Exploring anatomical controls of C4 leaf photosynthesis using a 3D reaction-diffusion model
C4 plants such as maize (Zea mays L.), sugarcane (Saccharum officinarum L.) and sorghum [Sorghum bicolor (L.) Moench.] photosynthesize at a high rate due to a CO2 concentration mechanism (CCM) that accumulates CO2 to saturating concentrations around the carboxylation site of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Transport of CO2 inside a leaf and, therefore, the CCM, is affected by leaf microstructure. Gas transport models with a realistic leaf microstructure help to assess the significance of anatomical features of C4 plants quantitatively for effective CCM. One- and two-dimensional gas transport models, when applied to analyze the gas diffusion in leaves, understate the three-dimensional nature. Here, we present the first 3D reaction-diffusion model for photosynthesis of a C4 leaf. Equations of CO2 transport and bicarbonate diffusion combined with a biochemical model of C4 photosynthesis were discretized over the 3D geometry of a maize leaf tissue. The model could describe the trends in responses of photosynthesis to light and CO2. The CO2 profile in the leaf microstructure was highly heterogeneous. The model suggests that rapid diffusion of CO2 to mesophyll cytosol is essential to achieve a high rate of photosynthesis.
Retta, M.A., Ho, Q.T., Yin, Xinyou, Verboven, P., Berghuijs, H.N.C., Struik, P.C. and Nicolai, B.M. (2017). Exploring anatomical controls of C4 leaf photosynthesis using a 3D reaction-diffusion model. Acta Hortic. 1154, 171-178
CO2 concentration mechanism gas exchange, biophysical model, computer simulation, leaf microstructure