Huang Ai-Xia, Wang Yong-Shun, She Xiao-Ping, Mu Juan, Zhao Jin-Liang
College of Life Sciences, Shaanxi Normal University, Xi'an 710062, China.
Funct Plant Biol. 2015 Nov;42(11):1057-1067. doi: 10.1071/FP15172.
Hydrogen peroxide is an important intermediate in darkness-induced stomatal closure. In the present work, we provide evidence that copper amine oxidase (CuAO) was involved in H2O2 production in darkness-induced stomatal closure in Vicia faba L. Darkness activated CuAO in intercellular washing fluid from leaves. Aminoguanidine (AG) and 2-bromoethylamine (BEA), which were both irreversible inhibitors of CuAO, significantly suppressed darkness-induced stomatal closure and H2O2 generation. The effects of AG and BEA were reversed only by H2O2 but not by other products of CuAO. These results indicate that CuAO participates in darkness-induced stomatal closure through its reaction product, H2O2. Furthermore, darkness-induced nitric oxide (NO) production and cytosolic alkalinisation were obviously inhibited by AG and BEA, and only H2O2, among the products of CuAO, could reverse the effects, implying that the CuAO-catalysed product H2O2 is required for NO production and cytosolic alkalinisation to a large extent in darkness-induced stomatal closure. In addition, butyric acid blocked but methylamine enhanced the ability of H2O2 to reverse the effect of BEA on NO production, suggesting that cytosolic alkalinisation is involved in CuAO-mediated NO generation in darkness-induced stomatal closure.
过氧化氢是黑暗诱导气孔关闭过程中的一种重要中间体。在本研究中，我们提供证据表明铜胺氧化酶（CuAO）参与了蚕豆黑暗诱导气孔关闭过程中过氧化氢的产生。黑暗激活了叶片细胞间清洗液中的CuAO。氨基胍（AG）和2-溴乙胺（BEA）均为CuAO的不可逆抑制剂，它们显著抑制了黑暗诱导的气孔关闭和过氧化氢的生成。AG和BEA的作用仅能被过氧化氢逆转，而不能被CuAO的其他产物逆转。这些结果表明，CuAO通过其反应产物过氧化氢参与黑暗诱导的气孔关闭。此外，AG和BEA明显抑制了黑暗诱导的一氧化氮（NO）产生和胞质碱化，并且在CuAO的产物中，只有过氧化氢能够逆转这些作用，这意味着在黑暗诱导的气孔关闭过程中，CuAO催化产物过氧化氢在很大程度上是NO产生和胞质碱化所必需的。此外，丁酸阻断但甲胺增强了过氧化氢逆转BEA对NO产生影响的能力，表明胞质碱化参与了黑暗诱导气孔关闭过程中CuAO介导的NO生成。
