Samuilov V D, Kiselevsky D B, Sinitsyn S V, Shestak A A, Lagunova E M, Nesov A V
Department of Physiology of Microorganisms, Biological Faculty, Lomonosov Moscow State University, 119992 Moscow, Russia.
Biochemistry (Mosc). 2006 Apr;71(4):384-94. doi: 10.1134/s0006297906040067.
H2O2 intensifies CN(-)-induced apoptosis in stoma guard cells and to lesser degree in basic epidermal cells in peels of the lower epidermis isolated from pea leaves. The maximum effect of H2O2 on guard cells was observed at 10(-4) M. By switching on non-cyclic electron transfer in chloroplasts menadione and methyl viologen intensified H2O2 generation in the light, but prevented the CN--induced apoptosis in guard cells. The light stimulation of CN- effect on guard cell apoptosis cannot be caused by disturbance of the ribulose-1,5-bisphosphate carboxylase function and associated OH* generation in chloroplasts with participation of free transition metals in the Fenton or Haber-Weiss type reactions as well as with participation of the FeS clusters of the electron acceptor side of Photosystem I. Menadione and methyl viologen did not suppress the CN(-)-induced apoptosis in epidermal cells that, unlike guard cells, contain mitochondria only, but not chloroplasts. Quinacrine and diphenylene iodonium, inhibitors of NAD(P)H oxidase of cell plasma membrane, had no effect on the respiration and photosynthetic O2 evolution by leaf slices, but prevented the CN(-)-induced guard cell death. The data suggest that NAD(P)H oxidase of guard cell plasma membrane is a source of reactive oxygen species (ROS) needed for execution of CN(-)-induced programmed cell death. Chloroplasts and mitochondria were inefficient as ROS sources in the programmed death of guard cells. When ROS generation is insufficient, exogenous H2O2 exhibits a stimulating effect on programmed cell death. H2O2 decreased the inhibitory effects of DCMU and DNP-INT on the CN(-)-induced apoptosis of guard cells. Quinacrine, DCMU, and DNP-INT had no effect on CN(-)-induced death of epidermal cells.
过氧化氢会加剧豌豆叶片下表皮分离的表皮条中保卫细胞因氰化物诱导的凋亡，而对基本表皮细胞的影响程度较小。在10⁻⁴ M时观察到过氧化氢对保卫细胞的最大效应。通过开启叶绿体中的非循环电子传递，甲萘醌和甲基紫精在光照下增强了过氧化氢的生成，但阻止了氰化物诱导的保卫细胞凋亡。氰化物对保卫细胞凋亡的光照刺激作用，并非由1,5 - 二磷酸核酮糖羧化酶功能紊乱以及叶绿体中相关的羟基自由基生成所引起，这些反应涉及游离过渡金属参与芬顿或哈伯 - 维希类型反应，以及光系统I电子受体侧的铁硫簇参与。甲萘醌和甲基紫精并未抑制表皮细胞中氰化物诱导的凋亡，与保卫细胞不同，表皮细胞仅含有线粒体，而不含叶绿体。喹吖因和二苯基碘鎓，细胞膜NAD(P)H氧化酶的抑制剂，对叶片切片的呼吸作用和光合放氧没有影响，但阻止了氰化物诱导的保卫细胞死亡。数据表明，保卫细胞质膜的NAD(P)H氧化酶是氰化物诱导的程序性细胞死亡所必需的活性氧（ROS）来源。在保卫细胞的程序性死亡中，叶绿体和线粒体作为ROS来源的效率较低。当ROS生成不足时，外源性过氧化氢对程序性细胞死亡具有刺激作用。过氧化氢降低了二氯苯基二甲基脲（DCMU）和DNP - INT对氰化物诱导的保卫细胞凋亡的抑制作用。喹吖因、DCMU和DNP - INT对氰化物诱导的表皮细胞死亡没有影响。
