An Zhenfeng, Jing Wen, Liu Youliang, Zhang Wenhua
College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, PR China.
J Exp Bot. 2008;59(4):815-25. doi: 10.1093/jxb/erm370. Epub 2008 Feb 13.
H(2)O(2) is an essential signal in absicic acid (ABA)-induced stomatal closure. It can be synthesized by several enzymes in plants. In this study, the roles of copper amine oxidase (CuAO) in H(2)O(2) production and stomatal closure were investigated. Exogenous ABA stimulated apoplast CuAO activity, increased H(2)O(2) production and Ca(2+) levels in Vicia faba guard cells, and induced stomatal closure. These processes were impaired by CuAO inhibitor(s). In the metabolized products of CuAO, only H(2)O(2) could induce stomatal closure. By the analysis of enzyme kinetics and polyamine contents in leaves, putrescine was regarded as a substrate of CuAO. Putrescine showed similar effects with ABA on the regulation of H(2)O(2) production, Ca(2+) levels, as well as stomatal closure. The results suggest that CuAO in V. faba guard cells is an essential enzymatic source for H(2)O(2) production in ABA-induced stomatal closure via the degradation of putrescine. Calcium messenger is an important intermediate in this process.
过氧化氢（H₂O₂）是脱落酸（ABA）诱导气孔关闭过程中的一种重要信号。它可由植物中的多种酶合成。在本研究中，对铜胺氧化酶（CuAO）在H₂O₂产生及气孔关闭中的作用进行了研究。外源ABA刺激了蚕豆保卫细胞质外体CuAO活性，增加了H₂O₂的产生及胞质钙离子（[Ca²⁺]cyt）水平，并诱导了气孔关闭。这些过程受到CuAO抑制剂的抑制。在CuAO的代谢产物中，只有H₂O₂能诱导气孔关闭。通过对叶片中酶动力学和多胺含量的分析，腐胺被认为是CuAO的底物。腐胺在调节H₂O₂产生、[Ca²⁺]cyt水平以及气孔关闭方面表现出与ABA相似的作用。结果表明蚕豆保卫细胞中的CuAO是ABA诱导气孔关闭过程中通过腐胺降解产生H₂O₂的重要酶源。钙信使是这一过程中的重要中间体。
