3. Results
To distinguish dark and light-mediated metabolic changes in guard cells,
we performed a 13C-HCO3 labelling
experiment. Guard cells were harvested pre-dawn and subjected to 0, 10,
20 and 60 minutes of continuous darkness or following transfer to white
light conditions (400 µmol photons m-2s-1). Primary metabolites were identified and used to
compare the changes at both metabolite content and13C-enrichment. Whilst changes in the content of
metabolites indicate alterations in the pool of them throughout the
experiment, the 13C-enrichment analysis demonstrates
the 13C distribution derived from CO2assimilation mediated by PEPc in the dark and by both PEPc and RuBisCO
in the light.