In recent years crop yields have reached a plateau per hectare of land and are projected to not meet the demands of the growing global population1. Additionally, there is an increasing demand for sustainable fuels derived from crop biomass requiring more land use2. Increasing CO2 assimilation by improving photosynthesis could be the next green revolution, allowing for increased crop yields for food and fuel3. C4 crops represent major food crops and biomass sources for biofuel. C4 plants achieve this due to the carbon concentrating mechanism (CCM) of C4 photosynthesis allowing higher CO2 assimilation compared to C3 plants4. The C4 CCM obtains additional ATP production by Cyclic Electron Flow (CEF) wherein electrons are diverted away from NADPH production and back towards ATP production5. One of these genes involved in CEF, the PGR5-Like Photosynthetic Phenotype 1 (PGRL1), duplicated early in the grass family (Poaceae) and shows cell-differential regulation in NADP-ME subtype C4 grasses. My project aims to elucidate the cell-specific and -differential expression of proteins involved in CEF. I also aim to increase CEF in C4 grasses to further improve ATP synthesis and CO2 assimilation.