Table 2.
Distinctive features of FBA-based models addressing carbon flux re-distribution in CAM.
| Model | Modified from | Focus | Modifications from previous models | Additional constraints |
|---|---|---|---|---|
| Cheung et al., 2014 | Cheung et al., 2013 | Interaction between day and night phase of metabolism | Coupled two identical genome-wide models representing either day or night and modeled as a single optimization problem. Implemented different constraints at each phase. Each phase was given the choice of accumulating sucrose and amino acids. Compared C3 with CAM scenarios |
No CO2 uptake during the night for the CAM scenario. Ratio of sucrose and amino acid export to the phloem: 3:1 (day:night) Ratio of nitrogen import from the xylem into the leaf: 3:2 (day:night) Amino acids could only accumulate during the day |
| Shameer et al., 2018 | Cheung et al., 2014 | Calculating energetic costs for C3 and CAM | Reduced the model to a core stoichiometric model of central plant metabolism (641 reactions and 555 metabolites) Considered explicitly organellar pH and charge state of metabolites |
Phloem export according to tomato phloem sap content for the C3 scenario. Phloem export according to O. ficus-indica phloem sap content for the CAM scenario. |
| Töpfer et al., 2020 | Shameer et al., 2018 | CAM interaction with the environment | Divided the two-phase diel model into a 24-phase model. Added a simplified gas diffusion to test the model under measured relative humidity and temperature Tested different malate storage capacities. Implemented Pareto frontier analysis to evaluate CO2 demand and water saving tradeoff |
Unconstrained CO2 uptake for both scenarios C3 average vacuolar capacity for C3 scenario K. daigremontiana vacuolar capacity or unrestricted vacuolar capacity for CAM scenario |
| Tay et al., 2021 | Shameer et al., 2018 | CAM cycling, CAM idling and C3-CAM evolution | Considered that O2 could accumulate and be transferred to the next phase. Made a series of models gradually decreasing gas exchange |
Phloem export, O2 and CO2 exchange set to zero for CAM idling scenario. O2 and CO2 exchange set to zero during the day phase for CAM cycling scenario. O2 and CO2 exchange constrained to different values between 13.12 and 0 μM m−2 s−1 for the series with decreased gas exchange |