不同浓度H2O2可使蚕豆(Vicia faba L.)叶片气孔关闭，抑制气孔张开，10 mmol/L的H2O2最有效，10μmol/L的H2O2仍明显使气孔关闭。且10 μmol/L的H2O2抑制气孔张开作用能被EGTA所消除，表明Ca2+参与低浓度H2O2使气孔关闭的过程。2 mmol/L的H2O2可使质膜内向K+通道电流明显减小，而外向K+通道电流显著增加。因此，H2O2促进蚕豆气孔关闭主要是通过抑制K+通过保卫细胞质膜内向流入，或加强K+外向流出实现的。%H2O2, a species of active oxygen, at 10 mmol/L could induce stomatal closure and inhibit stomatal opening (Fig.1). The effect of H2O2-inducing stomatal closure could be 10 mmol/L Vc, but Vc in lower concentration(1 mmoL/L) had no such effect(Fig.2). EGTA (chelator of Ca2+) and phenothiazine (antagonist of calmodulin) had no effects on the H2O2-induced stomatal closure(Fig.3), but they could abolish the effects of 10 μmol/L H2O2 on the stomatal aperture in Vicia faba(Fig.4). In addition, the K+ channel current in plasma membrane of guard cell was recorded by whole-cell configuration of patch clamp. On adding 2 mmoL/L H2O2, voltage-clamp measurements showed that the inward K+ channel current significantly decreased 5 min after H2O2 treatment, and the outward K+ channel current rose markedly about 30 min after H2O2 treatment(Fig.6). This suggests that H2O2-induced stomatal closure may be the result of the inhibition of K+ uptake and the evocation of K+ release through K+ channels on plasma membrane in guard cells.
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