Fig 2. CO₂ assimilation rates (A) predicted by the C4 photosynthesis model of [15], solid lines, and the present nonlinear genome-scale model (markers) maximizing CO₂ assimilation with equivalent parameters.

The nonlinear model incorporates the mesophyll CO₂ level as a parameter through the constraints in Eqs 5, 6 and 7. Left, A vs mesophyll CO₂ levels with varying PEPC levels (top to bottom, v_p,max = 110, 90, 70, 50, and 30 μmol m^-2 s^-1). Right, A vs total maximum activity of all bundle sheath decarboxylase enzymes (equivalent to the maximum PEP regeneration rate V_pr in [15]) at varying Rubisco levels (top to bottom, v_c,max = 70, 60, 50, 40, and 30 μmol m^-2 s^-1). Other parameters as in Table 4.1 of [15], except with nonphotorespiratory respiration rates r_d = r_m = 0.