Photosynthesis is especially sensitive to environmental conditions and
the composition of the photosynthetic apparatus can be modulated in
response to environmental change, a process termed photosynthetic
acclimation. Previously, we identified a role for a cytosolic fumarase,
FUM2 in acclimation to low temperature in Arabidopsis thaliana. Mutant
lines lacking FUM2 were unable to acclimate their photosynthetic
apparatus to cold. Here, using gas exchange measurements and metabolite
assays of acclimating and non-acclimating plants, we show that
acclimation to low temperature results in a change in the distribution
of photosynthetically fixed carbon to different storage pools during the
day. Proteomic analysis of wild-type Col-0 Arabidopsis and of a fum2
mutant which was unable to acclimate to cold indicates that extensive
changes occurring in response to cold are affected in the mutant.
Metabolic and proteomic data were used to parameterise metabolic models.
Using an approach called flux sampling, we show how the relative export
of triose phosphate and 3-phsphoglycerate provides a signal of the
chloroplast redox state that could underly photosynthetic acclimation to
cold.