Towards engineering carboxysomes into C3 plants

Summary Photosynthesis in C3 plants is limited by features of the carbon‐fixing enzyme Rubisco, which exhibits a low turnover rate and can react with O 2 instead of CO 2 , leading to photorespiration. In cyanobacteria, bacterial microcompartments, known as carboxysomes, improve the efficiency of photosynthesis by concentrating CO 2 near the enzyme Rubisco. Cyanobacterial Rubisco enzymes are faster than those of C3 plants, though they have lower specificity toward CO 2 than the land plant enzyme. Replacement of land plant Rubisco by faster bacterial variants with lower CO 2 specificity will improve photosynthesis only if a microcompartment capable of concentrating CO 2 can also be installed into the chloroplast. We review current information about cyanobacterial microcompartments and carbon‐concentrating mechanisms, plant transformation strategies, replacement of Rubisco in a model C3 plant with cyanobacterial Rubisco and progress toward synthesizing a carboxysome in chloroplasts.