Partial cloning, characterization, and analysis of expression and activity of plasma membrane H+-ATPase in Kallar grass [Leptochloa fusca (L.) Kunth] under salt stress.

Kallar grass (Leptochloa fusca) is a highly salt-tolerant C4 perennial halophytic forage. The regulation of ion movement across the plasma membrane (PM) to improve salinity tolerance of plant is thought to be accomplished with the aid of the proton electrochemical gradient generated by PM H+-ATPase. In this study, we cloned a partial gene sequence of the Lf PM H+-ATPase and investigated its expression and activity under salt stress. The amino acid sequence of the isolated region of Lf PM H+-ATPase possesses the maximum identity up to 96% to its ortholog in Aeluropus littoralis. The isolated fragment of Lf PM H+-ATPase gene is a member of the subfamily Π of plant PM H+-ATPase and is most closely related to the Oryza sativa gene OSA7. The transcript level and activity of the PM H+-ATPase were increased in roots and shoots in response to NaCl and were peaked at 450 mM NaCl in both tissues. The induction of activity and gene expression of PM H+-ATPase in roots and shoots of Kallar grass under salinity indicate the necessity for this pump in these organs during salinity adaptation to establish and maintain the electrochemical gradient across the PM of the cells for adjusting ion homeostasis.