Bibliography: leaves 84-94 / vii, 94, [39] leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, 1987

Thesis (M.S.)--Northern Michigan University, 2007. / Bibliography: leaves 44-48.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 86-93). Also available on the World Wide Web.

Graduation date: 1997

Graduation date: 1997

Frequent rearrangements, typically through homologous recombination in plant mitochondrial genomes often result in different upstream and downstream sequences for the same gene among a number of species. Transcription and RNA processing signals are therefore different, even among closely related plants. To evaluate the impact of DNA rearrangements on gene expression I conducted a comparative analysis of the S7 ribosomal protein gene (rps7) among a number of grasses: wheat, rice, maize, barley, rye, brome, Lolium and oats (grasses whose evolutionary divergence times range from about 5 to 60 Mya). Using circularized-RT-PCR to simultaneously map rps7 transcript termini I found that 3’ends for various RNA species are homogeneous, mapping to conserved sequences among plants. 5’ termini are more complex and can be both discrete and heterogeneous for different transcripts, both within and among plants. Genome rearrangements upstream of the rps7 start codon for some but not all species has led to plant-specific signals for both rps7 transcription and RNA processing. Termini for rps7 precursor species in wheat and Lolium are very discrete and likely use different upstream tRNAs as processing signals for end-cleavage. A number of potential stem-loop structures have also been identified at or near 5’ and 3’ termini which may function in maturation of transcript ends or provide transcript stability and protection from degradation by ribonucleases. C-to-U RNA editing of non-coding sequences, a rare event, was observed at multiple sites within the 5’ and 3’UTRs among plants. Some sites may even be developmentally regulated as CR-RT-PCR experiments were conducted using mitochondrial RNA isolated from seedlings and germinating embryos. Taken together, my observations demonstrate the frequency of upstream DNA rearrangements and the variety of signals used for expression of rps7 among grasses, providing new insights into the complexities of mRNA production in plant mitochondria.

In this study I assessed the potentials of selected, established perennial grasses to maintain site occupancy in the foothills ecosystem of the Rogue River Valley of southwest Oregon which is currently dominated by a variety of annual plants. The first evaluation compared growth curves of the perennial grasses and contrasted them to growth patterns of residual annual plants. Periods of growth varied among the perennial grasses studied. Of the perennial grasses, Idaho fescue (Festuca idahoensis), a native, and Berber orchardgrass (Dactylis glomerata var. 'Berber'), introduced, most closely emulated the growth patterns of the majority of the annual plants. Relative to the other perenial grasses tested, they initiated growth earlier, continued some growth through the winter and matured earlier. Once established, they should be able to effectively compete with the resident annuals for resources and maintain their populatiOhs. To assess the potential for competition for available moisture, the second evaluation considered timing and extent of soil moisture extraction by the perennial grasses and the resident annual community through the periods of active growth. This verified growth analysis results. Idaho fescue and Berber orchardgrass extracted moisture earlier than the other perennial grasses. Perennial grass plots and plots dominated by yellow starthistle (Centaurea solstitialis) end of season residual soil moisture levels were similar. Resident annual grasses left considerably more soil moisture. In years with an early summer drought, the earlier growing perennial grasses should be able to satisfy growth requirements and persist. An assessment was also made of the abilities of several selected established perennial grasses to resist reinvasion by resident annual plants. Earlier growing perennial grasses such as Berber orchardgrass and Idaho fescue suppressed the annuals more effectively than the later growing perennial grasses. Of the perennial grasses studied, those emulating the growth patterns of the annuals have been the Most competitive and have maintained the most vigorous stands. / Graduation date: 1990

Frequent rearrangements, typically through homologous recombination in plant mitochondrial genomes often result in different upstream and downstream sequences for the same gene among a number of species. Transcription and RNA processing signals are therefore different, even among closely related plants. To evaluate the impact of DNA rearrangements on gene expression I conducted a comparative analysis of the S7 ribosomal protein gene (rps7) among a number of grasses: wheat, rice, maize, barley, rye, brome, Lolium and oats (grasses whose evolutionary divergence times range from about 5 to 60 Mya). Using circularized-RT-PCR to simultaneously map rps7 transcript termini I found that 3’ends for various RNA species are homogeneous, mapping to conserved sequences among plants. 5’ termini are more complex and can be both discrete and heterogeneous for different transcripts, both within and among plants. Genome rearrangements upstream of the rps7 start codon for some but not all species has led to plant-specific signals for both rps7 transcription and RNA processing. Termini for rps7 precursor species in wheat and Lolium are very discrete and likely use different upstream tRNAs as processing signals for end-cleavage. A number of potential stem-loop structures have also been identified at or near 5’ and 3’ termini which may function in maturation of transcript ends or provide transcript stability and protection from degradation by ribonucleases. C-to-U RNA editing of non-coding sequences, a rare event, was observed at multiple sites within the 5’ and 3’UTRs among plants. Some sites may even be developmentally regulated as CR-RT-PCR experiments were conducted using mitochondrial RNA isolated from seedlings and germinating embryos. Taken together, my observations demonstrate the frequency of upstream DNA rearrangements and the variety of signals used for expression of rps7 among grasses, providing new insights into the complexities of mRNA production in plant mitochondria.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb. 12, 2010 ). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dr. Robert L. Kallenbach, Thesis Supervisor. Includes bibliographical references.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.