Effects of growth temperature on photosynthetic carbon metabolism in green plants II. Photsoynthetic14CO2-incorporation in plants acclimatized to varied temperatures1

摘要

During photosynthetic14CO2-fixation, leaves of plants such as wheat, the broad bean and spinach, which had been acclimatized to high temperature (20–25°C), incorporated much more radioactivity into sucrose, and less into glycine and serine in comparison with similar plants grown in the cold (mean temperature, 5–7°C).Radioactivities incorporated into glycine and serine greatly descreased on the addition ofα-hydroxyethylsulfonate or on the removal of oxygen from the atmosphere, indicating that these compounds are synthesized through the glycolate pathway.In leaves of wheat grown under low temperatures, relatively high radioactivity was detected in ribulose 1,5-diphosphate among the photosynthetic14CO2-fixation products, whereas practically no radioactivity was detected in this compound in leaves of wheat which had been acclimatized to high temperatures. We assumed that the carboxylation reaction of ribulose 1,5-diphosphate is suppressed in plants acclimatized to low temperatures.It was further inferred that the C-2 and C-2 moiety of ribulose 1,5-diphosphate accumulating as a result of suppression of carboxylation is converted to glycine and serine through the glycolate pathway.The possibility was also discussed that during photosynthetic CO2-fixation in wheat leaves at least a part of the C6-compound formed by the carboxylation of ribulose 1,5-diphosphate is directly converted to sugar pho