Riu Young-Sun, Song Hyun-Geun, Kim Hwi-Su, Kong Sam-Geun
Department of Biological Sciences, College of Natural Sciences, Kongju National University, Chungnam 32588, Korea.
Biotechnology Research Institute, Kongju National University, Chungnam 32588, Korea.
Plants (Basel). 2021 Dec 26;11(1):65. doi: 10.3390/plants11010065.
Phototropins (phot1 and phot2) are plant-specific blue light receptors that mediate chloroplast movement, stomatal opening, and phototropism. Phototropin is composed of the N-terminus LOV1 and LOV2 domains and the C-terminus Ser/Thr kinase domain. In previous studies, 35-P2CG transgenic plants expressing the phot2 C-terminal fragment-GFP fusion protein (P2CG) under the control of promoter showed constitutive phot2 responses, including chloroplast avoidance response, stomatal opening, and reduced hypocotyl phototropism regardless of blue light, and some detrimental growth phenotypes. In this study, to exclude the detrimental growth phenotypes caused by the ectopic expression of P2C and to improve leaf transpiration, we used the promoter for the endogenous expression of GFP-fused P2C (GP2C) (P2-GP2C) and the promoter for the guard-cell-specific expression of GP2C (B1-GP2C), respectively. In P2-GP2C plants, GP2C expression induced constitutive phototropin responses and a relatively dwarf phenotype as in 35-P2CG plants. In contrast, B1-GP2C plants showed the guard-cell-specific P2C expression that induced constitutive stomatal opening with normal phototropism, chloroplast movement, and growth phenotype. Interestingly, leaf transpiration was significantly improved in B1-GP2C plants compared to that in P2-GP2C plants and WT. Taken together, this transgenic approach could be applied to improve leaf transpiration in indoor plants.
向光素（phot1和phot2）是植物特有的蓝光受体，介导叶绿体运动、气孔开放和向光性。向光素由N端的LOV1和LOV2结构域以及C端的丝氨酸/苏氨酸激酶结构域组成。在先前的研究中，在启动子控制下表达光2 C端片段-GFP融合蛋白（P2CG）的35-P2CG转基因植物表现出组成型光2反应，包括叶绿体回避反应、气孔开放以及无论有无蓝光下胚轴向光性降低，还有一些有害的生长表型。在本研究中，为了排除由P2C异位表达引起的有害生长表型并改善叶片蒸腾作用，我们分别使用启动子进行GFP融合的P2C（GP2C）的内源表达（P2-GP2C）以及使用启动子进行保卫细胞特异性表达的GP2C（B1-GP2C）。在P2-GP2C植物中，GP2C的表达诱导了组成型向光素反应以及与35-P2CG植物中类似的相对矮小的表型。相比之下，B1-GP2C植物表现出保卫细胞特异性的P2C表达，诱导了组成型气孔开放，同时具有正常的向光性、叶绿体运动和生长表型。有趣的是，与P2-GP2C植物和野生型相比，B1-GP2C植物的叶片蒸腾作用显著提高。综上所述，这种转基因方法可用于改善室内植物的叶片蒸腾作用。
