Rubisco substitutions predicted to enhance crop performance through carbon uptake modelling

Abstract

Improving the performance of the CO2-fixing enzyme Rubisco is among targets for increasing crop yields. Here, Earth system model (ESM) representations of canopy C3 and C4 photosynthesis were combined with species-specific Rubisco parameters to quantify the consequences of bioengineering foreign Rubiscos into C3 and C4 crops under field conditions. The “two big leaf” (sunlit/shaded) model for canopy photosynthesis was used together with species-specific Rubisco kinetics parameters including maximum rate (Kcat), Michaelis-Menten constant for CO2 at ambient atmospheric O2 (Kc 21%O2), specificity for CO2 to O2 (Sc/o), and associated heat activation (Ha) 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 C4 grasses showed the greatest potential of over 50% carbon uptake improvement in wheat, and over 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 parameterisation of ‘Vcmax’ and temperature response of ‘Jmax’ in ESMs.

The small subunit of Rubisco and its potential as an engineering target

“…Furthermore, any increases in Rubisco CO 2 assimilation may benefit from additional modifications in downstream fluxes, for example the transport of carbohydrates to sink tissues ( Wang et al , 2020 ). Modified canopy-scale models that account for Rubisco parameters may help further to predict the physiological consequences of replacing native Rubiscos with heterologous enzymes in plants ( Iqbal et al , 2021 ).…”

Improving the efficiency of Rubisco by resurrecting its ancestors in the family Solanaceae

“…Biochemical models predicted that installing selected C 4 Rubiscos in C 3 plants could improve photosynthesis by more than 25% ( 9 , 35 ). Previous attempts to capture kinetic signatures of C 4 Rubiscos were mostly performed through evolutionary analyses of the L subunits, with limited success ( 6 – 8 , 10 , 36 , 37 ). Despite multiple lines of evidence showing the influence of both subunits on catalysis ( 16 , 19 , 38 – 41 ), it is still challenging to carry out large-scale phylogenetic analyses of the S subunits in plants due to the lack of available sequences except in a relatively small number of model species.…”

Dissecting Succulence: Crassulacean Acid Metabolism and Hydraulic Capacitance are Independent Adaptations in Clusia Leaves

“…In addition to comparing the contributions of different adaptations during drought, modelling can provide valuable insights into the ways in which physiological traits interact with different forms of photosynthesis (Iqbal et al , 2021). Our model found that C FT had a substantially smaller effect on gas exchange rates and diel Ψ L in the CAM background, in comparison to the C 3 simulations ( Fig.…”