Abstract

Changes in the growth response of mung bean hypocotyl were studied as a function of temperature and related to structural and functional changes in membranes. The temperature coefficient for growth increased abruptly below 28°C and again below 15°C. The Arrhenius activation energy of mitochondrial succinate oxidase also increased below these same temperatures. Changes in molecular ordering were detected in the membrane lipids of both mitochondria and chloroplasts at about 28 and 15°C by electron spin resonance spectroscopy. The results demonstrate a precise relationship between changes in the molecular ordering of membrane lipids and the physiological response of plants to changes in temperature.