Theoretical Analysis of the Influence of Fluctuations in the Activityof the Plasma Membrane H<sup>+</sup>-ATPase on Low-Temperature-Induced Electrical Responses in a Plant Cell
Fluctuations in physiological processes are an important property of biosystems; these fluctuations can play both positive and negative roles in living organisms. In particular, fluctuations in the activity of ion channels can increase sensitivity of the receptors and modify the activity of neural networks. A potential influence of fluctuations on the electrical activity in plants has not been yet investigated. The aim of this work was a theoretical analysis of the influence of fluctuations in the plasma membrane H+-ATPase activity on the low-temperature-induced electrical responses in the plant cell. We used our earlier model of plant electrogenesis, which was modified by description of fluctuations in the H+-ATPase activity. Fluctuations in the H+-ATPase activity were described by multiplying the H+ flux through the H+-ATPase by an additional random value with a normal distribution (the value was recalculated every 1 s; the averaged value was 1). The analysis of the model showed that an increase in the magnitude of fluctuations in the H+-ATPase activity was connected with: (i) a non-linear increase of fluctuations in the membrane potential at rest (without stimulation); (ii) a decrease in the threshold of generation of simulated action potential in single cells; (iii) modification of low-temperature-induced changes in the membrane potential averaging over a large quantity of cells. Our results theoretically predict that fluctuations in the H+-ATPase activity can decrease the threshold of generation of electrical responses in a plant cell upon cooling.