Plant mitochondrial recombination surveillance requires unusual RecA and MutS homologs.
For >20 years, the enigmatic behavior of plant mitochondrial genomes has been well described but not well understood. Chimeric genes appear, and occasionally are differentially replicated or expressed, with significant effects on plant phenotype, most notably on male fertility, yet the mechanisms of DNA replication, chimera formation, and recombination have remained elusive. Using mutations in two important genes of mitochondrial DNA metabolism, we have observed reproducible asymmetric recombination events occurring at specific locations in the mitochondrial genome. Based on these experiments and existing models of double-strand break repair, we propose a model for plant mitochondrial DNA replication, chimeric gene formation, and the illegitimate recombination events that lead to stoichiometric changes. We also address the physiological and developmental effects of aberrant events in mitochondrial genome maintenance, showing that mitochondrial genome rearrangements, when controlled, influence plant reproduction, but when uncontrolled, lead to aberrant growth phenotypes and dramatic reduction of the cell cycle.
Shedge
Vikas
V
Plant Science Initiative, University of Nebraska, Lincoln, Nebraska 68588-0660, USA.
Arrieta-Montiel
Maria
M
Christensen
Alan C
AC
Mackenzie
Sally A
SA
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018745:Genome, Plant; D008928:Mitochondria / Q000235:genetics*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D051719:MutS DNA Mismatch-Binding Protein / Q000235:genetics* / Q000378:metabolism; D010944:Plants / Q000235:genetics*; D011938:Rec A Recombinases / Q000235:genetics / Q000378:metabolism*; D011995:Recombination, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D024101:Mitochondrial Proteins; D011938:Rec A Recombinases; C523213:MSH1 protein, Arabidopsis; D051719:MutS DNA Mismatch-Binding Protein