title: Mitochondrial and plastid genome architecture: Reoccurring themes, but significant differences at the extremes.
abstract: Mitochondrial and plastid genomes show a wide array of architectures, varying immensely in size, structure, and content. Some organelle DNAs have even developed elaborate eccentricities, such as scrambled coding regions, nonstandard genetic codes, and convoluted modes of posttranscriptional modification and editing. Here, we compare and contrast the breadth of genomic complexity between mitochondrial and plastid chromosomes. Both organelle genomes have independently evolved many of the same features and taken on similar genomic embellishments, often within the same species or lineage. This trend is most likely because the nuclear-encoded proteins mediating these processes eventually leak from one organelle into the other, leading to a high likelihood of processes appearing in both compartments in parallel. However, the complexity and intensity of genomic embellishments are consistently more pronounced for mitochondria than for plastids, even when they are found in both compartments. We explore the evolutionary forces responsible for these patterns and argue that organelle DNA repair processes, mutation rates, and population genetic landscapes are all important factors leading to the observed convergence and divergence in organelle genome architecture.
authors: Department of Biology, University of Western Ontario, London, ON, Canada N6A 5B7; and dsmit242@uwo.ca.
authors: David Roy
authors: http://orcid.org/0000-0001-9560-5210
authors: DR
authors: Smith
authors: Canadian Institute for Advanced Research, Department of Botany, University of British Columbia, Vancouver, BC, Canada V6T 1Z4.
authors: Patrick J
authors: PJ
authors: Keeling
mesh_terms: D000818:Animals; D005075:Biological Evolution; D019070:Cell Lineage; D002467:Cell Nucleus / Q000235:genetics; D002875:Chromosomes / Q000648:ultrastructure; D004260:DNA Repair; D004272:DNA, Mitochondrial / Q000235:genetics; D005828:Genetics, Population; D016678:Genome; D054629:Genome, Mitochondrial; D023281:Genomics; D006801:Humans; D009154:Mutation; D009711:Nucleotides / Q000235:genetics; D010944:Plants; D018087:Plastids / Q000235:genetics*; D012323:RNA Processing, Post-Transcriptional; D017422:Sequence Analysis, DNA; D013559:Symbiosis / Q000235:genetics
chemical_list: D004272:DNA, Mitochondrial; D009711:Nucleotides
keywords: chloroplast; endosymbiosis; mitochondrial genome; mitochondrion; plastid genome