脱落酸抑制蓝光依赖气孔开放运动的生理机制分析

Mechanism of Abscisic Acid Inhibits Blue Light-Dependent Stomatal Opening Movement by Electrophysiologic Analysis in Vicia faba Guard Cells

以蚕豆(Vicia fabaL.)为材料,采用表皮条生物学分析技术、远红外成像技术以及电生理膜片钳技术,研究逆境信号脱落酸(ABA)和蓝光信号对蚕豆叶片表皮气孔运动及质膜K+通道的影响,以探讨ABA调节蓝光诱导的气孔开放运动的生理机制.结果表明:(1)100μmol?m-2?s-1蓝光能显著诱导气孔开放,该效应可被ABA以浓度依赖的方式抑制,并以10μmol?L-1ABA抑制效应最为明显.(2)100μmol?m-2?s-1蓝光处理能明显促使蚕豆叶面温度下降,而10μmol?L-1ABA可显著阻止蓝光诱导的蚕豆叶面温度下降.(3)100μmol?m-2?s-1蓝光可明显激活保卫细胞质膜内向K+通道,处理5 min后内向K+电流增加58%;对于1和10μmol?L-1ABA预处理蚕豆保卫细胞原生质体,在蓝光处理5 min后其内向K+电流增加值分别被抑制25%和51%,但10μmol?L-1ABA并不明显抑制壳梭孢菌素(质膜H+-ATP酶永久性激活剂)诱导的保卫细胞内向K+电流上升.研究发现,逆境信号ABA可能主要通过抑制蓝光信号转导中质膜H+-ATP酶上游位点,阻断蓝光激活的保卫细胞质膜内向K+通道,抑制蓝光诱导的气孔开放,以避免水分的过度散失,适应水分胁迫.

Broad bean（Vicia faba L.） was employed to analyze the mechanism of abscisic acid（ABA）-inhibited blue light（BL）-dependent stomatal opening movement,through epidermal biological analysis,infrared imaging and electrophysiology patch clamp technique.The results showed that 100 μmol·m-2·s-1 BL significantly induced stomatal opening,which was blocked by ABA,at concentration of 1 or 10 μmol·L-1.Thermal image analysis of different temperatures of V.faba leaves with infrared imaging techniques,100 μmol·m-2·s-1 BL is indeed able to lead to a remarkable decline of the temperature of plant leave surface,but the decline of temperature will be unconspicuous by BL if V.faba seedling was treated by 10 μmol·L-1 ABA.To gain further insights into function of ABA in BL-regulated stomatal movement,V.faba guard cell protoplasts were patch-clamped in a whole-cell configuration.BL pulses（100 μmol·m-2·s-1 for 30 s） effectively activate inward rectifying K＋ channels,leading to an increase in inward currents by 58% in V.faba guard cells.ABA,at concentration of 1 or 10 μmol·L-1,significantly inhibits inward rectifying K＋ channels and blockes BL-induced the increase of inward K＋ currents by 25% and 51%,respectively.However,ABA showed little effects of inhibition on the increase of inward K＋ currents induced by fusicoccin（FC,an activator for H＋-ATPase）.These results suggest that ABA inhibits BL-dependent stomatal opening through blocking the BL-activated plasma membrane K＋ channels and K＋ influx to avoid excessive transpiration under water stress.Moreover,the inhibition sites by ABA maybe mainly reflect upstream of H＋-ATPase in the BL signaling pathway of guard cells.