Columbia, Missouri
University of Missouri
St. Louis, Missouri
Washington University
Salt Lake City, Utah
University of Utah
Sequence, expression and evolution of mitochondrial genomes in the genus Zea --Newton, K, Clifton, SW, Fauron, C Plant mitochondrial genomes are unusual in their diversity of structure and rapidity of change. Although most of the known coding regions are very conserved, large intergenic regions show no sequence similarities. These "non-coding" regions have important roles in the rapid structural evolution seen for plant mitochondrial genomes, and they can become functional as components of chimeric genes that have been described as being responsible for several cases of cytoplasmic male sterility (CMS). In order to understand how non-coding regions of mitochondrial genomes contribute to their structural and functional diversity, it is necessary to examine closely related species. To address these issues, five mitochondrial genomes within the genus Zea, including fertile and CMS mtDNAs of maize, Zea parviglumis (the probable progenitor of maize), Zea perennis (from the most distant section of the teosintes), will be sequenced and compared to the mtDNA sequences of a related grass, Tripsacumdactyloides and a more distantly related plant, Sorghum bicolor. A direct sequencing approach will be complemented with the efficient mapping of several Zea mitochondrial genotypes. The regions of a fertile maize mitochondrial genome that are functional will be determined by expression analyses using mitochondrial RNAs from different tissues and stages of development. Previous data indicated that some mitochondrial genes are expressed preferentially during specific stages of development. The extent of this diversity of expression will be examined. This NSF-funded genomeproject willcontribute to an understanding of the content, organization and expression of grass mitochondrial genomes.
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