The plasma membrane H+-ATPase is related to the development of salicylic acid-induced thermotolerance in pea leaves.

The plasma membrane H(+)-ATPase (PM H(+)-ATPase, EC.3.6.1.35) plays a key role in the plant response to environmental stress. In this study, a possible mechanistic link between the PM H(+)-ATPase and salicylic acid (SA)-induced thermotolerance was investigated in pea (Pisum sativum L. cv. NingXia) leaves. The burst of free SA in response to heat acclimation (38 +/- 0.5 degrees C) was observed, and peaks appeared subsequently both in activity and amount of PM H(+)-ATPase in pea leaves during heat acclimation. Similarly, exogenous SA also triggered the two peaks in the room temperature (25 +/- 0.5 degrees C). Paclobutrazol (PAC) was employed to infiltrate onto pea leaves prior to heat acclimation treatment. The results showed that the peaks of both free SA and activity of PM H(+)-ATPase still occurred after the PAC pretreatment. In acquired thermotolerance assessment (malondialdehyde content and degree of wilting), spraying SA and fusicoccin (FC, the activator of PM H(+)-ATPase) separately could protect pea leaves from heat injury. Results from RT-PCR and western blotting analysis indicated that the increase in activity of the PM H(+)-ATPase was due to its transcriptional and translational regulation. The subcellular localizations of PM H(+)-ATPase after the FC or SA pretreatment also showed that the PM H(+)-ATPase is important to maintain the integrity of plasma membrane against the heat stress. Taken together, these results suggest PM H(+)-ATPase is related to the development of SA-induced thermotolerance in pea leaves.