| Summary: | <p>Abstract</p> <p>The mitochondrial genome of plants is-in every respect and for yet unclear reasons-very different from the well-studied one of animals. Thanks to next-generation sequencing technologies, Davila <it>et al</it>. precisely characterized the role played by recombination and DNA repair in controlling mitochondrial variations in <it>Arabidopsis thaliana</it>, thus opening new perspectives on the long-term evolution of this intriguing genome.</p> <p>See research article: <url>http://www.biomedcentral.com/1741-7007/9/64</url></p> <p>The mitochondrial genome of plants is a challenge to molecular evolutionary biologists. Its content is highly dynamic: plant mitochondrial DNA (mtDNA) is large and variable in size (200 to 2,500 kb), contains many introns and repeated elements (typically 90% of the total sequence), and experiences frequent gene gain/loss/transfer/duplication, and genome rearrangements <abbrgrp><abbr bid="B1">1</abbr></abbrgrp>. Its nucleotide substitution rate, paradoxically, is remarkably low-even lower than for nuclear DNA. These features are in sharp contrast with the highly studied mtDNA of animals, which is small-sized, structurally conserved, devoid of selfish elements, and has a very fast nucleotide substitution rate <abbrgrp><abbr bid="B2">2</abbr></abbrgrp>. Why these two genomes behave so differently is one of the most head-scratching questions of current comparative genomics. The study by Davila <it>et al</it>. <abbrgrp><abbr bid="B3">3</abbr></abbrgrp> contributes a potentially decisive argument by connecting the plant mtDNA mutation rate to yet another intriguing feature of this organellar genome-recombination.</p>
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