Miao Yuchen, Lv Dong, Wang Pengcheng, Wang Xue-Chen, Chen Jia, Miao Chen, Song Chun-Peng
Henan Key Laboratory of Plant Stress Biology, Department of Biology, Henan University, Kaifeng 475001, China.
Plant Cell. 2006 Oct;18(10):2749-66. doi: 10.1105/tpc.106.044230. Epub 2006 Sep 22.
We isolated two T-DNA insertion mutants of Arabidopsis thaliana GLUTATHIONE PEROXIDASE3 (ATGPX3) that exhibited a higher rate of water loss under drought stress, higher sensitivity to H(2)O(2) treatment during seed germination and seedling development, and enhanced production of H(2)O(2) in guard cells. By contrast, lines engineered to overexpress ATGPX3 were less sensitive to drought stress than the wild type and displayed less transpirational water loss, which resulted in higher leaf surface temperature. The atgpx3 mutation also disrupted abscisic acid (ABA) activation of calcium channels and the expression of ABA- and stress-responsive genes. ATGPX3 physically interacted with the 2C-type protein phosphatase ABA INSENSITIVE2 (ABI2) and, to a lesser extent, with ABI1. In addition, the redox states of both ATGPX3 and ABI2 were found to be regulated by H(2)O(2). The phosphatase activity of ABI2, measured in vitro, was reduced approximately fivefold by the addition of oxidized ATGPX3. The reduced form of ABI2 was converted to the oxidized form by the addition of oxidized ATGPX3 in vitro, which might mediate ABA and oxidative signaling. These results suggest that ATGPX3 might play dual and distinctive roles in H(2)O(2) homeostasis, acting as a general scavenger and specifically relaying the H(2)O(2) signal as an oxidative signal transducer in ABA and drought stress signaling.
我们分离出了拟南芥谷胱甘肽过氧化物酶3（ATGPX3）的两个T-DNA插入突变体，它们在干旱胁迫下表现出更高的水分流失率，在种子萌发和幼苗发育过程中对H₂O₂处理更敏感，并且保卫细胞中H₂O₂的产生增加。相比之下，经基因工程改造过表达ATGPX3的株系比野生型对干旱胁迫的敏感性更低，蒸腾水分流失更少，这导致叶片表面温度更高。atgpx3突变还破坏了脱落酸（ABA）对钙通道的激活以及ABA和胁迫响应基因的表达。ATGPX3与2C型蛋白磷酸酶ABA不敏感蛋白2（ABI2）发生物理相互作用，并且在较小程度上与ABI1相互作用。此外，发现ATGPX3和ABI2的氧化还原状态均受H₂O₂调节。在体外测定时，添加氧化型ATGPX3可使ABI2的磷酸酶活性降低约五倍。在体外添加氧化型ATGPX3可将还原型ABI2转化为氧化型，这可能介导ABA和氧化信号传导。这些结果表明，ATGPX3可能在H₂O₂稳态中发挥双重且独特的作用，作为一般清除剂，并作为ABA和干旱胁迫信号传导中的氧化信号转导器特异性地传递H₂O₂信号。
