一氧化氮调节盐胁迫下小麦幼苗根部质膜H^＋-ATPase和焦磷酸酶活性提高耐盐性

采用外源一氧化氮(NO)供体硝普钠(SNP)研究了NO对盐胁迫下小麦(Triticum aestivum L.)幼苗耐盐性的影响。结果表明,0.1 mmol/L SNP处理显著缓解了150 mmol/L NaCl 胁迫对小麦幼苗生长的抑制效应,包括水分丧失以及叶绿素降解,从而提高了小麦幼苗的耐盐性。进一步结合1 mg/mL血红蛋白处理则显著逆转了SNP诱导的上述效应;利用亚硝酸钠和铁氰化钾作为对照也证实了NO对小麦幼苗耐盐性的专一性调节作用,并可能与NO对小麦幼苗根部质膜 H -ATPase和焦磷酸酶活性诱导有关。此外,尽管NO显著提高了盐胁迫下小麦幼苗根部细胞质膜H -ATPase和焦磷酸酶的ATP水解活性,但是对跨膜H 转运则没有明显影响。应用外源CaSO4 和 EGTA 处理也证实,Ca2 可能在NO诱导的质膜 H -ATPase和焦磷酸酶活性的提高过程中起信号作用。另外,分析盐胁迫下小麦幼苗根部 Na 和K 含量的变化也发现,NO对Na 含量没有明显影响,但是却显著提高了K 水平和K /Na 比,这可能也是NO提高小麦幼苗耐盐性的原因之一。

Nitric Oxide Modulates the Activities of Plasma Membrane H~ -ATPase and PPase in Wheat Seedling Roots and Promotes the Salt Tolerance Against Salt Stress

Effects of exogenous sodium nitroprusside (SNP), a nitric oxide (NO) donor, on the salttolerance of wheat (Triticum aestivum L.) seedlings indicated that NO donor significantly alleviated thegrowth inhibition, water loss and the decay of chlorophyll in wheat seedlings caused by 150 mmol/L NaClsalt stress, thus led to the promotion of salt tolerance against salt stress. Combined with 1 mg/mLhemoglobin treatment reverted the above SNP actions by restoring the growth of wheat seedlings andchlorophyll content to the level found in untreated wheat seedlings under salt stress. The specific role ofNO in regulating the salt tolerance of wheat seedlings under salt stress was confirmed by using NaNO2 andK3Fe(CN)6] as control. Further investigation showed that the effect of both which might be related to theinduction of plasma membrane H -ATPase and H -PPase (H -pyrophosphatase) activities by NO in the rootsof wheat seedling under salt stress. NO obviously enhanced the hydrolylic activities of H -ATPase and H -PPase, but did not affect the H transport ability across plasma membrane in wheat seedling roots undersalt stress. Treatment with exogenous CaSO4 and EGTA also showed that Ca2 was vital to the NO inducedactivities of H -ATPase and H -PPase respectively in the roots of wheat seedling under salt stress.Investigation of NO on the content of Na and K in the roots of wheat seedlings illustrated that NO did notobviously affect the content of Na , but significantly elevated the content of K as well as leading to theincrease the ratio of K to Na in the roots of wheat seedling under salinity conditions. This was alsoimportant to believe that NO induced the adaptive abilities of wheat seedlings against NaCl salt stress.