The origin of photosystem-I-mediated electron transport stimulation in heat-stressed chloroplasts

摘要

Exposure of isolated chloroplasts of pea (Pisum sativumL.) to temperatures above 35° C leads to a stimulation of photosystem-I-mediated electron transport from dichlorophenolindophenol to methyl viologen. The threshold temperature for this stimulation coincides closely with that for heat-induced inhibition of photosystem-II activity in such chloroplasts. This coincidence is explained in terms of a rearrangement of the thylakoid membrane resulting in the exposure of a new set of donor sites for dichlorophenolindophenol within the cytochromef/b6complex of the electron-transport chain linking the two photosystems