背景回顾：Glutaredoxins (GRXs) are essential for reactive oxygen species (ROS) homeostasis in responses of plants to environment changes. We previously identified several drought-responsive CC-type GRXs in cassava, an important tropical crop. 

提出问题：However, how CC-type GRX regulates ROS homeostasis of cassava under drought stress remained largely unknown. 

主要发现：Here, we report that a drought-responsive CC-type GRX, namely MeGRXC3, was associated with activity of catalase in the leaves of 100 cultivars (or unique unnamed genotypes) of cassava under drought stress. 

结果1-GRXC3基因功能：MeGRXC3 negatively regulated drought tolerance by modulating drought- and ABA- induced stomatal closure in transgenic cassava. It antagonistically regulated hydrogen peroxide (H2O2) accumulation in epidermal cells and guard cells. 

结果2-GRXC3翻译后调控过氧化氢酶：Moreover, MeGRXC3 interacted with two catalases of cassava, MeCAT1 and MeCAT2, and regulated their activity in vivo.  

结果3-GRXC3转录调控过氧化氢酶：Additionally, MeGRXC3 interacts with a cassava TGA transcription factor, MeTGA2, in the nucleus, and regulates the expression of MeCAT7 through a MeTGA2-MeMYB63 pathway.

结论：Overall, we demonstrated the roles of MeGRXC3 in regulating activity of catalase at both transcriptional and post-translational levels, therefore involving in ROS homeostasis and stomatal movement in responses of cassava to drought stress. Our study provides the first insights into how MeGRXC3 may be used in molecular breeding of cassava crops.

 摘 要 

谷氧还蛋白GRXs对于植物响应于环境变化后的活性氧内稳态至关重要。作者在先前对于热带作物木薯的研究中，鉴定到了几个响应干旱的CC-type GRXs。但是，这些CC-type GRX如何在干旱胁迫后调控木薯中的ROS稳态还不清楚。本文中，作者基于100个栽培种木薯干旱胁迫后的叶片为材料，发现了一个响应干旱的CC-type GRX蛋白MeGRXC3与过氧化氢酶的活性有关。MeGRXC3基因通过调节干旱和ABA诱导的气孔闭合，负调控木薯的干旱耐受性。其拮抗调控表皮细胞和保卫细胞中的过氧化氢积累。此外，MeGRXC3与木薯中的2个过氧化氢酶MeCAT1和MeCAT2互作，并调控这两个过氧化氢酶的活性。另外，MeGRXC3还会与一个木薯TGA转录因子MeTGA2在核中互作，并通过MeTGA2-MeMYB63途径调控MeCAT7基因的表达。综上，本文的研究揭示了MeGRXC3基因转录和翻译后两个水平上调控过氧化氢酶活性的重要作用，从而参与木薯响应于干旱胁迫后的ROS内稳态和气孔运动。本文的研究为如何将MeGRXC3应用于木薯的分子育种提供了初步的见解。

 阮孟斌