Our research is focused on understanding plant metabolism, mostly using stable isotopes (13C, 15N, 33S) and metabolomics. We use both natural isotope abundance and isotopic labelling to shed light on metabolic fluxes and interactions between metabolic pathways. Plant leaves have competing metabolisms occurring at the same time (photosynthesis, photorespiration, mitochondrial respiration, nitrogen and sulphur assimilation) but the means by which they are reconciled and orchestrated within plant cells is not well-documented. The results from our group provided evidence that:
- The tricarboxylic acid pathway ("Krebs cycle") is not cyclic in illuminated leaves.
- Leaf nitrogen assimilation in the light mostly utilises carbon reserves and not current photosynthates.
- Photorespiration stimulates sulphur assimilation.
- Anaplerotic fixation by phosphoenolpyruvate carboxylase is stimulated by photorespiratory conditions and not by high CO2 conditions.
- Leaf day respiration plays a role in the Kok effect but through specific malate metabolism that resembles the "light enhanced dark respiration" (LEDR phenomenon).
- The carbon allocation to major components (such as soluble sugars) is not proportional to net photosynthesis.
- ... and many other findings!
With no doubt, teaching is a pleasure when I see students marvel at biological mechanisms and adaptations, particularly in the field