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

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

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。

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.