NaCl胁迫对高粱根、叶鞘和叶片液泡膜ATP酶和焦磷酸酶活性的影响

NaCl胁迫初期 ,Na 主要在根和叶鞘中积累。相应地 ,根和叶鞘液泡膜ATP酶和焦磷酸酶水解活性、依赖ATP和PPi的质子泵活性及Na /H 逆向转运活性均明显增加 ,根和叶鞘的生长没有受到抑制。NaCl胁迫后期 ,Na 开始向地上部分运输并在叶片中积累。此时 ,叶片液泡膜质子泵和Na /H 逆向转运活性开始增加 ,根和叶鞘的Na/K比增加 ,其液泡膜ATP酶和焦磷酸酶水解活性、质子泵活性和Na /H 逆向转运活性下降。相应地 ,根和叶鞘的生长也下降。当保温介质中Na/K比超过 1时 ,液泡膜微囊ATP酶和焦磷酸酶活性均随Na/K比的增加而下降。表明非盐生植物液泡膜质子泵在盐胁迫的初期对Na 在液泡内的积累及其耐盐性起重要作用

Effects of NaCl Stress on the Tonoplast ATPase and PPase Activity in Roots, Sheaths and Blades of Sorghum Seedllings

During the early period of NaCl stress, Na accumulated mainly in roots and sheaths(Table 1). Correspondingly, the tonolast ATPase and PPase hydrolysis activity(Fig. 1), ATP and PPi dependent proton pump activity and Na /H antiport activity in roots and sheaths increased significantly(Figs.2,3), but root and sheath growth was not inhibited(Table 1). During the later period of NaCl stress, Na began to be transported to the shoots and accumulated in the blades(Table 1). At this time, proton pump activity and Na /H antiport activity in the blades also began to increase(Figs.2,3), ratio of Na/K of the roots and sheaths increased(Table 1) and their tonoplast ATPase and PPase hydrolysis activity(Fig.1), tonoplast proton pump activity and Na /H antiport activity decreased(Figs.2,3). Correspondingly, root and sheath growth was reduced(Table 1). ATPase and PPase activities of the tonoplast vesicles decreased as the Na/K ratio in the reaction medium rose to higher than 1(Figs.4,5). These results indicated that the tonoplast proton pump activity of nonhalophyte plays an important role in Na accumulation in vacuoles and salt tolerance during the early period of salt stress.