Ion Channel Regulation in Higher Plants

研究表明，钙离子和信号调节离子通道可能在植物细胞信号转导中发挥核心作用。保卫细胞为研究植物信号提供了一个理想的系统，因为这些细胞在调节气体交换的过程中对激素和光刺激做出动态反应。最近的数据表明，Guard CLL质膜离子通道的钙调节为生理上观察到的钙依赖的气孔运动提供了基础。初步结果表明，脱落酸诱导胞质钙的增加，进而可能触发气孔关闭，从而保护植物免受干燥。这项研究的目的是要准确了解胞内钙离子和其他离子调节内向整流钾通道的分子机制，以及脱落酸控制这些过程的机制。分离的保卫细胞将通过同步膜片钳分析和细胞内钙的光度测量进行研究，从而可以直接研究细胞内和细胞外调节剂对信号事件的影响。从这些研究中获得的知识将有助于我们理解控制植物叶片中气体和水交换的分子机制，并将为高等植物细胞中离子通道的生物物理和生化调控提供定量的描述。

Research indicates that calcium ions and signal-modulated ion channels may play a central role in plant cellular signal transduction. Guard cells provide an ideal system for the study of plant signaling, as these cells respond dynamically to hormone and light stimuli in regulating gas exchange. Recent data suggest that calcium regulation of ion channels in the plasma membrane of guard clls provides a basis for physiologically- observed calcium dependent stomatal movements. Preliminary results show that abscisic acid induces increases in cytosolic calcium, which in turn may trigger stomatal closing, thus protecting plants from desiccation. The goals of the proposed research are to achieve an accurate understanding of the molecular mechanisms by which cytosolic calcium and other ions regulate inward rectifying potassium channels and by which mechanisms abscisic acid exerts control over these processes. Isolated guard cells will be studied by simultaneous patch clamp analysis and photometric measurements of cytosolic calcium, allowing the direct investigation of effects of cytosolic and extracellular modulators on signaling events. The knowledge gained from these studies will contribute substantially to our understanding of the molecular mechanisms controlling gas and water exchange in the leaves of plants and will provide a quantitative description of biophysical and biochemical regulation of ion channels in higher plant cells.