biostudies-literatureSuzuki SNatural Environment Research Councilmsac001https://www.ebi.ac.uk/biostudies/studies/S-EPMC8829904biostudies-literatureUnknown39(2)In many lineages of algae and land plants, photosynthesis was lost multiple times independently. Comparative analyses of photosynthetic and secondary nonphotosynthetic relatives have revealed the essential functions of plastids, beyond photosynthesis. However, evolutionary triggers and processes that drive the loss of photosynthesis remain unknown. Cryptophytes are microalgae with complex plastids derived from a red alga. They include several secondary nonphotosynthetic species with closely related photosynthetic taxa. In this study, we found that a cryptophyte, Cryptomonas borealis, is in a stage just prior to the loss of photosynthesis. Cryptomonas borealis was mixotrophic, possessed photosynthetic activity, and grew independent of light. The plastid genome of C. borealis had distinct feMolecular biology and evolutionWhat Happened before Losses of Photosynthesis in Cryptophyte Algae?PMC8829904NE/R017050/1Matsuzaki RSuzuki SYamaguchi HKawachi MfalseWhat Happened before Losses of Photosynthesis in Cryptophyte Algae?In many lineages of algae and land plants, photosynthesis was lost multiple times independently. Comparative analyses of photosynthetic and secondary nonphotosynthetic relatives have revealed the essential functions of plastids, beyond photosynthesis. However, evolutionary triggers and processes that drive the loss of photosynthesis remain unknown. Cryptophytes are microalgae with complex plastids derived from a red alga. They include several secondary nonphotosynthetic species with closely related photosynthetic taxa. In this study, we found that a cryptophyte, Cryptomonas borealis, is in a stage just prior to the loss of photosynthesis. Cryptomonas borealis was mixotrophic, possessed photosynthetic activity, and grew independent of light. The plastid genome of C. borealis had distinct fe2022-01-01T00:00:00Z2022 Feb2026-04-08T17:45:05.621Z2025-04-06T12:08:25.393ZS-EPMC88299043507979710.1093/molbev/msac001