Optimizing plant photosynthetic productivity in current and projected climates will contribute to increased biomass production and crop yields, and to ensure food security. The regulation of the CO2-fixing enzyme, Rubisco, is not directed towards optimal photosynthesis and biomass production in crops systems. Results with model plant species provide evidence that manipulating Rubisco regulation to take full advantage of increases in light intensity has the potential to increase biomass production. This project will exploit differences in the properties of the enzyme that activates Rubisco in response to light, Rubisco activase, to increase CO2 assimilation in wheat. The goals of the project are: 1. To improve the light response of Rubisco activation and photosynthetic CO2 assimilation in wheat and 2. To understand the existing variation in the properties of different Rubisco activase isoforms and characterise the functional significance of this variation. The expected outcome is the generation of wheat germplasm with improved photosynthesis and biomass production under environments with variable light levels. This research is funded by a Rothamsted Research Career Fellowship and constitutes an important addition to achieve the goal of the 20:20 Wheat® ISP to increase wheat yield potential.