Ca^(2+)参与水杨酸诱导蚕豆气孔运动时的信号转导

Ca^(2+)is Involved in the Signal Transduction During Stomatal Movement in Vicia faba L. Induced by Salicylic Acid

在一定条件下 ,外源水杨酸 (SA)可以诱导蚕豆(ViciafabaL .)气孔关闭 ,阻止气孔张开。以Fluo 3 AM作为Ca2 + 的荧光探针 ,利用激光共聚焦扫描显微技术 ,对水杨酸调控气孔运动中保卫细胞胞质Ca2 + 的变化趋势及Ca2 + 的来源进行了研究。结果表明 ,水杨酸可引起胞质Ca2 + 增加 ,这种变化发生在气孔开度改变之前。Ca2 + 螯合剂BAPTA (1,2 bis(2 aminophe noxy)ethane N ,N ,N′,N′ tetraaceticacid ,1mmol/L)几乎可以完全抑制水杨酸诱导气孔开度减小的作用 ;胞外Ca2 + 螯合剂EGTA(2mmol/L)、质膜Ca2 + 通道抑制剂尼群地平 (nifedipine,NIF ,1μmol/L)和LaCl3 (1mmol/L)可不同程度地减弱水杨酸诱导气孔关闭的效应。BAPTA(1mmol/L)预处理后 ,水杨酸不再引起胞质Ca2 + 含量改变 ;尼群地平能够降低水杨酸引起的胞质Ca2 + 增加的幅度。说明Ca2 + 可能参与水杨酸诱导气孔运动的信号转导。水杨酸引起胞内升高的Ca2 +可能既来自胞外又来自胞内 ,胞内Ca2 + 库可能是其主要来源。

Using Fluo-3-AM as the Ca 2+ probe, cytosolic free calcium ( i) changes in guard cells of Vicia faba L. in response to exogenous salicylic acid (SA) were measured by confocal laser scanning microscopy (CLSM), and the specificity of i changes in the regulation of stomatal movement by SA were studied. The results showed that i increased within a few seconds after addition of SA, and kept at high levels for several minutes, then declined to the initial level before stomatal aperture changed(Fig.1). We postulated that Ca 2+ involved in the signal transduction of SA regulation of stomatal movement. When Ca 2+ channels in plasma membrane were blocked by extracellular Ca 2+ chelating reagent EGTA (Fig.2), LaCl 3 (Fig.3), or addition of nifedipine(NIF)(Fig.4), the effects of SA on stomatal closure were suppressed differently. Intracellular Ca 2+ chelation with 1,2-bis (2-amino phenoxy)ethane-N,N,N′,N′-tetraacetic acid (BAPTA) almost completely abolished the stomatal closure induced by SA (Fig.5). In addition, the extent of i increase by 1 mmol/L SA after pretreatment with NIF was lower than that without NIF pretreatment; almost no i increase was observed after pretreatment with BAPTA(Fig.6). Those results suggest that i increase induced by SA comes mainly from the intracellular storage and partly from the extracellular space.