Dynamics and mechanisms of oscillatory photosynthesis

摘要

We classify mathematical models that can be used to describe photosynthetic oscillations using ideas from nonlinear dynamics, and discuss potential mechanisms for photosynthetic oscillations in the context of this classification. We then turn our attention to recent experiments with leaves transferred to a low CO_2 atmosphere which revealed stochastic oscillations with a period of a few seconds. Rubisco is the enzyme that takes both CO_2 and O_2 as substrates correspondingly for photosynthetic assimilation and for photorespiration. Photosynthesis depletes CO_2 and produces O_2 while respiration and photorespiration work in the opposite direction, so the product of one process becomes the reactant of the other coupled process. We examine the possibility of oscillations of CO_2 and O_2 in the leaf in relation to photorespiration. We suggest that in the cell, oscillations with a period of a few seconds, corresponding to the time between photosynthetic CO_2 fixation and photorespiratory CO_2 release, underlie the dynamics of metabolism in C_3 plants.