Laboratory of Plant Stress Biology, Department of Biology, Henan University, Kaifeng 475001, China.
Plant Cell. 2010 Sep;22(9):2981-98. doi: 10.1105/tpc.109.072959. Epub 2010 Sep 24.
Nitric oxide (NO) is a bioactive molecule that functions in numerous physiological and developmental processes in plants, including lateral root development. In this study, we used biochemical and genetic approaches to analyze the function of Arabidopsis thaliana mitogen-activated protein kinase 6 (MPK6) in the regulation of NO synthesis in response to hydrogen peroxide (H₂O₂) during lateral root development. In both mpk6 mutants studied, H₂O₂-induced NO synthesis and nitrate reductase (NR) activity were decreased dramatically. Furthermore, one NR isoform, NIA2, was required for the MPK6-mediated production of NO induced by H₂O₂. Notably, NIA2 interacted physically with MPK6 in vitro and in vivo and also served as a substrate of MPK6. Phosphorylation of NIA2 by MPK6 led to an increase in NR activity, and Ser-627 was identified as the putative phosphorylation site on NIA2. Phenotypical analysis revealed that mpk6-2 and mpk6-3 seedlings produce more and longer lateral roots than wild-type plants did after application of the NO donor sodium nitroprusside or H₂O₂. These data support strongly a function of MPK6 in modulating NO production and signal transduction in response to H₂O₂ during Arabidopsis root development.
一氧化氮（NO）是一种生物活性分子，在植物的许多生理和发育过程中发挥作用，包括侧根发育。在这项研究中，我们使用生化和遗传方法分析了拟南芥丝裂原活化蛋白激酶 6（MPK6）在过氧化氢（H₂O₂）诱导的侧根发育过程中调节 NO 合成中的功能。在所研究的两种 mpk6 突变体中，H₂O₂诱导的 NO 合成和硝酸还原酶（NR）活性显著降低。此外，一种 NR 同工型 NIA2 是 H₂O₂诱导的 NO 产生所必需的，该过程受 MPK6 介导。NIA2 在体外和体内与 MPK6 物理相互作用，并且也是 MPK6 的底物。MPK6 对 NIA2 的磷酸化导致 NR 活性增加，并且鉴定出丝氨酸-627 是 NIA2 上的假定磷酸化位点。表型分析表明，mpk6-2 和 mpk6-3 幼苗在应用一氧化氮供体硝普钠或 H₂O₂后产生的侧根比野生型植物更多、更长。这些数据强烈支持 MPK6 在调节拟南芥根发育过程中 H₂O₂ 应答时的 NO 产生和信号转导中的功能。
