title: Nucleotide substitution analyses of the glaucophyte Cyanophora suggest an ancestrally lower mutation rate in plastid vs mitochondrial DNA for the Archaeplastida.
abstract: A lot is known about the evolution and architecture of plastid, mitochondrial, and nuclear genomes, but surprisingly little is known about their relative rates of mutation. Most available relative-rate data come from seed plants, which, with few exceptions, have a mitochondrial mutation rate that is lower than those of the plastid and nucleus. But new findings from diverse plastid-bearing lineages have shown that for some eukaryotes the mitochondrial mutation rate is an order of magnitude greater than those of the plastid and nucleus. Here, we explore for the first time relative rates of mutation within the Glaucophyta-one of three main lineages that make up the Archaeplastida (or Plantae sensu lato). Nucleotide substitution analyses from distinct isolates of the unicellular glaucophyte Cyanophora paradoxa reveal 4-5-fold lower rates of mutation in the plastid and nucleus than the mitochondrion, which is similar to the mutational pattern observed in red algae and haptophytes, but opposite to that of seed plants. These data, together with data from previous reports, suggest that for much of the known photosynthetic eukaryotic diversity, plastid DNA mutations occur less frequently than those in mitochondrial DNA.
authors.affiliation: Department of Biology, University of Western Ontario, London, ON N6A 5B7, Canada. Electronic address: dsmit242@uwo.ca.
authors.forename: David Roy
authors.initials: DR
authors.lastname: Smith
authors.affiliation: Department of Biology, University of New Brunswick, Fredericton, NB E3B 5A3, Canada; Integrated Microbiology Program, Canadian Institute for Advanced Research, Canada.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Jackson
authors.affiliation: Department of Biology, University of New Brunswick, Fredericton, NB E3B 5A3, Canada; Integrated Microbiology Program, Canadian Institute for Advanced Research, Canada.
authors.forename: Adrian
authors.initials: A
authors.lastname: Reyes-Prieto
mesh_terms: D005075:Biological Evolution; D002467:Cell Nucleus / Q000235:genetics; D044424:Cyanophora / Q000145:classification* / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics*; D018744:DNA, Plant / Q000235:genetics; D016013:Likelihood Functions; D059645:Mutation Rate; D010802:Phylogeny; D018087:Plastids / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: D004272:DNA, Mitochondrial; D018744:DNA, Plant
keywords: Cyanelle; Genetic diversity; Nucleotide substitution; Organelle genome; Plastid genome