Effects of Salt Stress on the Activity and the Amount of Tonoplast H^+-ATPase from Pea Roots

盐胁迫对豌豆根液泡膜H^+-ATPase活性及含量的影响(英文)

To study the function and adaptive mechanism of tonoplast H + ATPase under salt stress, pea ( Pisum sativum L.) seedlings were treated with different concentrations of salt (100-250 mmol/L NaCl) and with 100 mmol/L NaCl for different days (1-3 d). The ATP hydrolytic activity and the proton transport activity and the changes of the amount of tonoplast H + ATPase (subunit A) were measured. ATP hydrolytic activity of H + ATPase prepared from plants treated with 250 mmol/L NaCl was reduced by about 25% compared to that of control plants, but that of stressed plants treated with 100 mmol/L and 200 mmol/L NaCl was unchanged. The activity from plants treated with 100 mmol/L NaCl for up to 3 d was lower than that of control plants by 20%. But the proton transport activity was increased under the same salt stresses as above. These results showed that the changes of the hydrolytic activity and the proton transport activity were not in proportion and salt stress may cause the change of the coupling ratio of H + transport activity to ATP hydrolysis. The protein amount kept unchanged and reduced a little only when pea was treated with 100 mmol/L NaCl for 3 d. These results indicated that salinity stimulated the increase of the pump efficiency of the V_ATPase from pea roots, which was due to the change of the coupling ratio, but not due to the increase of ATP hydrolysis and the amount of V_ATPase.

为了阐明液泡膜H+ ATPase在盐胁迫下的作用和适应性调节机制 ,对豌豆 (PisumsativumL .)植株进行不同盐浓度和不同盐胁迫时间 (1～ 3d)的处理后 ,分别测定液泡膜H+ ATPase的H+ 转运活性、水解活性和蛋白含量 (A亚基 )的变化。结果表明 ,10 0mmol/L和 2 0 0mmol/LNaCl处理 1dH+ ATPase的水解活性没有变化 ,而 2 5 0mmol/LNaCl处理 1d引起水解活性降低约 2 5 %。 10 0mmol/LNaCl处理 2d内水解活性没有变化 ,而第 3天活性下降约2 0 %。但是上述盐胁迫均能提高液泡膜H+ ATPase的质子转运活性 ,说明盐胁迫后H+ ATPase的水解活性和质子转运活性的变化不成比例 ,盐胁迫可能导致偶联比率的改变。Westernblot研究发现 ,上述盐胁迫对液泡膜H+ ATPase(A亚基 )的含量基本无影响 ,仅 10 0mmol/LNaCl处理 3d后A亚基的量略有下降。这些结果证明 ,盐胁迫能刺激提高豌豆根液泡膜H+ ATPase的H+ 泵效率 ,且泵效率的提高是源于偶联比率的改变 ,而不是由于ATP水解活性的提高和蛋白含量的增加。