A与HD2C可发生物理互作；且相较于单突变体，Mac16全基因组范围内的组蛋白H3赖氨酸9乙酰化水平显著升高。综上，本研究揭示HD2A与HD2C协同发挥累积效应，共同参与拟南芥的干旱胁迫应答与根系生长调控过程。