Plant adaptation to fluctuating environment and biomass production are strongly dependent on guard cell potassium channels
Plant adaptation to fluctuating environment and biomass production are strongly dependent on guard cell potassium channels
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DOI：
10.1073/pnas.0709732105
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发表时间：
2008-04-01
影响因子：
11.1
通讯作者：
Sentenac, Herve
中科院分区：
文献类型：
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作者：
Lebaudy, Anne;Vavasseur, Alain;Sentenac, Herve
至少有四个基因编码质膜内向钾通道（Kin通道）在拟南芥保卫细胞中表达。通过破坏主要Kin通道基因和表达显性负通道构建体来工程化双突变体植物。利用膜片钳技术发现该突变体完全丧失了保卫细胞钾离子通道（GCK（in））活性，为研究该活性在植物中的作用提供了一个模型。GCKin活性被认为是由膜超极化触发的气孔开放的一个重要效应，从而在黎明蓝光诱导的气孔开放。它提高了气孔对外部或内部信号（光，CO2可用性和蒸发需求）的反应。当植物生长在生理浓度的Na+存在下时，它保护气孔功能免受Na+的不利影响，这可能是通过使保卫细胞在气孔开放期间选择性地和快速地吸收K+而不是Na+，从而防止Na+对气孔关闭的不利影响。它也被证明是一个关键组成部分的机制，基础的昼夜节律气孔开放，这是已知的门气孔响应细胞外和细胞内信号。最后，在一个气象情景与较高的光照强度，在第一个小时的生长期，GCK（在）活动被发现，允许一个强大的增加（35%），在植物生物量生产。因此，大量多样性的方法表明，GCKin活性发挥多效性的作用，至关重要的是有助于植物适应波动和压力的自然环境。
At least four genes encoding plasma membrane inward K+ channels (Kin channels) are expressed in Arabidopsis guard cells. A double mutant plant was engineered by disruption of a major Kin channel gene and expression of a dominant negative channel construct. Using the patch-clamp technique revealed that this mutant was totally deprived of guard cell K-in channel (GCK(in)) activity, providing a model to investigate the roles of this activity in the plant. GCKin activity was found to be an essential effector of stomatal opening triggered by membrane hyperpolarization and thereby of blue light-induced stomatal opening at dawn. It improved stomatal reactivity to external or internal signals (light, CO2 availability, and evaporative demand). It protected stomatal function against detrimental effects of Na+ when plants were grown in the presence of physiological concentrations of this cation, probably by enabling guard cells to selectively and rapidly take up K+ instead of Na+ during stomatal opening, thereby preventing deleterious effects of Na+ on stomatal closure. It was also shown to be a key component of the mechanisms that underlie the circadian rhythm of stomatal opening, which is known to gate stomatal responses to extracellular and intracellular signals. Finally, in a meteorological scenario with higher light intensity during the first hours of the photophase, GCK(in) activity was found to allow a strong increase (35%) in plant biomass production. Thus, a large diversity of approaches indicates that GCKin activity plays pleiotropic roles that crucially contribute to plant adaptation to fluctuating and stressing natural environments.