Wei Yunxie, Liu Wen, Hu Wei, Yan Yu, Shi Haitao
Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, College of Tropical Crops, Hainan University, Haikou, Hainan, 570228, China.
Key Laboratory of Three Gorges Regional Plant Genetics & Germplasm Enhancement (CTGU)/ Biotechnology Research Center, College of Biological and Pharmaceutical Sciences, China Three Gorges University, Yichang, Hubei, 443002, China.
New Phytol. 2020 Apr;226(2):476-491. doi: 10.1111/nph.16346. Epub 2020 Jan 2.
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 (H O ) 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 H O under drought stress. Taken together, we demonstrate that the MeHSP90.9 chaperone complex is a regulator of drought stress resistance in cassava.
90千道尔顿热休克蛋白（HSP90）广泛参与植物的各种发育过程和应激反应。然而，由分子伴侣HSP90构建的蛋白复合物及其在木薯中的功能仍不清楚。在本研究中，我们报告HSP90通过使用HSP90的两种特异性蛋白抑制剂（格尔德霉素（GDA）和雷迪西醇（RAD））调节脱落酸（ABA）和过氧化氢（H₂O₂），对木薯的抗旱性至关重要。在10个木薯热休克蛋白基因（MeHSP90s）中，MeHSP90.9的转录本在干旱胁迫期间大量被诱导。进一步研究确定MeWRKY20和Me过氧化氢酶1（MeCatalase1）为与MeHSP90.9相互作用的蛋白。通过病毒诱导基因沉默使MeHSP90.9、MeWRKY20或MeCatalase1沉默的木薯植株表现出干旱敏感性，表明它们对干旱胁迫反应很重要。MeHSP90.9可以促进MeWRKY20对MeNCED5启动子的W盒元件的直接转录激活，MeNCED5是ABA生物合成中的关键酶。此外，MeHSP90.9正向调节MeCatalase1的活性，并且在干旱胁迫下，MeHSP90.9沉默的木薯叶片积累更多的H₂O₂。综上所述，我们证明MeHSP90.9伴侣复合物是木薯抗旱性的调节因子。
