Minisymposium 20: Organelle Development
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M2001: Influence of mitochondrial genome stability on plant development
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Presenter: |
Mackenzie, Sally A Contact Presenter |
Authors | Shedge, Vikas (A) Arrieta-Montiel, Maria (A) Mohammed, Saleem (A) Sandhu, Ajay P (A) Christensen, Alan C (B) Mackenzie, Sally A (A) (B) | | Affiliations: |
(A): Plant Science Initiative, University of Nebraska, Lincoln, NE 68588
(B): School of Biological Sciences, University of Nebraska, Lincoln, NE 68588
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| Web Site: | http://psiweb.unl.edu/mackenzie | |
Plant mitochondrial genomes are recombinationally active to an unusually high degree in relation to their animal counterparts. The nature and adaptive value of this recombination activity is not clear, however there appear to be two functions served by this activity. High frequency homologous recombination appears to be involved in subdividing the genome to a multipartite organization. Lower frequency illegitimate recombination has been linked to the occurence of mitochondrial chimeric mutations that cause cytoplasmic male sterility, with obvious adaptive reproductive advantage in natural populations. We have investigated the nuclear regulation of illegitimate recombination in plant mitochondria using mutational analysis with initial emphasis on two nuclear loci: Msh1 and RecA3. Both appear to play distinct roles in suppressing ectopic recombination, although they can regulate recombination at related sites. Disruption of both Msh1 and RecA3 has a striking influence on plant growth, demonstrating the importance of mitochondrial genome stability to plant cell functions. Double mutants are dramatically reduced in growth rate (mitotic index), with marked changes in nuclear gene expression patterns as they relate to cell cycle control, redox regulation and mitochondrial biogenesis. Whereas the plant kingdom has capitalized on illegitimate recombination activity to implement gynodioecy as a reproductive strategy, clearly the multigenic regulation of nonhomologous recombination in mitochondria is crucial to growth.
