Application of a Mathematical Model of Variation Potential for Analysis of Its Influence on Photosynthesis in Higher Plants

Local injuries induce generation of variation potential (VP) in higher plants; VP propagates into intact parts of a plant and induces the photosynthesis inactivation, which is probably connected with a proton influx into the cells. The aim of this work was to theoretically investigate participation of the intra-and extracellular pH changes in this process using the VP mathematical model developed earlier. The VP model took into account main systems of ion transport in a cell and their regulation; concentrations of the potential-forming ions; buffering properties, and the involvement of a wound substance in a signal propagation. To describe the dependence of the photosynthetic parameters on the pH changes, experimentally obtained linear relations were used. The model was shown to give a good qualitative description of the photosynthetic response at a distance of 10 cm from the injury area and simulated a considerable attenuation of the response at a distance of 22 cm. Analysis of the dependence of the photosynthetic response parameters on the VP amplitude also showed a qualitative correspondence of the model with the experimental results. Thus, experimental photosynthetic response is described well by the VP model that presumes linear dependencies of the photosynthetic parameter changes on pH shifts. This theoretical result supports a hypothesis about a key role of pH shifts in the development of the photosynthetic response.