Figure 1.

A general scheme of the developed two-dimensional model (a) and main processes described by the model on the cell level (b). Model elements (squares) include both mesophyll cells and stomata or only mesophyll cells (without stomata). Small arrows in the general scheme show transport of carbon dioxide, H⁺, and K⁺ between apoplastic volumes of neighboring cells and across the plasma membrane. PAR is the photosynthetic active radiation. pH_ap, pH_cyt, and pH_str are pH in the apoplast, cytoplasm, and stroma of chloroplasts, respectively. B_cyt⁻ and B_cytH are the free and proton-bound cytoplasmic buffers. B_ap⁻, B_apH, and B_apK are the free, proton-bound, and potassium-bound apoplastic buffers. E_m is the difference of electrical potentials across the plasma membrane. FvCB model is the Farquhar–von Caemmerer–Berry model. The main systems of ion transport at rest, including H⁺-ATP-ases, H⁺/K⁺-antiporters, inwardly rectifying K⁺ channels, and outwardly rectifying K⁺ channels, are described in the two-dimensional photosynthetic model.