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Genome sizing and fire blight resistance screening in Cotoneaster

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dc.contributor.advisor Contreras, Ryan N.
dc.creator Rothleutner, Joseph J.
dc.date.accessioned 2012-07-26T17:42:29Z
dc.date.available 2012-07-26T17:42:29Z
dc.date.copyright 2012-06-15
dc.date.issued 2012-06-15
dc.identifier.uri http://hdl.handle.net/1957/31572
dc.description Graduation date: 2013 en_US
dc.description.abstract Cotoneaster is an ornamental shrub valued for showy flowers, berries and architecture as well as the ability tolerate adverse conditions under which other taxa fail. Cotoneaster is a highly diverse genus of over 400 species, of which few are available in the US nursery trade. Some species commercially available have been identified as potentially invasive in the state of Oregon and also are susceptible to the bacterial disease fire blight. Cotoneaster selections with reduced fertility and disease resistance would be desirable characteristics for low input landscape plants. A goal of my research was to characterize Cotoneaster spp. to provide information for the rationale planning and development of novel clones to meet these horticultural goals. In the first study, genome sizes were estimated using flow cytometery and ploidy levels were inferred using holoploid genome size. Observed differences in monoploid genome sizes translate to a difference in chromosome size. Differences in chromosome size may present a reproductive barrier when they are large. This may pose a challenge in wide crosses, but may be utilized to achieve sterility in the F1 interspecific hybrid population. Differences in genome size are not related to taxonomic ordering, so wide inter sectional and inter subgeneric crosses may be possible. In the second study, susceptibility of Cotoneaster to fire blight was measured on plants inoculated with Erwinia amylovora strain Ea153. In greenhouse assays conducted over two years, plants were inoculated by cutting leaves with scissors infested with the pathogen. Some species were 'highly susceptible' to fire blight where plants were killed to the ground, and others were rated 'highly resistant' and no lesions were observed. Seventeen accessions were rated as resistant to fire blight This research provides the first report of ploidy, genome sizes, and susceptibility of species of Cotoneaster to fire blight. Collectively this research provides a toolbox for a breeder to tackle the challenge of creating disease resistant cultivars with reduced fertility. en_US
dc.language.iso en_US en_US
dc.subject Maloideae en_US
dc.subject Flow cytometry en_US
dc.subject Cytology en_US
dc.subject Erwinia amylovora en_US
dc.subject Breeding en_US
dc.subject Ploidy en_US
dc.subject base pair composition en_US
dc.subject Rosaceae en_US
dc.subject Ornamental en_US
dc.subject Evaluation en_US
dc.subject Foliar Assay en_US
dc.subject Inoculation en_US
dc.subject.lcsh Cotoneasters -- Disease and pest resistance en_US
dc.subject.lcsh Cotoneasters -- Genetics en_US
dc.subject.lcsh Fire-blight en_US
dc.title Genome sizing and fire blight resistance screening in Cotoneaster en_US
dc.type Thesis/Dissertation en_US
dc.degree.name Master of Science (M.S.) in Horticulture en_US
dc.degree.level Master's en_US
dc.degree.discipline Agricultural Sciences en_US
dc.degree.grantor Oregon State University en_US
dc.contributor.committeemember Mehlenbacher, Shawn A.
dc.contributor.committeemember Stockwell, Virginia O.
dc.contributor.committeemember Owen, James S.
dc.contributor.committeemember Lambert, Misty
dc.description.peerreview no en_us

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