Plant Mitochondrial Recombination Surveillance Requires Unusual RecA and MutS Homologs

Authors

Vikas Shedge, University of Nebraska - LincolnFollow
Maria P. Arrieta-Montiel, University of Nebraska - Lincoln
Alan C. Christensen, University of Nebraska-LincolnFollow
Sally Ann MacKenzie, University of Nebraska-LincolnFollow

Date of this Version

2007

Citation

The Plant Cell, Vol. 19: 1251–1264, April 2007

Comments

Copyright 2007 American Society of Plant Biologists

Abstract

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.