Effects of growth temperature on photosynthetic carbon metabolism in green plants III. Differences in structure, photosynthetic activities and activities of ribulose diphosphate carboxylase and glycolate oxidase in leaves of wheat grown under varied temperatures

The rate of ferricyanide photoreduction in broken chloroplastsisolated from leaves of wheat acclimatized to a low temperature(mean temperature, 5–7?C) was similar to that in chloroplastsfrom wheat acclimatized to a high temperature (20–25?C). There was no practical difference in glycolate oxidase activityin leaf extracts of wheat plants grown at low and high temperatures.In contrast, the ribulose diphosphate carboxylase activity ofchloroplasts from low temperature sample was less than halfthat for the high temperature sample. Chloroplasts having a high rate of photosynthetic CO₂-fixationwere obtained from wheat acclimatized to a low temperature,whereas the CO₂-fixation activity in chloroplasts isolated fromhigh temperature-acclimatized wheat was very low. Electron microscopy revealed that chloroplasts in high temperature-acclimatizedwheat were ellipsoidal, electron dense and contained starchgranules. Those in low temperature-acclimatized leaves wereround and did not contain starch granule. ²Present address: Department of Botany, Faculty of Science,University of Tokyo, Tokyo, Japan (Received August 7, 1973; )