Ca^(2+)位于H_2O_2上游参与H_2S诱导的拟南芥气孔关闭过程

Ca^(2+) Acts Upstream of H_2O_2 in Mediating H_2S-Induced Stomatal Closure in Arabidopsis thaliana

以拟南芥为材料,利用药理学实验,结合分光光度法和激光共聚焦显微技术,研究了Ca2+在硫化氢(H2S)诱导拟南芥气孔关闭过程中的作用及其与过氧化氢(H2O2)的关系。结果表明:H2S诱导气孔关闭,Ca2+螯合剂EGTA和质膜Ca2+通道阻断剂硝苯地平(Nif)能不同程度抑制H2S诱导的气孔关闭,而内质网钙泵阻断剂毒胡萝卜素(Thaps)对H2S的作用无显著影响。由此推测,Ca2+参与调节H2S诱导的拟南芥气孔关闭过程,且胞质中Ca2+来源于胞外Ca2+的内流。另外,H2S诱导拟南芥叶片NADPH氧化酶基因At RBOHD和At RBOHF以及细胞壁过氧化物酶基因At PRX34表达增强,促进叶片和保卫细胞中H2O2积累,EGTA对此起抑制作用,而外源Ca Cl2处理上调At RBOHD、At RBOHF和At PRX34的表达。表明Ca2+可能位于H2O2上游参与H2S诱导的拟南芥气孔关闭过程。

Using Arabidopsis thaliana as material, the effects of Ca2＋ in hydrogen sulphide（H2S）-induced guard cell movement and its relationship with hydrogen peroxide（H2O2） were investigated through pharmacological test combined with spectrophotography and confocal laser scanning microscopy techniques. The results showed that sodium hydrosulfide（Na HS）, a donor of H2 S, caused stomatal closure, and this inductive effects were weakened by addition of Ca2＋ chelator ethylene glycol-bis-（2-aminoethylether）-N,N,N＇,N＇-tetraacetic acid（EGTA） and plasma membrane Ca2＋ channel blocker nifedipine（Nif）, respectively, however, endoplasmic reticulum calcium pump blocker thapsigargin（ Thaps） had no signifi cant effect on stomatal movement induced by H2 S. These observations suggest that Ca2＋ participates in H2S-induced stomatal closure, [Ca2＋]cyt elevation in response to H2 S is mainly due to calcium infl ux across the plasma membrane. In addition, H2 S up-regulated the expression of NADPH oxidase genes At RBOHD, At RBOHF as well as cell wall peroxidase gene At PRX34, prompted H2O2 accumulation in leaves and guard cells, while EGTA inhibited these effects of H2 S. On the other hand, exogenous Ca Cl2 promoted the expression of At RBOHD, At RBOHF and At PRX34. Based on above results, it can be concluded that Ca2＋ acts upstream of H2O2 in mediating H2S-induced stomatal closure in A. thaliana.