Phenotypic changes in the fluidity of the tonoplast membrane of crassulacean-acid-metabolism plants in response to temperature and salinity stress

摘要

Electron paramagnetic resonance-spectroscopic studies on spin-labeled purified tonoplast membranes showed that in the obligate crassulacean-acid-metabolism (CAM) plantKalanchoë daigremontianaHamet et Perr. the fluidity of the tonoplast decreased during acclimation to higher temperatures. This phenotypic change in tonoplast fluidity was paralleled by a decrease in the mobilization of malic acid from the vacuoles during CAM in the light. The shift from the C3to the CAM mode of photosynthesis in the facultative CAM plantMesembryanthemum crystallinumL. also led to a decrease in the fluidity of the tonoplast membrane. The results are consistent with the hypothesis that the ability to store malic acid during CAM in the vacuoles depends largely on the actual fluidity of the tonoplast membrane