Pyrenoid Structure, Function, Evolution, and Characterization Across Diverse Lineages

Pyrenoids are eukaryotic CO₂-fixing organelles that are evolutionarily diverse, globally abundant, and critical to global carbon cycling. Despite being described over 200 years ago, the vast majority of our molecular understanding of pyrenoids has emerged only in the past decade. Here, we review the recent advances in characterizing pyrenoid structure, function, and evolutionary variation across lineages containing primary, secondary, and tertiary plastids of both red and green origins. We outline experimental frameworks that can be used to answer key questions about these enigmatic organelles. We discuss the utility of pyrenoids as model biomolecular condensates for investigating fundamental properties of liquid-liquid phase separation. Finally, we summarize how understanding convergently evolved pyrenoids across diverse lineages may be used to advance efforts to engineer functional pyrenoids into crop plants to enhance CO₂ fixation for yield improvements and carbon dioxide removal.