Ca^(2+)参与硝普钠对干旱胁迫下小麦叶片NO水平的调控

Ca^(2+) Involved in Nitric Oxide Content of Wheat Leaves Induced by SNP under Drought Stress

研究干旱胁迫下外源一氧化氮(NO)供体硝普钠(SNP)处理对小麦幼苗叶片NO水平的影响及其与Ca2+的关系。在15%PEG-6000胁迫下测定NO含量和NO合成酶活性,结果表明,干旱胁迫下小麦幼苗叶片一氧化氮合酶(NOS)活性显著增加,且钙依赖型cNOS(CaM的组成型NOS)快速调控NO产生,但是随着胁迫时间的延长,不依赖钙iNOS(CaM的诱导型NOS)的活性在NOS活性比例缓慢增加,而硝酸还原酶(NR)产生NO的能力只占总NR提取物活性的很小一部分;0.1mmol/LSNP处理可显著提高干旱胁迫下小麦幼苗叶片NOS和NR活性,诱导NO水平提高,显著缓解膜脂过氧化;用质膜Ca2+通道抑制剂LaCl3与SNP共处理,显著减弱或抵消SNP促进NO合成作用。SNP显著提高干旱胁迫下小麦幼苗叶片NO合成酶活性和NO含量,有效缓解膜的氧化损伤,而Ca2+参与SNP对干旱胁迫下小麦幼苗叶片NO水平的调控。

The effects of sodium nitropprusside （SNP, an Ca^2＋ in wheat seedlings leaves were investigated under exogenous nitric oxide donor） on the relation NO and drought stress. It was included that on NO content and nitric oxide-synthesis enzyme activities under 15% PEG-6000 drought stress condition. The result showed that 15% PEG could apparently enhance NOS activity in wheat seedling, NO was quickly produced by cNOS, and the proportion of iNOS in NOS was increased slowly after 6 h treatments. NO was also induced by NR, which was a little part of total NR activity. The 0.1 mmol/L SNP treatment could apparently alleviate the drought-induced membrane lipid peroxidation, which consistent with the up-regulation of NOS, NR and NO. The effect of SNP was decreased after treatment of blocker of plasma membrane Ca^2＋ channels LaCl3. The above results indicated that exogenous nitric oxide donor （SNP） could apparently increase nitric oxide-synthesis enzyme activities and NO content, and Ca^2＋ was involved in regulation of NO level in wheat seedling leaves by SNP under drought stress.