Rubisco substitutions predicted to enhance crop performance through carbon uptake modelling

Improving the performance of the CO2-fixing enzyme Rubisco is among the targets for increasing crop yields. Here, Earth system model (ESM) representations of canopy C-3 and C-4 photosynthesis were combined with species-specific Rubisco parameters to quantify the consequences of bioengineering foreign Rubiscos into C-3 and C-4 crops under field conditions. The 'two big leaf' (sunlit/shaded) model for canopy photosynthesis was used together with species-specific Rubisco kinetic parameters including maximum rate (K-cat), Michaelis-Menten constant for CO2 at ambient atmospheric O-2 (K-c(21%O2)), specificity for CO2 to O-2 (S-c/o), and associated heat activation (H-a) values. Canopy-scale consequences of replacing native Rubiscos in wheat, maize, and sugar beet with foreign enzymes from 27 species were modelled using data from Ameriflux and Fluxnet databases. Variation among the included Rubisco kinetics differentially affected modelled carbon uptake rates, and Rubiscos from several species of C-4 grasses showed the greatest potential of >50% carbon uptake improvement in wheat, and >25% improvement in sugar beet and maize. This study also reaffirms the need for data on fully characterized Rubiscos from more species, and for better parameterization of 'V-cmax' and temperature response of 'J(max)' in ESMs.

Automated summary

This study explores the potential of improving crop yields by introducing foreign Rubiscos, with Rubiscos from certain C-4 grasses showing significant carbon uptake improvement in wheat, sugar beet, and maize. The results highlight the importance of further research on Rubiscos from a wider range of species and better parameterization in Earth system models.