MitochondrialDNARepair and Genome Evolution

Abstract In plants, replicating the mitochondrial genome is probably a very minor expenditure of energy compared to the other costly activities of the cell, including replicating the much larger nuclear genome, transcription, protein synthesis and active transport. This chapter discusses the angiosperm mitochondrial genomes. The mutational burden hypothesis (MBH) explains an inverse correlation between mutation rate and genome size. The types of DNA damage that occur in mitochondria, the available mechanisms of repair, and selection on the repaired DNA products is taken into account in understanding the patterns of plant mitochondrial genome evolution. Analysis of the evolutionary patterns seen in plant mitochondrial genomes led to hypotheses of what mechanisms of DNA repair are available in plant mitochondria. The mechanism of repair ensures accurate inheritance of genes and has the side‐effect of allowing duplications, rearrangements and the accumulation of junk DNA.