The Bellasio 2019 model is a generalized C3 leaf-photosynthesis model, that includes simplified representations of the light and dark reactions and a stomatal behavior submodule. A lot of its implementation is based on past work by the same author and is mainly inspired by the common Farquhar-von Caemmerer-Berry model. The light reactions are modified from Yin et al. (2004) and include the potential rates of ATP and NADPH production based on light intensity. This model has been created with the simple user in mind, and the author has made an effort to show its simplicity, by giving access to a Microsoft Excel Workbook containing the entire model. To showcase the model's capabilities, the author creates common steady-state carbon assimilation curves, against intercellular CO₂ concentration and light intensity, and compares them to experimental data from the literature. As many models of photosynthesis rely on purely stead-state assumptions, this model is also validated in dynamic conditions, showing for example the response of the model to a fluctuation of ambient oxygen concentration.
This model was created to stay as simple as possible, while still being able to accurately represent the main features of C₃ photosynthesis. As such, it can be used as a base for more complex models, or as a starting block in larger models of plant physiology. While giving access to the entire model in an Excel Workbook format is transparent and great, the execution of said practice has been inefficient in this instance. The entire mathematical description of the model is also given in the Appendix of the publication, however there are missing or different equations between the publication and the Excel Workbook, which can lead to confusion. On top of that, the simulation protocols used for each figure are only given in small details, which leads to further confusion when trying to reproduce the results and see which equations are correct or not.
| Symbol | ID | Initial value |
|---|---|---|
| CO2 | ||
| HCO3 | 0.1327 | |
| RUBP | 2 | |
| PGA | 4 | |
| DHAP | 4 | |
| ATP_st | 0.68 | |
| NADPH_st | 0.21 | |
| RU5P | 0.34 | |
| Ract | 1 | |
| J_NADPH | 0.1 | |
| J_ATP | 0.16 | |
| Ci | ||
| gs | 0.334934046786077 |
| Symbol | ID | Value |
|---|---|---|
| AP_tot | 1.5 | |
| Pi_tot | 15 | |
| p_o2 | 210000 | |
| Kh_o2 | 833300 | |
| V_m | 0.03 | |
| PPFD | 1500 | |
| RLight | 0.001 | |
| s | 0.43 | |
| PhiPSII_LL | 0.72 | |
| PhiPSI_LL | 1 | |
| alpha_ppfd_PhiPSII | 0.00125 | |
| V0_ppfd_PhiPSII | -0.8 | |
| theta_ppfd_PhiPSII | 0.7 | |
| f_pseudocycNR | 0.01 | |
| fq | 1 | |
| f_ndh | 0 | |
| h | 4 | |
| Ca | 350 | |
| alpha_ppfd_rub | 0.0018 | |
| V0_ppfd_rub | 0.16 | |
| theta_ppfd_rub | 0.95 | |
| alpha_co2 | 400 | |
| V0_co2 | -0.2 | |
| theta_co2 | 0.98 | |
| tau_i | 360 | |
| tau_d | 1200 | |
| km_v_RuBisCO_c_CO2 | 0.014 | |
| km_v_RuBisCO_c_RUBP | 0.02 | |
| km_v_RuBisCO_c_O2 | 0.222 | |
| ki_v_RuBisCO_c_PGA | 2.52 | |
| ki_v_RuBisCO_c_NADP_st | 0.21 | |
| ki_v_RuBisCO_c_ADP_st | 0.2 | |
| ki_v_RuBisCO_c_Pi_st | 3.6 | |
| vmax_v_RuBisCO_c | 0.2 | |
| kcat_v_RuBisCO_c | 4.7 | |
| S_co_gas | 2200 | |
| vmax_v_PRKase | 1.17 | |
| keq_v_PRKase | 6846 | |
| km_v_PRKase_ATP_st | 0.625 | |
| ki_v_PRKase_ADP_st | 0.1 | |
| km_v_PRKase_RU5P | 0.034 | |
| ki_v_PRKase_PGA | 2 | |
| ki_v_PRKase_RUBP | 0.7 | |
| ki_v_PRKase_Pi_st | 4 | |
| vmax_v_pgareduction | 0.4 | |
| km_v_pgareduction_ATP_st | 0.3 | |
| km_v_pgareduction_PGA | 10 | |
| km_v_pgareduction_NADPH_st | 0.05 | |
| ki_v_pgareduction_ADP_st | 0.89 | |
| vmax_v_carbohydrate_synthesis | 0.2235 | |
| keq_v_carbohydrate_synthesis | 0.8 | |
| km_v_carbohydrate_synthesis_DHAP | 22 | |
| ki_v_carbohydrate_synthesis_ADP_st | 1 | |
| vmax_v_rpp | 0.0585 | |
| keq_v_rpp | 0.06 | |
| km_v_rpp_DHAP | 0.5 | |
| H | 0.00005012 | |
| vmax_v_co2_hydration | 200 | |
| keq_v_co2_hydration | 0.00056 | |
| km_v_co2_hydration_CO2 | 2.8 | |
| km_v_co2_hydration_HCO3 | 34 | |
| keq_v_FNR | 502 | |
| km_v_FNR_NADP_st | 0.0072 | |
| km_v_FNR_NADPH_st | 0.036 | |
| Kj_NADPH | 200 | |
| keq_v_ATPsynth | 5734 | |
| km_v_ATPsynth_ADP_st | 0.014 | |
| km_v_ATPsynth_Pi_st | 0.3 | |
| km_v_ATPsynth_ATP_st | 0.3 | |
| Kj_ATP | 200 | |
| gm | 0.5 | |
| Kh_co2 | 30303.0303030303 | |
| Kd | 150 | |
| Ki | 900 | |
| tau0 | -0.1 | |
| chi_beta | 0.5 | |
| phi | 0 | |
| pi_e | 1.2 | |
| Kh | 12 | |
| Ds | 10 | |
| gs0 | 0.01 | |
| NADP_tot | 0.5 |
| Symbol | ID | Equation |
|---|---|---|
| ADP_st | ||
| NADP_st | ||
| Pi_st | ||
| Et | ||
| km_v_RuBisCO_c_RUBP_extra | ||
| f_rubp | ||
| O2 | ||
| Ract_eq | ||
| I2_0 | ||
| I1_0 | ||
| chi | ||
| I1 | ||
| f_cyc | ||
| I2 | ||
| PhiPSII | ||
| J2 | ||
| J1 | ||
| f_pseudocyc | ||
| J_NADPH_steady | ||
| J_ATP_steady | ||
| gs_steady | ||
| A |
| Symbol | ID | Rate | Stoichiometry |
|---|---|---|---|
| Ract_rate | |||
| v_J_NADPH | |||
| v_J_ATP | |||
| v_gs | |||
| v_RuBisCO_c | |||
| rubisco_oxygenase | |||
| glycine_decarboxylase | |||
| v_PRKase | |||
| v_pgareduction | |||
| v_carbohydrate_synthesis | |||
| v_rpp | |||
| v_co2_hydration | |||
| v_RLight | |||
| v_FNR | |||
| v_ATPsynth | |||
| CO2_dissolution | |||
| CO2_stomatal_diffusion |
This model was validated by reproducing the following figures of the original publication.