Plant mitochondrial genome evolution can be explained by DNA repair mechanisms

Alan C. Christensen

Research output: Contribution to journalArticlepeer-review

126 Scopus citations


Plant mitochondrial genomes are notorious for their large and variable size, nonconserved open reading frames of unknown function, and high rates of rearrangement. Paradoxically, the mutation rates are very low. However, mutation rates can only be measured in sequences that can be aligned-a very small part of plant mitochondrial genomes. Comparison of the complete mitochondrial genome sequences of two ecotypes of Arabidopsis thaliana allows the alignment of noncoding as well as coding DNA and estimation of the mutation rates in both. A recent chimeric duplication is also analyzed. A hypothesis is proposed that the mechanisms of plant mitochondrial DNA repair account for these features and includes different mechanisms in transcribed and nontranscribed regions. Within genes, a bias toward gene conversion would keep measured mutation rates low, whereas in noncoding regions, break-induced replication (BIR) explains the expansion and rearrangements. Both processes are types of double-strand break repair, but enhanced second-strand capture in transcribed regions versus BIR in nontranscribed regions can explain the two seemingly contradictory features of plant mitochondrial genome evolution-the low mutation rates in genes and the striking expansions of noncoding sequences.

Original languageEnglish (US)
Pages (from-to)1079-1086
Number of pages8
JournalGenome Biology and Evolution
Issue number6
StatePublished - Jun 2013
Externally publishedYes


  • Arabidopsis
  • DNA repair
  • Mitochondrial genome
  • Mutation rate

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics


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