Development of Two-Dimensional Model of Photosynthesis in Plant Leaves and Analysis of Induction of Spatial Heterogeneity of CO Assimilation Rate under Action of Excess Light and Drought.

Photosynthesis is a key process in plants that can be strongly affected by the actions of environmental stressors. The stressor-induced photosynthetic responses are based on numerous and interacted processes that can restrict their experimental investigation. The development of mathematical models of photosynthetic processes is an important way of investigating these responses. Our work was devoted to the development of a two-dimensional model of photosynthesis in plant leaves that was based on the Farquhar-von Caemmerer-Berry model of CO assimilation and descriptions of other processes including the stomatal and transmembrane CO fluxes, lateral CO and HCO fluxes, transmembrane and lateral transport of H and K, interaction of these ions with buffers in the apoplast and cytoplasm, light-dependent regulation of H-ATPase in the plasma membrane, etc. Verification of the model showed that the simulated light dependences of the CO assimilation rate were similar to the experimental ones and dependences of the CO assimilation rate of an average leaf CO conductance were also similar to the experimental dependences. An analysis of the model showed that a spatial heterogeneity of the CO assimilation rate on a leaf surface should be stimulated under an increase in light intensity and a decrease in the stomatal CO conductance or quantity of the open stomata; this prediction was supported by the experimental verification. Results of the work can be the basis of the development of new methods of the remote sensing of the influence of abiotic stressors (at least, excess light and drought) on plants.