The 90 kDa heat shock protein (HSP90) is widely involved in various developmental processes and stress responses in plants. However, the molecular chaperone HSP90-constructed protein complex and its function in cassava remain elusive. In this study, we report that HSP90 is essential for drought stress resistance in cassava by regulating abscisic acid (ABA) and hydrogen peroxide (H2 O2 ) using two specific protein inhibitors of HSP90 (geldanamycin (GDA) and radicicol (RAD)). Among 10 MeHSP90s, the transcript of MeHSP90.9 is largely induced during drought stress. Further investigation identifies MeWRKY20 and MeCatalase1 as MeHSP90.9-interacting proteins. MeHSP90.9-, MeWRKY20-, or MeCatalase1-silenced plants through virus-induced gene silencing display drought sensitivity in cassava, indicating that they are important to drought stress response. MeHSP90.9 can promote the direct transcriptional activation of MeWRKY20 on the W-box element of MeNCED5 promoter, encoding a key enzyme in ABA biosynthesis. Moreover, MeHSP90.9 positively regulates the activity of MeCatalase1, and MeHSP90.9-silenced cassava leaves accumulate more H2 O2 under drought stress. Taken together, we demonstrate that the MeHSP90.9 chaperone complex is a regulator of drought stress resistance in cassava.

中文翻译：

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伴侣 MeHSP90 招募 MeWRKY20 和 MeCatalase1 来调节木薯的抗旱性。

90 kDa 热休克蛋白 (HSP90) 广泛参与植物的各种发育过程和应激反应。然而，分子伴侣 HSP90 构建的蛋白质复合物及其在木薯中的功能仍然难以捉摸。在这项研究中，我们报告 HSP90 通过使用两种特定的 HSP90 蛋白抑制剂（格尔德霉素 (GDA) 和根赤霉素 (RAD)）调节脱落酸 (ABA) 和过氧化氢 (H2 O2 ) 对木薯的干旱胁迫抗性至关重要。在 10 个 MeHSP90 中，MeHSP90.9 的转录本主要在干旱胁迫期间被诱导。进一步的研究将 MeWRKY20 和 MeCatalase1 确定为与 MeHSP90.9 相互作用的蛋白质。MeHSP90.9-、MeWRKY20-或MeCatalase1-通过病毒诱导的基因沉默沉默的植物在木薯中表现出干旱敏感性，表明它们对干旱胁迫反应很重要。MeHSP90.9可促进MeWRKY20在MeNCED5启动子W-box元件上的直接转录激活，编码ABA生物合成中的关键酶。此外，MeHSP90.9 正向调节 MeCatalase1 的活性，MeHSP90.9 沉默的木薯叶片在干旱胁迫下积累更多的 H2O2。总之，我们证明了 MeHSP90.9 伴侣复合物是木薯抗旱性的调节剂。