Temperature dependence of intracellular pH in higher plant cells

The recent introduction of ³¹P nuclear magnetic resonance spectroscopy offers a new approach to the problem of obtaining a simultaneous and direct evaluation of both the cytoplasmic and vacuolar pH in higher plant cells (J. K. M. Roberts, P.M. Ray, N. Waderlardetzky and O. Sardetzky, 1980, Nature 283, 870–872; 1981, Planta 152, 74–78). Using this method we have been able to detect a selective pH decrease of about 0.5 units at the level of the cytoplasmic compartment of maize root tips when the temperature was increased from 4 to 28°C. This effect was completely reversible with temperature. No pH variation could be detected at the level of the vacuolar compartment.