H2O2介导的H2S产生参与干旱诱导的拟南芥气孔关闭

以野生型拟南芥(Arabidopsis thaliana)及其突变体(atrbohD、atrbohF、atrbohD/F、atl-cdes、atd-cdes)和过表达株系(OEL-CDes、OED-CDes)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, 探讨硫化氢(hydrogen sulfide, H₂S)在干旱诱导的拟南芥气孔关闭中的作用及其与过氧化氢(hydrogen peroxide, H₂O₂)的关系。结果表明, H₂S清除剂次牛磺酸(hypotaurine, HT)及合成抑制剂氨氧基乙酸(aminooxy acetic acid, AOA)、羟胺(hydroxylamine, NH₂OH)和丙酮酸钾(potasium pyruvate, C₃H₃KO₃)+氨水(ammonia, NH₃)均可不同程度抑制干旱诱导的气孔关闭; 干旱对OEL-CDes和OED-CDes植株气孔关闭的诱导作用明显, 而atl-cdes和atd-cdes叶片气孔对干旱胁迫反应的敏感性下降; 干旱胁迫能明显增加拟南芥保卫细胞中H₂O₂水平及叶片中H₂S含量, 提高D-/L-半胱氨酸脱巯基酶活性及基因表达量, 而对突变体atrbohD、atrbohF和atrbohD/F没有显著影响。清除H₂O₂可减弱干旱胁迫对H₂S含量和D-/L-半胱氨酸脱巯基酶活性的诱导效应。研究结果表明H₂S位于H₂O₂下游参与干旱诱导拟南芥气孔关闭的信号转导过程。

H2S Induced by H2O2 Mediates Drought-induced Stomatal Closure in Arabidopsis thaliana

Using the Arabidopsis thaliana wild-type; mutants atrbohD, atrbohF, atrbohD/F, atl-cdes, and atd-cdes; and D-/L-cysteine desulfhydrase overexpression plants, we investigated the roles of hydrogen sulfide (H2S) in drought-in- duced stomatal closure in A. thaliana. We used a pharmacological experiment combined with laser scanning confocal microscopy and spectrophotography. The H2S scavenger hypotaurine and H2S synthesis inhibitors aminooxy acetic acid, hydroxylamine, potasium pyruvate and ammonia all inhibited drought-induced stomatal closure. Drought-induced stomatal closure was greater in overexpression than wild-type plants, with the effect not obvious in atl-cdes and atd-cdes. Moreover, drought stress enhanced the level of hydrogen peroxide (H2O2) in guard cells and increased the content of H2S and the activity and expression of D-/L-cysteine desulfhydrase in leaves but had no significant effect in atrbohD, atrbohF, and atrbohD/F. The H2O2 scavenger decreased drought-induced H2S production and the activity of D-/L-cysteine desulf-hydrase in leaves. H2S may function downstream of H2O2 in the signal transduction pathway of drought-induced stomatal closure in A. thaliana.