In plants, environmental stressors trigger plasma membrane depolarizations. Being electrically interconnected via plasmodesmata, proper functional dissection of electrical signaling by electrophysiology is basically impossible. The green alga Chlamydomonas reinhardtii evolved blue light-excited channelrhodopsins (ChR1, 2) to navigate. When expressed in excitable nerve and muscle cells, ChRs can be used to control the membrane potential via illumination. In Arabidopsis plants, we used the algal ChR2-light switches as tools to stimulate plasmodesmata-interconnected photosynthetic cell networks by blue light and monitor the subsequent plasma membrane electrical responses. Blue-dependent stimulations of ChR2 expressing mesophyll cells, resting around −160 to −180 mV, reproducibly depolarized the membrane potential by 95 mV on average. Following excitation, mesophyll cells recovered their prestimulus potential not without transiently passing a hyperpolarization state. By combining optogenetics with voltage-sensing microelectrodes, we demonstrate that plant plasma membrane AHA-type H⁺-ATPase governs the gross repolarization process. AHA2 protein biochemistry and functional expression analysis in Xenopus oocytes indicates that the capacity of this H⁺ pump to recharge the membrane potential is rooted in its voltage- and pH-dependent functional anatomy. Thus, ChR2 optogenetics appears well suited to noninvasively expose plant cells to signal specific depolarization signatures. From the responses we learn about the molecular processes, plants employ to channel stress-associated membrane excitations into physiological responses.

在植物中，环境胁迫源触发质膜去极化。通过电浆瘤电互连，通过电生理学对电信号进行适当的功能解剖基本上是不可能的。绿藻衣藻（Chlamydomonas reinhardtii）进化出蓝色光激发的通道视紫红质（ChR1、2）来进行导航。当在可兴奋的神经和肌肉细胞中表达时，ChRs可用于通过照明控制膜电位。在拟南芥中在植物中，我们使用藻类ChR2-light开关作为工具，通过蓝光刺激质膜间相互连接的光合细胞网络，并监测随后的质膜电响应。依赖于ChR2的叶肉细胞表达的蓝色依赖性刺激（介于-160至-180 mV之间）可再现地使膜电位平均去极化95 mV。激发后，叶肉细胞在没有暂时通过超极化状态的情况下恢复了其刺激前的潜能。通过将光遗传学与电压感应微电极相结合，我们证明了植物质膜AHA型H ⁺ -ATPase控制着总的复极化过程。非洲爪蟾卵母细胞中AHA2蛋白的生化和功能性表达分析表明，这种H的能力⁺泵来补充膜电位的原因在于其依赖于电压和pH的功能解剖。因此，ChR2的光遗传学似乎非常适合非侵入性地暴露植物细胞以发出特定的去极化信号。从反应中我们了解了分子过程，植物利用该反应将与压力相关的膜激发转化为生理反应。