Effect of Temperature on Electron Transport Activities of Isolated Chloroplasts

Temperature-induced changes in electron transport activities of chloroplasts isolated from chilling-sensitive and chilling-resistant plants have been examined. Using methylviologen as electron acceptor, temperature-induced changes occurred in the photosystem II plus photosystem I activities of chloroplasts isolated from chilling-resistant spinach (Spinacia oleracea L.) and pea (Pisum sativum L. cv. Alaska) plants. The changes occurred at approximately 17 C for spinach and 15 C for pea. A temperature-induced change, at approximately 13 C, in photosystem I activity using methylviologen was also observed for pea chloroplasts. These results extend earlier work and indicate that temperature has a general effect on the functioning of thylakoid membranes.Chloroplasts isolated from chilling-sensitive bean plants (Phaseolus vulgaris L. cv. Blue Lake 141) show a temperature-induced change in ferricyanide reduction at approximately 12 C. These results with spinach, pea, and bean support the view that the presence of temperature-induced changes in chloroplast activity assayed in vitro is not correlated with chilling sensitivity.