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 have been examined. In the presence of N-methylphenazonium methosulfate, the thylakoids isolated from chilling-resistant barley (cv. Kanby) and pea (cv. Alaska) and chilling-sensitive mung bean (cv. Berken) plants showed temperature-induced changes at approximately 8.6, 13.3, and 14.0 C, respectively. Barley thylakoids assayed in the presence of sodium thiocyanate also showed a change at 8.6 C, whereas with no addition or upon the inclusion of both N-methylphenazonium methosulfate and sodium thiocyanate the change occurred at approximately 11.5 C.Temperature-induced changes in electron transport activities occurred at temperatures approximating those for proton efflux for each of the three plants. These results indicate that 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.