McAdam Erin L, Brodribb Timothy J, McAdam Scott A M
School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania, 7001, Australia.
Plant Cell Environ. 2017 May;40(5):741-747. doi: 10.1111/pce.12893. Epub 2017 Mar 16.
Reactive oxygen species (ROS) are widely recognized as important regulators of stomatal aperture and plant gas exchange. The pathways through which stomata perceive ROS share many common linkages with the well characterized signalling pathway for the hormone abscisic acid (ABA), a major driver of stomatal closure. Given reports that ABA receptor mutants have no stomatal response to ozone-triggered ROS production, as well as evidence that all steps in the ABA biosynthetic pathway can be non-enzymatically converted by ROS, here we investigated the possibility that ozone closes stomata by directly converting ABA precursors to ABA. In plants where stomata were responsive to ozone, we found that foliar ABA levels rapidly increased upon exposure to ozone. Recovery of gas exchange post-exposure occurred only when ABA levels declined. Our data suggest that stomatal closure in response to ozone exposure occurs as a result of direct oxidation of ABA precursors leading to ABA production, but the importance of this ROS interaction remains uncertain under normal photosynthetic conditions.
活性氧（ROS）被广泛认为是气孔孔径和植物气体交换的重要调节因子。气孔感知ROS的途径与已充分表征的激素脱落酸（ABA）信号通路有许多共同联系，ABA是气孔关闭的主要驱动因素。鉴于有报道称ABA受体突变体对臭氧触发的ROS产生没有气孔反应，以及有证据表明ABA生物合成途径中的所有步骤都可以被ROS非酶促转化，我们在此研究了臭氧通过直接将ABA前体转化为ABA来关闭气孔的可能性。在气孔对臭氧有反应的植物中，我们发现暴露于臭氧后叶片ABA水平迅速升高。暴露后气体交换的恢复仅在ABA水平下降时发生。我们的数据表明，对臭氧暴露的气孔关闭是由于ABA前体直接氧化导致ABA产生的结果，但在正常光合条件下这种ROS相互作用的重要性仍不确定。
