Bellasio 2019, Photosynth. Res.

edit Edit

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.

Scheme

Bellasio 2019 scheme

Analysis

Model definition

Variables
SymbolIDInitial value
CO2
HCO30.1327
RUBP2
PGA4
DHAP4
ATP_st0.68
NADPH_st0.21
RU5P0.34
Ract1
J_NADPH0.1
J_ATP0.16
Ci
gs0.334934046786077
Parameters
SymbolIDValue
AP_tot1.5
Pi_tot15
p_o2210000
Kh_o2833300
V_m0.03
PPFD1500
RLight0.001
s0.43
PhiPSII_LL0.72
PhiPSI_LL1
alpha_ppfd_PhiPSII0.00125
V0_ppfd_PhiPSII-0.8
theta_ppfd_PhiPSII0.7
f_pseudocycNR0.01
fq1
f_ndh0
h4
Ca350
alpha_ppfd_rub0.0018
V0_ppfd_rub0.16
theta_ppfd_rub0.95
alpha_co2400
V0_co2-0.2
theta_co20.98
tau_i360
tau_d1200
km_v_RuBisCO_c_CO20.014
km_v_RuBisCO_c_RUBP0.02
km_v_RuBisCO_c_O20.222
ki_v_RuBisCO_c_PGA2.52
ki_v_RuBisCO_c_NADP_st0.21
ki_v_RuBisCO_c_ADP_st0.2
ki_v_RuBisCO_c_Pi_st3.6
vmax_v_RuBisCO_c0.2
kcat_v_RuBisCO_c4.7
S_co_gas2200
vmax_v_PRKase1.17
keq_v_PRKase6846
km_v_PRKase_ATP_st0.625
ki_v_PRKase_ADP_st0.1
km_v_PRKase_RU5P0.034
ki_v_PRKase_PGA2
ki_v_PRKase_RUBP0.7
ki_v_PRKase_Pi_st4
vmax_v_pgareduction0.4
km_v_pgareduction_ATP_st0.3
km_v_pgareduction_PGA10
km_v_pgareduction_NADPH_st0.05
ki_v_pgareduction_ADP_st0.89
vmax_v_carbohydrate_synthesis0.2235
keq_v_carbohydrate_synthesis0.8
km_v_carbohydrate_synthesis_DHAP22
ki_v_carbohydrate_synthesis_ADP_st1
vmax_v_rpp0.0585
keq_v_rpp0.06
km_v_rpp_DHAP0.5
H0.00005012
vmax_v_co2_hydration200
keq_v_co2_hydration0.00056
km_v_co2_hydration_CO22.8
km_v_co2_hydration_HCO334
keq_v_FNR502
km_v_FNR_NADP_st0.0072
km_v_FNR_NADPH_st0.036
Kj_NADPH200
keq_v_ATPsynth5734
km_v_ATPsynth_ADP_st0.014
km_v_ATPsynth_Pi_st0.3
km_v_ATPsynth_ATP_st0.3
Kj_ATP200
gm0.5
Kh_co230303.0303030303
Kd150
Ki900
tau0-0.1
chi_beta0.5
phi0
pi_e1.2
Kh12
Ds10
gs00.01
NADP_tot0.5
Derived quantities
SymbolIDEquation
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
Reactions
SymbolIDRateStoichiometry
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

Curation

Curator's note

This model was validated by reproducing the following figures of the original publication.

Figures
Fig3
Page figure
Fig4
Page figure
Fig5
Page figure
Fig6
Page figure
Fig7
Page figure