Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, 510275, Guangzhou, PR China.
Plant Sci. 2012 Jun;188-189:10-8. doi: 10.1016/j.plantsci.2012.02.005. Epub 2012 Feb 16.
The mitogen-activated protein kinase (MAPK) phosphatases (MKPs) are important negative regulators in the MAPK signaling pathways, which play crucial roles in plant growth, regulation of development and response to environment stresses. Several MAPKs have been reported to be involved in the drought stress response, however, there is no evidence for the specific function of MKPs in drought stress. Here, a putative MKP in rice (Oryza sativa), OsIBR5, was characterized. Expression of OsIBR5 was induced by PEG6000, abscisic acid (ABA) and hydrogen peroxide (H(2)O(2)). Overexpression of OsIBR5 in tobacco plants resulted in hypersensitivity to drought and H(2)O(2) treatments. Drought and ABA-induced stomatal closure was significantly reduced in OsIBR5-overexpressing tobacco plants compared with controls. Moreover, OsIBR5 was found to interact with tobacco MAPKs SIPK and WIPK, and drought-induced WIPK activity was impaired in OsIBR5-overexpressing tobacco plants. These results indicated that OsIBR5 is a MKP which was induced by abiotic stresses and decreased tolerance to drought stress in transgenic tobacco plants.
丝裂原活化蛋白激酶（MAPK）磷酸酶（MKPs）是 MAPK 信号通路中的重要负调控因子，在植物生长、发育调控和应对环境胁迫中起着至关重要的作用。已经有报道称几种 MAPK 参与了干旱胁迫反应，但 MKP 在干旱胁迫中的特定功能尚无证据。在这里，我们对水稻（Oryza sativa）中的一个假定的 MKP，OsIBR5 进行了表征。PEG6000、脱落酸（ABA）和过氧化氢（H2O2）诱导 OsIBR5 的表达。烟草植物中 OsIBR5 的过表达导致对干旱和 H2O2 处理的超敏反应。与对照相比，OsIBR5 过表达烟草植物中的干旱和 ABA 诱导的气孔关闭显著减少。此外，发现 OsIBR5 与烟草 MAPKs SIPK 和 WIPK 相互作用，并且在 OsIBR5 过表达烟草植物中，干旱诱导的 WIPK 活性受损。这些结果表明，OsIBR5 是一种 MKP，它被非生物胁迫诱导，并降低了转基因烟草植物对干旱胁迫的耐受性。
