Liu K, Luan S
Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA.
Plant Cell. 1998 Nov;10(11):1957-70. doi: 10.1105/tpc.10.11.1957.
Guard cell turgor responds to the osmogradient across the plasma membrane and controls the stomatal aperture. Here, we report that guard cells utilize voltage-dependent K+ channels as targets of the osmosensing pathway, providing a positive feedback mechanism for stomatal regulation. When exposed to a hypotonic condition, the inward K+ current (IKin) was highly activated, whereas the outward K+ current (IKout) was inactivated. In contrast, hypertonic conditions inactivated the IKin while activating IKout. Single-channel recording analyses indicated that an alteration in channel opening frequency was responsible for regulating IKin and IKout under different osmotic conditions. Further studies correlate osmoregulation of IKin with the pattern of organization of actin filaments, which may be a critical component in the osmosensing pathway in plant cells.
保卫细胞膨压响应跨质膜的渗透梯度并控制气孔孔径。在此，我们报道保卫细胞利用电压依赖性钾通道作为渗透感应途径的靶点，为气孔调节提供一种正反馈机制。当暴露于低渗条件下时，内向钾电流（IKin）被高度激活，而外向钾电流（IKout）被失活。相反，高渗条件使IKin失活，同时激活IKout。单通道记录分析表明，通道开放频率的改变是在不同渗透条件下调节IKin和IKout的原因。进一步的研究将IKin的渗透调节与肌动蛋白丝的组织模式相关联，肌动蛋白丝可能是植物细胞渗透感应途径中的关键组成部分。
