Plastid Evolution

The ancestors of modern cyanobacteria invented O 2 -generating photosynthesis some 3.6 billion years ago. The conversion of water and CO 2 into energy-rich sugars and O 2 slowly transformed the planet, eventually creating the biosphere as we know it today. Eukaryotes didn't invent photosynthesis; they co-opted it from prokaryotes by engulfing and stably integrating a photoautotrophic prokaryote in a process known as primary endosymbiosis. After approximately a billion of years of coevolution, the eukaryotic host and its endosymbiont have achieved an extraordinary level of integration and have spawned a bewildering array of primary producers that now underpin life on land and in the water. No partnership has…