Updating the steady-state model of C4 photosynthesis

C-4 plants play a key role in world agriculture. For example, C-4 crops such as maize and sorghum are major contributors to food production in both developed and developing countries, and the C-4 grasses sugarcane, miscanthus, and switchgrass are major plant sources of bioenergy. In the challenge to manipulate and enhance C-4 photosynthesis, steady-state models of leaf photosynthesis provide an important tool for gas exchange analysis and thought experiments that can explore photosynthetic pathway changes. Here a previous C-4 photosynthetic model developed by von Caemmerer and Furbank has been updated with new kinetic parameterization and temperature dependencies added. The parameterization was derived from experiments on the C-4 monocot, Setaria viridis, which for the first time provides a cohesive parameterization. Mesophyll conductance and its temperature dependence have also been included, as this is an important step in the quantitative correlation between the initial slope of the CO2 response curve of CO2 assimilation and in vitro phosphoenolpyruvate carboxylase activity. Furthermore, the equations for chloroplast electron transport have been updated to include cyclic electron transport flow, and equations have been added to calculate the electron transport rate from measured CO2 assimilation rates.

Automated summary

C-4 plants play a vital role in global agriculture, with crops like maize and sorghum being major contributors to food production, and grasses like sugarcane, miscanthus, and switchgrass serving as important sources of bioenergy. The temperature and kinetic parameters play critical roles in C-4 photosynthesis, influencing the efficiency of photosynthesis and gas exchange.