A Patch-Clamp Investigation of the Role of the Phosphatidyl-inositol Pathway in Mediating Plant Cell Responses to Blue Light

利用电生理（贴片夹紧）技术，该研究者已经证明蓝光激活了保护细胞膜上的超极化质子泵。超极化产生钾流入的梯度，假定钾流入通过钾特异性离子通道发生，导致水分吸收、细胞膨胀和气孔打开。本研究的目的是探讨质子泵的蓝光激活和/或钾通道打开的调节是由磷脂酰肌醇（PI）途径介导的。初步实验表明，二酰基甘油类似物（PI通路的一个组成部分）可以促进光刺激下表皮剥皮气孔的开放。膜片夹紧将用于确定这些和其他PI途径的生化调节因子对蓝光刺激的离子泵送和保护细胞原生质体钾通道动力学的影响。拟南芥突变体（phi 3-4）保护细胞对蓝光的电生理反应也将被表征。该突变体缺乏光致性反应，在蓝色光照下气孔开口也减少。蓝光介导植物的多种反应，如气孔的打开以进行气体和水的交换，向光弯曲以及叶绿体的发育。该研究将集中在气孔响应上，并将有助于更清楚地了解植物检测和响应蓝光的细胞机制。

Using electrophysiological (patch clamping) techniques, this investigator has shown that blue light activates a hyperpolarizing proton pump at the guard cell membrane. Hyperpolarization creates a gradient for potassium influx, presumed to occur through potassium-specific ion channels, resulting in water uptake, cell swelling, and stomatal opening. The goals of the proposed research are to investigate the possibility that blue-light-activation of the proton pump and/or regulation of potassium channel opening is mediated by the phosphatidylinositol (PI) pathway. Preliminary experiments indicate that analogs of diacylglycerol, a component of the PI pathway, can enhance light-stimulated opening of stomata in epidermal peels. Patch clamping will be used to determine the effects of these and other biochemical regulators of the PI pathway on blue-light-stimulated ion pumping and potassium channel kinetics of guard cell protoplasts. The electrophysiological response to blue light of guard cells from an Arabidopsis thaliana mutant (phi 3-4) will also be characterized. This mutant lacks a phototropic response, and also exhibits reduced stomatal opening under blue illumination. Blue light mediates a variety of responses in plants, such as opening of stomatal pores to allow gas and water exchange, bending toward light, and chloroplast development. The proposed research will focus on the stomatal response and will contribute to a clearer understanding of the cellular mechanisms by which plants detect and respond to blue light.