Respiratory acclimation in Arabidopsis thaliana leaves at low temperature

Acclimation of 25 degreesC-grown Arabidopsis thaliana at 5 degreesC resulted in a marked increase of leaf respiration in darkness (R-d) measured at 5 degreesC. R-d was particularly high in leaves developed at 5 degreesC. Leaf respiration (non-photorespiratory intracellular decarboxylation) in the light (R-l) also increased during cold acclimation, but less so than did R-d. The ratio R-d/P-t (P-t - true photosynthesis) was higher in more acclimated or cold-developed leaves, while the ratio R-l/P-t remained unchanged. In cold-acclimated leaves, R-l did not correlate with 3-phosphoglycerate and pyruvate nor with hexose phosphate pools in the cytosol. R-l in A. thaliana leaves was probably not limited by the substrate during cold acclimation. Under the conditions tested, R-d was more sensitive to low temperature stress than R-l.