One, two, three: nature's tool box for building plastids

Abstract

Plastids were acquired by different strategies. While in primary endosymbiosis a cyanobacterium was engulfed by a eukaryotic cell and reduced to a plastid, secondarily evolved plastids trace back to an enslaved red or green alga. Nature's recent playground in merging organisms together can be detected in dinoflagellates, which developed additional strategies to acquire their solar-powered factory. Some dinoflagellates possess secondary plastids, other species temporarily use "stolen plastids" of different origin. The highest degree of complexity is reached in dinoflagellates with chloroplasts originating from the uptake of a photosynthetic symbiont with secondary plastids, a process termed tertiary endosymbiosis.