Limitations in carbon metabolism and photosynthesis leads to increased reduction state in chloroplasts of Arabidopsis thaliana

Abstract

Upon low temperature stress we observe an increased reduction state (measured as: a higher NADPH/NADP-ratio, an increased reduction of the intersystem pool size and an increased stromal electron pool size) in Arabidopsis thaliana. The increased reduction state of the chloroplast in the low temperature stressed plants is partly readjusted to the level seen in warm-grown plants upon low temperature acclimation. However, the low temperature acclimated plants still exhibit a higher absolute reduction than the warm grown control plants. An increased reduction state of chloroplast constituents can greatly influence the ongoing metabolic processes and a sustained higher reduction requires that the plant alter some metabolic processes. We are investigating different metabolic pathways capable of consuming part of the increase in reducing power. This shift in metabolic processes would allow the low temperature acclimated plant to sustain the productivity observed at warm temperatures. We are also looking at the function of the photosystems and electron transport upon low temperature stress and low temperature acclimation.