Distinct Cellular Locations of Carbonic Anhydrases Mediate Carbon Dioxide Control of Stomatal Movements
Distinct Cellular Locations of Carbonic Anhydrases Mediate Carbon Dioxide Control of Stomatal Movements
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DOI：
10.1104/pp.15.00646
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发表时间：
2015-10-01
期刊：
影响因子：
7.4
通讯作者：
Schroeder, Julian I.
中科院分区：
文献类型：
--
作者：
Hu, Honghong;Rappel, Wouter-Jan;Schroeder, Julian I.
叶片中二氧化碳（CO2）的升高使气孔关闭。研究表明，β-碳酸酐酶（β CA 1和β CA 4）通过在保卫细胞中催化传递CO2信号在快速CO2诱导的气孔运动中发挥关键作用。然而，潜在的机制仍然不清楚，因为初步研究表明，这些拟南芥（拟南芥）β CA靶向不同的细胞内区室后，在烟草（烟草）细胞中表达。这些酶的细胞位置在天然保卫细胞中起着关键作用，在CO2调节气孔运动仍然未知。在这里，我们表达荧光标记的CA在保卫细胞的ca 1ca 4双突变体植物，并表明β CA 4在质膜和β CA 1在原生保卫细胞叶绿体的特定位置，每个可以介导快速CO2控制气孔运动。使用哺乳动物α CAII-黄色荧光蛋白在保卫细胞中的定位和互补分析进一步表明，细胞质定位也足以恢复气孔导度的CO2调节。细胞CO2催化的数学建模表明，保卫细胞中的细胞内HCO 3浓度变化的动态可以由CA的质膜和细胞质定位驱动，但不清楚叶绿体靶向。此外，建模支持的概念，即保卫细胞的细胞内HCO 3浓度的动态是一个关键的机制，在介导CO2调节气孔运动，但存在一个额外的叶绿体作用的CA尚未被确定。
Elevated carbon dioxide (CO2) in leaves closes stomatal apertures. Research has shown key functions of the beta-carbonic anhydrases (beta CA1 and beta CA4) in rapid CO2-induced stomatal movements by catalytic transmission of the CO2 signal in guard cells. However, the underlying mechanisms remain unclear, because initial studies indicate that these Arabidopsis (Arabidopsis thaliana) beta CAs are targeted to distinct intracellular compartments upon expression in tobacco (Nicotiana benthamiana) cells. Which cellular location of these enzymes plays a key role in native guard cells in CO2-regulated stomatal movements remains unknown. Here, we express fluorescently tagged CAs in guard cells of ca1ca4 double-mutant plants and show that the specific locations of beta CA4 at the plasma membrane and beta CA1 in native guard cell chloroplasts each can mediate rapid CO2 control of stomatal movements. Localization and complementation analyses using a mammalian alpha CAII-yellow fluorescent protein in guard cells further show that cytoplasmic localization is also sufficient to restore CO2 regulation of stomatal conductance. Mathematical modeling of cellular CO2 catalysis suggests that the dynamics of the intracellular HCO3- concentration change in guard cells can be driven by plasma membrane and cytoplasmic localizations of CAs but not as clearly by chloroplast targeting. Moreover, modeling supports the notion that the intracellular HCO3- concentration dynamics in guard cells are a key mechanism in mediating CO2-regulated stomatal movements but that an additional chloroplast role of CAs exists that has yet to be identified.