Unlocking grass leaf development: foundations for tunable cereal design

The grass leaf plays a critical role in global food security, generating the carbon stores in cereal grains, which provide > 50% of global calories. As the global population grows, there is an urgent need to increase food production using fewer resources and to develop more resilient agricultural systems to withstand variable climate conditions and rising socio-economic and environmental costs. Precision engineering of cereal crops, tailored to diverse environmental conditions and agronomic practices, is a vital strategy for achieving food security. Given the fundamental importance of the leaf in driving cereal productivity, it is an ideal engineering target. Leaf development occurs over large temporal and spatial scales and is environmentally regulated, posing significant challenges for predictive engineering approaches and limiting the feasibility of a one-size-fits-all approach. In this review, we synthesise current understanding of cereal leaf development and identify critical developmental biology questions that must be resolved to facilitate the truly programmable plants of the future.