Arabidopsis root K+-efflux conductance activated by hydroxyl radicals: single-channel properties, genetic basis and involvement in stress-induced cell death
Arabidopsis root K+-efflux conductance activated by hydroxyl radicals: single-channel properties, genetic basis and involvement in stress-induced cell death
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DOI：
10.1242/jcs.064352
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发表时间：
2010-05-01
影响因子：
4
通讯作者：
Yurin, Vladimir
中科院分区：
文献类型：
--
作者：
Demidchik, Vadim;Cuin, Tracey A.;Yurin, Vladimir
活性氧(ROS)是植物逆境反应、信号传递、发育和许多其他过程的中心。在这项研究中，质膜羟基自由基(HR)激活的K+通道在胁迫伴随ROS的产生过程中负责根细胞的K+外流。该通道具有16pS的单位电导，对钙离子、四乙基铵、Ba2+、Cs+和自由基清除剂敏感。在Gork1-1突变体中没有发现该通道，该突变体缺乏一个主要的质膜外向整流性K+通道。在完整的拟南芥根中，HRs和胁迫都诱导了显著的K+外流，而Gork1-1植株的K+外流要小得多。电子顺磁共振波谱测试表明，氯化钠能刺激根中HR的产生，这可能导致K+通道的激活。在动物中，HR激活K+-外流通道可引发程序性细胞死亡(PCD)。在Gork1-1和用K+通道阻滞剂或HR清除剂处理的野生型植株中，拟南芥根中PCD症状的发展要慢得多。因此，与动物相似，植物HR激活的K+通道也参与了PCD。总之，本研究为ROS对植物阳离子转运的调控提供了新的见解，并证明了植物HR激活的K+通道可能的生理特性。
Reactive oxygen species (ROS) are central to plant stress response, signalling, development and a multitude of other processes. In this study, the plasma-membrane hydroxyl radical (HR)-activated K+ channel responsible for K+ efflux from root cells during stress accompanied by ROS generation is characterised. The channel showed 16-pS unitary conductance and was sensitive to Ca2+, tetraethylammonium, Ba2+, Cs+ and free-radical scavengers. The channel was not found in the gork1-1 mutant, which lacks a major plasma-membrane outwardly rectifying K+ channel. In intact Arabidopsis roots, both HRs and stress induced a dramatic K+ efflux that was much smaller in gork1-1 plants. Tests with electron paramagnetic resonance spectroscopy showed that NaCl can stimulate HR generation in roots and this might lead to K+-channel activation. In animals, activation of K+-efflux channels by HRs can trigger programmed cell death (PCD). PCD symptoms in Arabidopsis roots developed much more slowly in gork1-1 and wild-type plants treated with K+-channel blockers or HR scavengers. Therefore, similar to animal counterparts, plant HR-activated K+ channels are also involved in PCD. Overall, this study provides new insight into the regulation of plant cation transport by ROS and demonstrates possible physiological properties of plant HR-activated K+ channels.