盐胁迫下无花果细胞质膜和液泡膜H^+-ATPase活性对脯氨酸积累的影响

The Roles of the Activities of Plasmalemma and Tonoplast H^+-ATPase on Salt induced Proline Accumulation of Ficus carica Cells

盐胁迫降低无花果振荡培养细胞培养液pH ,添加质膜H+ ATPase活性抑制剂Na3VO4 则抑制盐诱导的培养液pH下降 ,表明盐诱导培养液pH下降主要是细胞质膜H+ ATPase活性增加的结果。NaCl处理提高活体细胞质膜H+ ATPase活性 ,而降低膜微囊H+ ATPase活性。培养液中添加Na3VO4 5 0 μmol/L完全抑制盐胁迫下无花果细胞游离脯氨酸积累 ,但添加更高浓度Na3VO4 ,则提高细胞液泡膜H+ ATPase活性 ,同时Na3VO4 抑制脯氨酸积累的效应下降 ,暗示盐胁迫下无花果细胞质膜和液泡膜H+ ATPase共同参与细胞质pH调节 ,影响游离脯氨酸积累。

Salt stress significantly decreased the pH values of the medium in rotated culture of Ficus carica cells (Fig.1), which could be inhibited by the addition of Na 3VO 4, an inhibitor of plasma membrane H + ATPase (Fig.2), suggesting that salt induced pH decrease is through the activation of plasma membrane H + ATPase. NaCl treatment promoted the plasma membrane H + ATPase activity of Ficus carica cells (Fig.3), but inhibited the plasma membrane vesicle H + ATPase activity (Fig.4). Na 3VO 4 completely inhibited salt induced proline accumulation at a concentration of 50 μmol/L, but to a lesser degree at higher concentrations (Fig.5), implying that there is no simple direct relationship between the accumulation of proline and plasmalemma H + ATPase activity. Na 3VO 4 at higher concentrations also promoted tonoplast H + ATPase activity (Fig.6), implying that the loss of plasma membrane H + ATPase caused by Na 3VO 4 was offset by promotion of the tonoplast H + ATPase activity, which increased cytosol pH and thereby promoted proline accumulation. High pH of cultural medium, probably favoring the pumping out of H + from cytosol, promoted proline accumulation under salt or no salt treatment (Fig.7). Thus the synergism of plasma membrane H + ATPase and tonoplast H + ATPase increased the pH of cytosol which might be an important factor in regulating proline biosynthesis under salt stress.