title: Massive and widespread organelle genomic expansion in the green algal genus Dunaliella.
abstract: The mitochondrial genomes of chlamydomonadalean green algae are renowned for their highly reduced and conserved gene repertoires, which are almost fixed at 12 genes across the entire lineage. The sizes of these genomes, however, are much more variable, with some species having small, compact mitochondrial DNAs (mtDNAs) and others having expanded ones. Earlier work demonstrated that the halophilic genus Dunaliella contains extremely inflated organelle genomes, but to date the mtDNA of only one isolate has been explored. Here, by surveying mtDNA architecture across the Chlamydomonadales, we show that various Dunaliella species have undergone massive levels of mitochondrial genomic expansion, harboring the most inflated, intron-dense mtDNAs available from chlorophyte green algae. The same also appears to be true for their plastid genomes, which are potentially among the largest of all plastid-containing eukaryotes. Genetic divergence data are used to investigate the underlying causes of such extreme organelle genomic architectures, and ultimately reveal order-of-magnitude differences in mitochondrial versus plastid mutation rates within Dunaliella.
authors: Department of Biology, University of Western Ontario, London, Ontario, Canada.
authors: Michael
authors: M
authors: Del Vasto
authors: Department of Biology, Canadian Institute for Advanced Research, Integrated Microbial Biodiversity Program, University of New Brunswick, Fredericton, New Brunswick, Canada.
authors: Francisco
authors: F
authors: Figueroa-Martinez
authors: Department of Molecular Medicine and Sydney Brenner Institute for Molecular Biosciences, University of the Witwatersrand, Johannesburg, South Africa Agricultural Research Council, Biotechnology Platform, Pretoria, South Africa.
authors: Jonathan
authors: J
authors: Featherston
authors: Departamento de Botánica, Facultad de Ciencias Naturales y Oceanógraficas. Universidad de Concepción, Casilla, Concepción, Chile.
authors: Mariela A
authors: MA
authors: González
authors: Department of Biology, Canadian Institute for Advanced Research, Integrated Microbial Biodiversity Program, University of New Brunswick, Fredericton, New Brunswick, Canada.
authors: Adrian
authors: A
authors: Reyes-Prieto
authors: Department of Molecular Medicine and Sydney Brenner Institute for Molecular Biosciences, University of the Witwatersrand, Johannesburg, South Africa Department of Biodiversity and Conservation Biology, Faculty of Natural Sciences, University of the Western Cape, Belville, Cape Town, South Africa.
authors: Pierre M
authors: PM
authors: Durand
authors: Department of Biology, University of Western Ontario, London, Ontario, Canada dsmit242@uwo.ca.
authors: David Roy
authors: DR
authors: Smith
mesh_terms: D000460:Chlorophyta / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000737:chemistry; D019143:Evolution, Molecular; D059646:Genome Size; D054628:Genome, Chloroplast; D054629:Genome, Mitochondrial
chemical_list: D004272:DNA, Mitochondrial
keywords: Chlamydomonas; Polytoma; intron; mitochondrial DNA; plastid DNA