Plant organelle division orchestrated by the mosaic machinery of endosymbiotic relics and eukaryotic host factors.

Plastids retain the imprint of their cyanobacterial ancestry by dividing primarily through binary fission. This process is executed by elaborate division machinery that has continued to evolve since endosymbiosis. Early identification and characterization of the Arabidopsis accumulation and replication of chloroplasts (arc) mutants paved the way for the molecular dissection of the plastid division apparatus, whose components have both the prokaryotic ancestral and eukaryotic host origins. Molecular and cell biological studies revealed that plastid division operates through interdependent interactions among the Min-system positioning factors, the stromal FtsZ ring, envelope-associated ARC6, PARC6, and PDV proteins, and cytosolic ARC5/DRP5B proteins, which act in concert to position the division site and drive plastid separation under developmental and environmental regulation. Comparisons with mitochondrial and peroxisomal proliferation unveil shared division factors among these metabolically connected organelles. Insights into plant organelle division may inform strategies for the manipulation of organelle abundance to improve crop quality and resilience.