Organelle heredity

Chloroplasts and mitochondria derive from free-living bacteria and possess their own genomes. Organellar genomes retain many of the essential genes for photosynthesis/respiration and organelle biogenesis. However, their replication, repair, and inheritance depend largely on nuclear gene products. Extant chloroplasts and mitochondria generally possess multicopy genomes localized within nucleoids, whose organization and regulation will provide critical information to elucidate how free-living bacteria evolved into eukaryotic organelles. This chapter reviews work on this subject in Chlamydomonas, including historical milestones and recent progress. Research highlights emphasize two topics: the dynamic regulation of chloroplast nucleoids during mitosis, and the uniparental inheritance of chloroplast DNA, involving selective degradation, during sexual reproduction.