Cryptogein-Induced Anion Effluxes Electrophysiological Properties and Analysis of the Mechanisms Through Which They Contribute to the Elicitor-Triggered Cell Death
Cryptogein-Induced Anion Effluxes Electrophysiological Properties and Analysis of the Mechanisms Through Which They Contribute to the Elicitor-Triggered Cell Death
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DOI：
10.4161/psb.2.2.4015
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发表时间：
2007-01-01
影响因子：
2.9
通讯作者：
Wendehenne, David
中科院分区：
文献类型：
--
作者：
Gauthier, Adrien;Lamotte, Olivier;Wendehenne, David
负离子流出是植物细胞对防御反应诱导物的最早反应之一。然而，它们的特性及其在抗病性中的作用仍然几乎未知。我们以前证明，隐地蛋白，烟草防御反应的激发子，诱导硝酸盐（NO3-）流出。这种外排是隐地蛋白触发的过敏反应（HR）的早期先决条件。在这里，我们分析了激发子介导的NO3-流出的电生理特性，并阐明了它导致细胞死亡的机制。应用不连续单电极电压钳技术在烟草细胞引起的隐地蛋白使我们能够记录激活慢型失活阴离子通道电流。隐地蛋白诱导的质膜去极化和Ca 2+内流，一个重要的组成部分，诱导信号HR细胞死亡，防止通过抑制NO3-流出。类似地，药理学阻断阴离子流出抑制空泡塌陷，这是细胞死亡的标志。进一步评估NO3-流出在介导蛋白酶活化中的作用。结果表明，cryptogein诱导活化的三个蛋白酶的表观分子量为95，190和240 kDa。它们的激活独立于阴离子外排而发生，并且与细胞死亡一起被环己酰亚胺和蛋白酶抑制剂PMSF强烈减少。与此相反，NO3-外流被证明是促进积累的转录编码液泡加工酶，一个家庭的蛋白酶以前报道，有助于破坏液泡的完整性观察期间的HR。总的来说，我们的数据表明，阴离子外流是一个早期的先决条件，参与细胞死亡的形态和生化事件。
Anion effluxes are amongst the earliest reactions of plant cells to elicitors of defence responses. However, their properties and their role in disease resistance remain almost unknown. We previously demonstrated that cryptogein, an elicitor of tobacco defence responses, induces a nitrate (NO3-) efflux. This efflux is an early prerequisite to the cryptogein-triggered hypersensitive response (HR). Here, we analyzed the electrophysiological properties of the elicitor-mediated NO3- efflux and clarified the mechanisms through which it contributes to cell death. Application of the discontinuous single electrode voltage-clamp technique in tobacco cells elicited with cryptogein enabled us to record the activation of slow-type deactivating anion channel currents. Cryptogein-induced plasma membrane depolarization and Ca2+ influx, an essential component of elicitor signalling for HR cell death, were prevented by inhibiting the NO3- efflux. Similarly, pharmacological blocking of the anion efflux suppressed vacuolar collapse, a hallmark of cell death. The role of NO3- efflux in mediating proteases activation was further assessed. It is shown that cryptogein induced the activation of three proteases with apparent molecular masses of 95, 190 and 240 kDa. Their activation occurred independently on the anion efflux and, together with cell death, was strongly reduced by cycloheximide and the protease inhibitor PMSF. In contrast, the NO3- efflux was shown to promote the accumulation of transcripts encoding vacuolar processing enzymes, a family of proteases previously reported to contribute to the disruption of vacuole integrity observed during the HR. Collectively, our data indicate that anion efflux is an early prerequisite to morphological and biochemical events participating to cell death.