Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan.
Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Chikusa, Nagoya 464-8602, Japan.
Sci Rep. 2017 Mar 30;7:45586. doi: 10.1038/srep45586.
Stomata in the plant epidermis open in response to blue light and affect photosynthesis and plant growth by regulating CO uptake and transpiration. In stomatal guard cells under blue light, plasma membrane H-ATPase is phosphorylated and activated via blue light-receptor phototropins and a signaling mediator BLUS1, and H-ATPase activation drives stomatal opening. However, details of the signaling between phototropins and H-ATPase remain largely unknown. In this study, through a screening of specific inhibitors for the blue light-dependent H-ATPase phosphorylation in guard cells, we identified a Raf-like protein kinase, BLUE LIGHT-DEPENDENT H-ATPASE PHOSPHORYLATION (BHP). Guard cells in the bhp mutant showed impairments of stomatal opening and H-ATPase phosphorylation in response to blue light. BHP is abundantly expressed in the cytosol of guard cells and interacts with BLUS1 both in vitro and in vivo. Based on these results, BHP is a novel signaling mediator in blue light-dependent stomatal opening, likely downstream of BLUS1.
植物表皮中的气孔会对蓝光做出反应而开启，通过调节 CO2 吸收和蒸腾作用来影响光合作用和植物生长。在蓝光下的气孔保卫细胞中，质膜 H+-ATP 酶通过蓝光受体向光素和信号介质 BLUS1 发生磷酸化和激活，而 H+-ATP 酶的激活则驱动气孔开启。然而，向光素和 H+-ATP 酶之间的信号转导细节在很大程度上仍不清楚。在这项研究中，通过筛选蓝光依赖性 H+-ATP 酶在保卫细胞中磷酸化的特定抑制剂，我们鉴定出一种 Raf 样蛋白激酶，即蓝光依赖性 H+-ATP 酶磷酸化（BHP）。bhp 突变体中的保卫细胞在蓝光响应下表现出气孔开启和 H+-ATP 酶磷酸化受损。BHP 在保卫细胞质体中大量表达，并在体外和体内与 BLUS1 相互作用。基于这些结果，BHP 是蓝光依赖性气孔开启的一种新的信号转导介质，可能是 BLUS1 的下游。
