Though being a complex system, the Calvin cycle seems evolved to stay in only one or few steady state

Xinguang Zhu, Department of Physiological Molecular Plant Biology, University of Illinois Urbana-Champaign

Most current photosynthesis research implicitly assumes that photosynthesis occurs at only one steady state. However, since the rate of each reaction in photosynthesis depend nonlinearly on its substrate and product concentrations; the photosynthesis may have multiple steady states under a given environmental condition. Study about possibility of photosynthesis staying in multiple steady states is not available. As a firsts step towards characterizing all potential steady states of photosynthesis, we developed a Perl program, to identify number of steady states for dynamical systems using numerical program POLSYS_PLP (Wise et al 2000, ACM transaction on mathematical software). Using a simplified model of the Calvin cycle and the root finding programs, we find that that although 40 steady states were identified for the Calvin cycle, only one of them is physiologically feasible. Our results were discussed from an evolutionary perspective.