Modelling the emergence of CAM photosynthesis in a stoichiometric model of leaf metabolism in different environments
In our recent publication with the Sweetlove group (https://www.plants.ox.ac.uk/people/lee-sweetlove) we studied the emergence of CAM photosynthesis by applying water-saving constraints to a stoichiometric model of leaf metabolism in different environments. Some of our main findings include: (i) The vacuolar storage capacity is a major determinant of the extent of the CAM cycle. To run the CAM cycle in C3 plants larger cells with larger vacuoles are needed. (ii) Depending on the environment, variants to the CAM cycle emerge. One involves simultaneous night-time CO2-fixation by PEP-carboxylase and isocitrate dehydrogenase (working backwards). This flux route is more efficient overall. (iii) The ICDH route involves accumulation of malate and (iso-)citrate at night and of proline during the day. This can explain diel fluctations of proline seen in ice plant following induction of CAM. Read more here: www.plantcell.org/content/32/12/3689.