Effect of Temperature on Electron Transport Activities of Isolated Chloroplasts

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Abstract
Temperature-induced changes in electron transport activities of chloroplasts isolated from chilling-sensitive and chilling-resistant plants were 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.degree. C for spinach and 15.degree. C for pea. A temperature-induced change, at approximately 13.degree. C, in photosystem I activity using methylviologen was also observed for pea chloroplasts. Temperature may have 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.degree. C. Apparently, the presence of temperature-induced changes in chloroplast activity assayed in vitro is not correlated with chilling sensitivity.