Prospects for improving CO₂ fixation in C₃-crops through understanding C₄-Rubisco biogenesis and catalytic diversity

Abstract

By operating a CO₂ concentrating mechanism, C₄-photosynthesis offers highly successful solutions to remedy the inefficiency of the CO₂-fixing enzyme Rubisco. C₄-plant Rubisco has characteristically evolved faster carboxylation rates with low CO₂ affinity. Owing to high CO₂ concentrations in bundle sheath chloroplasts, faster Rubisco enhances resource use efficiency in C₄ plants by reducing the energy and carbon costs associated with photorespiration and lowering the nitrogen investment in Rubisco. Here, we show that C₄-Rubisco from some NADP-ME species, such as maize, are also of potential benefit to C₃-photosynthesis under current and future atmospheric CO₂ pressures. Realizing this bioengineering endeavour necessitates improved understanding of the biogenesis requirements and catalytic variability of C₄-Rubisco, as well as the development of transformation capabilities to engineer Rubisco in a wider variety of food and fibre crops.