Abstract
Chloroplasts originated more than 1 billion years ago when a cyanobacterial cell became an endosymbiont in a eukaryotic cell. Reminiscent of their free-living ancestors, chloroplasts replicate by binary fission, but the division is controlled by the eukaryotic host cell. Recent studies have shown that chloroplast division is performed by a macromolecular protein complex at the division site, encompassing both the inside and the outside of the two envelope membranes. The division complex has retained certain components of the cyanobacterial division complex and several other components that have been developed by the host cell. On the basis of the information about the division complex, we are beginning to understand how the division complex evolved, and how eukaryotic host cells regulate chloroplast division during proliferation and differentiation. In this review, we summarize the recent rapid progress in our understanding of the chloroplast division machinery and its regulation.
