Sensitivity of plasma membrane H+-ATPase of cucumber root system in response to low root temperature.

Cucumber plants (Cucumis sativus L.) were grown at different root temperatures and the H+-ATPase activities in the root plasma membranes were investigated. Electrolyte leakages and the amount of water transported from root to shoot indicated the sensitivity of cucumber root systems to low root temperature. The increase in H+-ATPase activity after 1 day of low root temperature treatment was reversed and gradually diminished as root temperatures of 10 °C continued for another 6 days. The H+-transport rate of the plasma membranes and the transcriptional activity of the corresponding gene expression closely followed the H+-ATPase activity. The role of H+-ATPase in root plasma membranes in terms of the root acclimation process at low root temperature is discussed.