Diatom plastids: Secondary endocytobiosis, plastid genome and protein import

Plastids of diatoms and other chromophytic algae have four surrounding membranes. In contrast to plastids of green algae, higher plants and red algae chromophytic cells are thought to have evolved by secondary endocytobiosis, i.e. by uptake of a eukaryotic photosynthetic organism by a eukaryotic host cell. This review gives a brief summary of the current views about the origin of diatom plastids and discusses possible mechanisms the cells might employ to transport nucleus‐encoded plastid proteins into these organelles.