Screens into the natural catalytic diversity of the photosynthetic CO2-fixing enzyme Rubisco over the last decade have revealed significant plasticity in carboxylation potential that challenge the antiquated views of kinetic trade-offs in speed and CO2-selectivitiy that underpin scepticism the inherent potential for improving Rubisco performance is constrained. In this talk I will discuss the use of directed evolution using E. coli as a feasible pathway for generating ‘better-than-nature’ step changes in Rubisco performance that are needed to visibly improve plant growth.