Genetics and Genomics Commons^™

Resistance To Double-Stranded Rna (Dsrna) In Colorado Potato Beetle (Leptinotarsa Decemlineata Say): Genetic And Molecular Insights, Swati Mishra

Doctoral Dissertations

Double-stranded RNA (dsRNA) insecticides delivered through transgenic and non-transgenic means have been approved for commercialization in the US. As with other insecticides development of insect resistance is expected, necessitating the implementation of an Insecticide Resistance Management (IRM) framework for their long-term use. Laboratory-selected insect resistance strains can provide useful insights for an effective IRM plan. The Colorado potato beetle (CPB) is the target pest for the first commercial dsRNA foliar spray, making it an ideal model to study dsRNA resistance. In this dissertation, we studied the previously described CEAS 300 strain of CPB that exhibits >11,100-fold resistance against V-ATPase subunit …

Upland Cotton And Nematodes: An Analysis Of Historical Resistance, Upcoming Threats, And Co-Inoculation Effects, Amanda Gaudin

Theses and Dissertations

Upland cotton (Gossypium hirsutum ) is an important fiber crop grown throughout the southern United States. Plant-pathogenic nematodes are worm-like animals that feed on the roots of most agronomic crops, including cotton. The southern root-knot nematode (Meloidogyne incognita, RKN) and the reniform nematode (Rotylenchulus reniformis, RN) cause significant yield losses in cotton every year. Current sources of resistance are effective but limited, therefore historical screenings of cotton accessions were revisited in search for novel resistance sources. None were identified but many of the screened accessions possessed markers of known root-knot nematode and reniform nematode resistance. …

Compensatory Phenolic Induction Dynamics In Aspen After Aphid Infestation, Rajarshi Kumar Gaur, Ilka Nacif De Abreu, Benedicte Riber Albrectsen

Aspen Bibliography

Condensed tannins (CTs) are polyphenolics and part of the total phenolic (TP) pool that shape resistance in aspen (Populus tremula). CTs are negatively associated with pathogens, but their resistance properties against herbivores are less understood. CTs shape resistance to pathogens and chewing herbivores and could also shape resistance to aphids. Being chemical pools that are highly variable it can further be questioned whether CT-shaped resistance is better described by constitutive levels, by the induced response potential, or by both. Here, aspen genotypes were propagated and selected to represent a range of inherent abilities to produce and store foliar …

Effects Of Thinning On Dynamics And Drought Resistance Of Aspen-White Spruce Mixtures: Results From Two Study Sites In Saskatchewan, Philip G. Comeau

Aspen Bibliography

Drought stress associated with warm temperatures is causing increased mortality and reduced growth of trees in drier portions of the boreal forests of western Canada with both warming and drought expected to increase over the coming decades. While thinning is often shown to reduce drought stress, there is little information on its effects in stands comprised of mixtures of trembling aspen and white spruce that are common in the forests of this region. This study examined effects of pre-commercial thinning on aspen and spruce growth, response to drought stress, and stand dynamics for two study sites located in Saskatchewan, Canada. …

Geographic Distribution Of Bacillus Thuringiensis Cry1f Toxin Resistance In Western Bean Cutworm (Lepidoptera: Noctuidae) Populations In The United States, Brad S. Coates, Craig A. Abel, Katharine A. Swoboda-Bhattarai, Debra E. Palmquist, Débora Goulart Montezano, Sarah N. Zukoff, Yangzhou Wang, Jeffery D. Bradshaw, Christina D. Difonzo, Elson Shields, Kelley J. Tilmon, Thomas Hunt, Julie A. Peterson

West Central Research and Extension Center, North Platte

The western bean cutworm (WBC), Striacosta albicosta (Lepidoptera: Noctuidae), can be a severe pest of transgenic corn in the western Plains and Great Lakes regions of North America, including on hybrids expressing the Bacillus thuringiensis (Bt) Cry1F toxin. The level and geographic distribution of Cry1F resistance are not completely known. Neonate S. albicosta from 10 locations between Nebraska and New York state were subjected to dose–response trypsin-activated native Cry1F toxin overlay bioassays. In 2017, the mean estimated lethal concentration causing 50% larval mortality (LC50) ranged from 15.1 to 18.4 μg Cry1F cm−2, and were not significantly different among locations. In …

Breeding For Resistance In California Strawberry To Verticillium Dahliae, Zachary Christman

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

This article focuses on breeding resistant strawberries to the fungus Verticillium dahliae, common name Verticillium wilt. This is a serious fungal disease that can result in a loss of 50% or more of a strawberry harvest when grown in infested soil. The main goal is to provide an example of how a cultivar can be made more resistant to a plant pathogen with the use of plant breeding methods.

Since 1930 the University of California, Davis, has been developing strawberry cultivars that are adapted to the agricultural industry and regional farms. Developing cultivars that require fewer inputs are of …

Planting The Chalcone Reductase Family Tree: Identification And Characterization Of Chalcone Reductase Genes In Soybean, Caroline Julia Sepiol

Electronic Thesis and Dissertation Repository

Soybean (Glycine max [L.] Merr) is an important crop grown in Canada, generating $2.4 billion in sales. Though this number may be promising, soybean farmers lose about $50 million worth of yield annually due to root and stem rot disease caused by Phytophthora sojae. Many strategies have been developed to combat the infection; however, these methods are prohibitively expensive. A ‘cost effective’ approach to this problem is to select a trait naturally found in soybean that can increase resistance. One such trait is the increased production of root glyceollins. One of the key enzymes exclusively involved in glyceollin …

Characterization Of Resistance To The Cry1f Toxin From Bacillus Thuringiensis In Resistant Fall Armyworm, Spodoptera Frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) From Puerto Rico, Ana Maria Velez

Department of Entomology: Dissertations, Theses, and Student Research

Transgenic corn expressing Cry1F protein from Bacillus thuringiensis Berliner has been registered for Spodoptera frugiperda control since 2003. Unexpected damage to Cry1F corn was reported in 2006 in Puerto Rico and Cry1F resistance in S. frugiperda was documented. The inheritance of Cry1F resistance was characterized in a S. frugiperda resistant strain from Puerto Rico which displayed >387-fold resistance to Cry1F. Concentration-response bioassays of reciprocal crosses of resistant and susceptible parental populations indicated that resistance is recessive and autosomal. Bioassays of the backcross of the F₁ generation crossed with the resistant parental strain suggest that a single locus is responsible …