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Browsing by Author "Byrne, Patrick F., committee member"

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    Adaptability of oilseed species at high altitudes of Colorado and technology transfer to Afghanistan
    (Colorado State University. Libraries, 2012) Sediqi, Mohammad Navid, author; Johnson, Jerry J., advisor; Byrne, Patrick F., committee member; Jha, Ajay K., committee member
    To view the abstract, please see the full text of the document.
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    Characterization and molecular mapping of stripe rust resistance in a Denali/Hatcher winter wheat doubled haploid population
    (Colorado State University. Libraries, 2019) Afshar, Zaki, author; Haley, Scott D., advisor; Byrne, Patrick F., committee member; Broders, Kirk D., committee member
    The majority of global wheat (Triticum aestivum L.) production is subject to infection by the stripe rust pathogen (Puccinia striiformis Westend. f. sp. tritici Erikss.). The evolution of new stripe rust races appears to be occurring more rapidly than in the past, causing significant economic loss through yield reduction and increased use of fungicides. A combination of all-stage resistance and high-temperature adult plant (HTAP) resistance in new cultivars may provide complete resistance or serve to reduce disease incidence, thus providing a greater overall level of protection. In addition, knowledge of the form of resistance present in a particular cultivar may help to minimize fungicide use with cultivars that show early-season infections prior to initiation of HTAP resistance. A doubled haploid population (n=210) developed from a cross between winter wheat cultivars 'Hatcher' (PI 638512) and 'Denali' (PI 664256) was developed and characterized for response to stripe rust during 2018 and 2019 at Fort Collins, CO and Rossville, KS. A high density genetic linkage map consisting of 4,441 single nucleotide polymorphism markers derived via genotyping by sequencing was used to identify markers for stripe rust resistance in this population. Four quantitative trait loci (QTL) for infection type (IT) and disease severity (DS) (QYr.csu-1B, QYr.csu-3A, QYr.csu-3B, and QYr.csu-7B) were found to contribute to stripe rust resistance. Among the resistance QTL, QYr.csu-1B and QYr.csu-3A iii were the most consistent for single environments and combined across environments and accounted for 9.6-16.3% and 10.1-14.4% of phenotypic variation, respectively. QYr.csu-3B showed a stronger effect than QYr.csu-7B and was detected in more than one environment. Flanking markers for all the identified QTL, especially for QYr.csu-1B and QYr.csu-3A, will be useful to develop wheat cultivars with more effective and durable resistance to stripe rust.
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    Evaluation of plant characteristics and disease resistance in Cu-ipt transformed watermelon cv. crimson sweet
    (Colorado State University. Libraries, 2004) Goktepe, Fahrettin, author; Hughes, Harrison G., advisor; Byrne, Patrick F., committee member; Vivanco, Jorge M., committee member; Hill, Joseph P., committee member
    Watermelon cv. Crimson Sweet was transformed with the copper inducible isopentenyl transferase gene (Cu-ipt) via Agrobacterium mediated gene transformation process. The ipt gene governs the rate-limiting step in the cytokinin biosynthesis pathway. The transformants were confirmed via polymerase chain reaction (PCR) in the plant with ipt specific primers. Cu-ipt transformed plants were treated with copper sulfate at a concentration of 5, 10, or 50 μM copper sulfate to determine if the gene could be activated by copper at three levels. Transformed plants treated with copper sulfate differed in evaluated horticultural characteristics from those non-transformed as well as transformed plants not sprayed with copper sulfate. Delayed leaf senescence, increased chlorophyll content, reduced apical dominancy and released axillary buds were significantly different in Cu-ipt transformants compared to non-transformant plants. Significant reduction of seed number in watermelon fruit was also observed in copper sulfate treated Cu-ipt plants as compared to the non-transformant plants. Other than some slight alterations, elevated endogenous cytokinin level didn't cause major interference with transformants normal growth and development. The application of copper sulfate also induced resistance against Gummy Stem Blight disease in Cu-ipt transformants and their seedlings compared to the non-transformant plants.
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    Evaluation of spring wheat genotypic response to soil health promoting management practices
    (Colorado State University. Libraries, 2017) Junaidi, Fnu, author; Fonte, Steven J., advisor; Byrne, Patrick F., committee member; Paschke, Mark W., committee member
    Growing efforts to restore soil organic matter and overall soil health are likely to enhance soil biological communities and promote positive interactions between plants and soil communities. However, modern genotypes bred under intensive management practices may not be able to benefit fully from soil health promoting practices if they have lost their ability to effectively interact with key soil organisms. The purpose of this study was to explore this idea by studying how spring wheat genotypes with different breeding contexts and histories respond to improved soil health achieved via additions of organic matter and soil fauna. A greenhouse experiment with a full factorial complete randomized design was carried out at Colorado State University, Fort Collins, between June and November, 2016. The treatment factors included spring wheat genotype, as well as compost and earthworm additions. The genotypes included a wild ancestor of wheat, Aegilops tauschii, two older genotypes of spring wheat, Gypsum and Red Fife, and two near-isogenic modern genotypes, Scholar Rht2M and Scholar Rht2W, that differ only by the presence of the semi-dwarf allele Rht-D1b in ScholarRht2M. Each wheat genotype was grown in rootboxes (24.5 x 3.5 x 38.0 cm) that received either soils amended with composted manure or not, and with or without the addition of earthworms (two Aporrectodea caliginosa per box). Measurements included plant growth (heading date, number of tillers), biomass (aboveground and root biomass, root:shoot ratio), root morphology (root length and diameter), yield-related traits (number of seeds, seeds weight, average weight per seed, harvest index), nitrogen content (vegetative aboveground and grains), and nitrogen uptake. Findings indicate that interactions between genotypes and soil treatments were inconsistent, and the original hypothesis, that older wheat genotypes would show a greater response to improved soil biological conditions relative to newer genotypes, was not well supported. Overall, the aboveground and yield responses to compost were small compared to the root responses. Composted manure additions, increased root length, biomass, and diameter only in the wild accession (Ae. tauschii) and older Gypsum wheat variety. Modern genotypes, on the other hand, exhibited little root trait plasticity except in root diameter, which decreased with compost additions. Except for a decrease observed in Red Fife, compost effects on aboveground biomass were not significant for most genotypes. Genotype x earthworm interactions were only observed in the vegetative biomass N uptake, and earthworm effects in general were low due to low survival of the earthworms. Ae. tauschii and Gypsum had a more positive response to compost addition for both aboveground and root biomass, indicating that these genotypes may better take advantage of soil health promoting practices. While Gypsum had a similar response to the wild accession when compost was added, Red Fife tended to respond more like the modern genotypes. Overall, my findings suggest that different wheat genotypes can respond distinctly to changes in soil management and biological activity. Only a few genotypes were tested, but a number of clear genotype x soil biology interactions highlights the importance of considering soil management practices, environmental context, and breeding history for different wheat lines, so that we can better manage plant x soil interactions.
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    Inhibition of HT-29 colon cancer cell cultures by extracts from biodiverse germplasm sources of Solanum tuberosum L.
    (Colorado State University. Libraries, 2012) Zuber, Tatiana, author; Stushnoff, Cecil, advisor; Holm, David G., committee member; Byrne, Patrick F., committee member; Thompson, Henry J., committee member
    To view the abstract, please see the full text of the document.
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    Interspecific reproductive barriers in the tomato clade
    (Colorado State University. Libraries, 2011) Baek, You Soon, author; Bedinger, Patricia A., advisor; Stack, Stephen, committee member; Byrne, Patrick F., committee member
    Interspecific Reproductive Barriers (IRBs) preserve species identity by preventing interspecific hybridization, an essential facet of the biological species concept. Wild tomato species (Solanum sect. lycopersicum) are useful for studying interspecific reproductive barriers. Within the tomato clade there are 13 closely related species possessing diverse mating systems and complex IRBs. IRBs can be divided into two types: those occurring before mating (premating barriers) and those operating after mating (postmating barriers). Premating barriers include a variety of floral morphological characters correlated with a diversity of mating systems. Postmating barriers can be subdivided into prezygotic, those acting after mating but before fertilization, and postzygotic, those acting after fertilization. In the tomato clade, regulation of pollen tube growth in pistils constitutes postmating prezygotic barriers that are known to be important for preventing hybridization. Unilateral incongruity/incompatibility (UI), which prevents hybridization in one direction of an interspecific cross by inhibiting pollen tube growth in the pistil, is common in the tomato clade. Postzygotic barriers are also important as genetic isolating mechanisms resulting in failure of fruit or viable seed production in cases where prezygotic barriers are absent. In this study, I first examined the hypothesis of positive correlation between pollen grain size and style length among nine species in the tomato clade, because differences between species in pollen size and style length have been proposed to be a potentially important isolating mechanism between species, since larger pollen grains (containing more stored nutrients) may be needed to traverse longer styles. However, I found no correlation between pollen grain size and style length in the tomato clade, and therefore did not find this to be a likely isolating mechanism among the species in this study. Second, I examined UI barriers between species of domesticated tomato (self-compatible, SC) and three wild red-fruited SC species as pollen donors onto pistils of eight green-fruited species. Pistils of (self-incompatible) SI green-fruited species rejected pollen from all SC red-fruited species. However, pollen rejection and/or pollen tube growth of the three wild SC red-fruited species varied in pistils of green fruited SC species and SC populations of SI species. Finally, three types of IRBs including stigma exsertion, UI, and postzygotic barriers were investigated in 10 sympatric pairs of wild species. In these sympatric pairs, prezygotic and postzygotic barriers were found to prevent interspecific hybridization. This research will help elucidate the nature of reproductive barriers in wild populations. Studies of IRBs in tomato, a major food crop, also have potential for understanding reproductive barriers as they pertain to agronomic improvement.