Partial characterization of the mitochondrial-dna of zea mays: ribosomal-rna, transfer-rna and rearrangements in cms strains
Bloomington, Ind., Indiana Univ., Diss., 1983
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| Sprache: | eng |
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Tag hinzufügen | Zusammenfassung: | Bloomington, Ind., Indiana Univ., Diss., 1983 Restriction digested maize mitochondrial DNA was utilized in cloning and hybridization experiments to localize the ribosomal and transfer RNA genes to specific segments of the genome. Cloned fragments were also employed in studies designed to characterize variations among mitochondrial genomes found in strains of maize exhibiting the cytoplasmically inherited 'male fertile' and 'male sterile' traits. We have mapped the genes for the ribosomal RNA molecules of maize mtDNA on a 32.2kb segment. The two genes occur as single copies and are separated from each other by a distance of about 15kb. An additional locus of hybridization to the 18S rRNA has also been identified and may represent chloroplast 16S ribosomal RNA sequence which is incorporated into the mitochondrial genome. Transfer RNA molecules have also been localized to specific restriction fragments of mtDNA. The exact number of genes cannot be estimated at present since some clustering occurs on specific restriction fragments. One mitochondrial tRNA gene, that of tRNA('His) has been sequenced and shown to be identical with maize chloroplast tRNA('His). We have also begun a preliminary characterization of the mtDNA present in strains of maize which carry the trait for Cytoplasmic Male Sterility (CMS). In these plants, mtDNA exhibits distinct organizational variation from normal male fertile strains. Our findings indicate that the rearrangement of sequence characteristic of CMS strains does not affect the 32kb segment on which the ribosomal genes reside nor any of the restriction fragments that carry tRNA gene sequences, with the exception of one additional site of tRNA homology in 'C' type CMS strains. Furthermore, a detailed analysis of the rearrangements found in several 'fertile' and 'CMS' type restriction fragments ties a large number of the observable variations between male sterile and male fertile mtDNA's to a single location in the genome. These results suggest that the rearranged sequences are representative of a more limited region of the DNA than had previously been assumed. |
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| Beschreibung: | 156 S. |