Inducible expression of plasma membrane H+-ATPase in the roots of figleaf gourd plants under chilling root temperature

Figleaf gourd plants were grown under different root temperatures and the a cclimation process of the roots was investigated. Conditioning of the roots by a gradual decrease (2 degrees C h(-1)) in root temperature to 6 degrees C considerably lowered the electrolyte leakage of the plant leaves compare d to non-conditioned roots. A root temperature of 6 degrees C was critical for the increase in H+-ATPase (EC 3.6.1.35) activity in the plasma membrane s of the roots and this increase was abolished by the addition of cyclohexi mide in the root medium. The H+-transport rate of the plasma membranes was also increased by low root temperature. Increases in the amount of the plas ma membrane H+-ATPase gene transcription and translation in the plant roots under chilling root temperature were demonstrated by Northern and Western blot analysis, respectively. A correlation between the leaf temperature, me asured by an infra-red thermometer, and the H+-ATPase activity suggests the involvement of H+- ATPase in the root acclimation process.