Primary producers during the early Earth

Primary producers convert light energy from the sun into chemical energy in the form of sugars, a fundamental process that has enabled life on Earth. Once ancestral cyanobacteria evolved, they played a crucial role in Earth's history by facilitating the rise of atmospheric oxygen, paving the way for the development of complex life forms. Despite its significance, the origins of photosynthesis are still not fully understood. During the talk, I will highlight key evolutionary events in the history of Cyanobacteria: 1) the Archean origin of PSII,  photochemical reaction centre that catalyses the light-driven oxidation of water to molecular oxygen; 2) the emergence of the crown group of Cyanobacteria; 3) the appearance of filamentous forms around the Great Oxidation Event at 2.32 Ga; and 4) the late emergence of marine planktonic groups between 800-600 Mya. Molecular evolution analyses reveal a significant time gap between the Archean origin of oxygenic photosynthesis and the appearance of planktonic forms at the end of the Precambrian era. By studying the 'genomic record,' we can now unravel how oxygenic phototrophs co-evolved with the Earth's biosphere, contributing to the habitability of our planet.