蛋白激酶组在玉米叶片ABA和H202诱导抗氧化防护中的作用

蛋白磷酸化在植物细胞脱落酸（ABA）介导的信号转导中起重要作用。然而，很多参与ABA信号途径的蛋白元件仍不清楚。使用改进的体外激酶试验方法的研究结果表明，在玉米叶片中，ABA和H2O2能够快速活化蛋白激酶总活性和ca^2＋依赖型蛋白激酶总活性；ABA诱导的蛋白激酶总活性增加可以被活性氧的抑制剂和清除剂抑制，蛋白激酶抑制剂不仅可以降低ABA和H2O2诱导的激酶活性增加，而且也可以弱化它们对抗氧化防护酶活性的诱导作用；ABA和H2O2引发的蛋白磷酸化作用显著居先于它们诱导的抗氧化防护作用。使用凝胶激酶试验方法进行研究发现，一组分子量分别为66kDa，52kDa，49kDa和35kDa的蛋白激酶可能介导了ABA和H2O2诱导的抗氧化防护反应，并且66kDa和49kDa的蛋白激酶可能在ROS的下游起作用，而52kDa和35kDa的蛋白激酶可能在ABA和ROS的下游起作用。

Role of Protein Kinases in Abscisic Acid and H202 Induced Antioxidant Defense in Maize

Protein phosphorylation plays a central role in mediating abscisic acid （ABA） signaling transduction in plant cells, whereas many of the sensory proteins involving in ABA signaling pathway remain unclear. Here, using a modified in vitro kinase assay, our results showed that ABA and H202 induced a rapid activation of total protein kinases and calcium dependent protein kinases in the leaves of maize seedlings. However, ABA-induced activation of protein kinases was inhibited by reactive oxygen species （ROS） inhibitors or scavengers. Protein kinase inhibitors decelerated not only the ABA and H20g-induced kinase activity but also ABA or H2 02-induced antioxidant enzyme activity. Protein phosphorylation caused by ABA and H202 preceded ABA or H202-induced antioxidant defense obviously. Using in-gel kinase assays, our results showed that several protein kinases with molecular masses of 66 kDa, 52 kDa, 49 kDa and 35 kDa respectively might mediate ABA and HaO2-induced antioxidant defense. And the 66 kDa and 49 kDa protein kinases may act downstream of ROS, and the 52 kDa and 35 kDa protein kinases may act between ABA and ROS in ABA-induced antioxidant defensive signaling.