Data_Sheet_5_Identification of Genes Preferentially Expressed in Stomatal Guard Cells of Arabidopsis thaliana and Involvement of the Aluminum-Activated Malate Transporter 6 Vacuolar Malate Channel in Stomatal Opening.PDF

Stomatal guard cells (GCs) are highly specialized cells that respond to various stimuli, such as blue light (BL) and abscisic acid, for the regulation of stomatal aperture. Many signaling components that are involved in the stomatal movement are preferentially expressed in GCs. In this study, we identified four new such genes in addition to an aluminum-activated malate transporter, ALMT6, and GDSL lipase, Occlusion of Stomatal Pore 1 (OSP1), based on the expression analysis using public resources, reverse transcription PCR, and promoter-driven β-glucuronidase assays. Some null mutants of GC-specific genes evidenced altered stomatal movement. We further investigated the role played by ALMT6, a vacuolar malate channel, in stomatal opening. Epidermal strips from an ALMT6-null mutant exhibited defective stomatal opening induced by BL and fusicoccin, a strong plasma membrane H+-ATPase activator. The deficiency was enhanced when the assay buffer [Cl–] was low, suggesting that malate and/or Cl– facilitate efficient opening. The results indicate that the GC-specific genes are frequently involved in stomatal movement. Further detailed analyses of the hitherto uncharacterized GC-specific genes will provide new insights into stomatal regulation.

气孔保卫细胞（GCs）为一种高度专业化的细胞，对多种刺激，如蓝光（BL）和脱落酸，作出响应，以调节气孔的开闭。众多参与气孔运动调控的信号组分在GCs中优先表达。本研究基于公共资源表达分析、逆转录PCR和启动子驱动的β-葡萄糖苷酶检测，在铝激活的苹果酸转运蛋白ALMT6和GDSL脂肪酶、气孔孔隙封闭1（OSP1）之外，鉴定出四个新的此类基因。GC特异性基因的某些缺失突变体表现出气孔运动异常。我们进一步研究了ALMT6，一种液泡苹果酸通道，在气孔开放中的作用。ALMT6基因敲除突变体的表皮条在受到BL和富马酸菌素（fusicoccin，一种强效质膜H+-ATP酶激活剂）诱导时，表现出气孔开启缺陷。当检测缓冲液中的[Cl–]浓度较低时，这种缺陷更加明显，表明苹果酸和/或Cl–有助于气孔的效率开启。研究结果指出，GC特异性基因常参与气孔运动。对至今尚未明确表征的GC特异性基因进行更深入的详细分析，将有助于揭示气孔调控的新机制。