Effect of Temperature on Proton Efflux from Isolated Chloroplast Thylakoids

Abstract

Temperature-induced changes in the decay of the light-induced proton gradient of chloroplast thylakoids isolated from chilling-resistant and chilling-sensitive plants were examined. In the presence of N-methylphenazonium methosulfate, the thylakoids isolated from chilling-resistant Hordeum vulgare cv. Kanby and Pisum sativum cv. Alaska and chilling-sensitive Vigna radiata cv. Berken showed temperature-induced changes at .apprx. 8.6, 13.3 and 14.0.degree. C, respectively. Barley thylakoids assayed in the presence of sodium thiocyanate also showed a change at 8.6.degree. C; with no addition or upon the inclusion of both N-methylphenazonium methosulfate and sodium thiocyanate the change occurred at .apprx. 11.5.degree. C. Temperature-induced changes in electron transport activities occurred at temperatures approximating those for proton efflux for each of the 3 plants. Temperature has a general effect on thylakoid membranes and that chloroplast thylakoids from chilling-resistant and chilling-sensitive plants have their proton permeability properties affected similarly by temperature.