Mechanism study on the origin of delayed fluorescence by an analytic modeling of the electronic reflux for photosynthetic electron transport chain

A mathematical–physical analysis model, which describes individually the electronic reflux of several significant components in the photosynthesis electron transport chain, was firstly developed. The process of electrons flowing back to the oxidized reaction center P680+ was simulated by a series of photochemical reaction equations, resulting in getting the linked differential equations of delayed fluorescence (DF) intensity. MATLAB provided a computationally efficient method to solve these linked equations. Simulations based on this model showed that the decay kinetics of DF accord with double exponential. DF components decaying in the millisecond range (fast phase) are related to the charge recombination of P680+ and QA-. The components decaying in the seconds range are associated with the recombination of P680+ with QB2-. The developed model was tested in maize leaves treated with different electron blockers to induce changes in photosynthesis electron transport chain. The experimental results demonstrated that the developed model can accurately determine the regulatory effects of electron blockers on photosynthesis electron transport chain. Therefore, the model presented here could be potentially useful for studying the electron transfer in plant. It also provides an experimental workbench for testing hypotheses as to the underlying mechanism controlling the change for different phases of DF.