Enhancing crop yields through improvements in the efficiency of photosynthesis and respiration

The rate with which crop yields per hectare increase each year is plateauing at the same time that human population growth and other factors increase food demand. Increasing yield potential (Yp$$ {Y}_{\mathrm{p}} $$) of crops is vital to address these challenges. In this review, we explore a component of Yp$$ {Y}_{\mathrm{p}} $$ that has yet to be optimised - that being improvements in the efficiency with which light energy is converted into biomass (epsilon c$$ {\varepsilon}_{\mathrm{c}} $$) via modifications to CO2 fixed per unit quantum of light (alpha), efficiency of respiratory ATP production (epsilon prod$$ {\varepsilon}_{\mathrm{prod}} $$) and efficiency of ATP use (epsilon use$$ {\varepsilon}_{\mathrm{use}} $$). For alpha, targets include changes in photoprotective machinery, ribulose bisphosphate carboxylase/oxygenase kinetics and photorespiratory pathways. There is also potential for epsilon prod$$ {\varepsilon}_{\mathrm{prod}} $$ to be increased via targeted changes to the expression of the alternative oxidase and mitochondrial uncoupling pathways. Similarly, there are possibilities to improve epsilon use$$ {\varepsilon}_{\mathrm{use}} $$ via changes to the ATP costs of phloem loading, nutrient uptake, futile cycles and/or protein/membrane turnover. Recently developed high-throughput measurements of respiration can serve as a proxy for the cumulative energy cost of these processes. There are thus exciting opportunities to use our growing knowledge of factors influencing the efficiency of photosynthesis and respiration to create a step-change in yield potential of globally important crops.

Automated summary

This review explores the potential to increase crop yield potential by optimizing the efficiency of converting light energy into biomass, respiratory ATP production, and ATP use. By targeting factors such as photoprotective machinery, enzymatic kinetics, and metabolic pathways, it is possible to significantly enhance the yield potential of globally important crops.