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Item Impacts of Soybean Cyst Nematode (Heterodera Glycines) on Sugarbeet (Beta Vulgaris) and Interactions with Rhizoctonia Solani(North Dakota State University, 2014) Rudolph, Kurt DonaldSoybean cyst nematode (SCN), Heterodera glycines is in the same genus as the sugarbeet cyst nematode (SBCN) Heterodera schachtii, there has been concern that SCN could also penetrate sugarbeet roots. The objectives were: 1) determine if SCN eggs hatch in the presence of sugarbeet seedlings and the larvae penetrate the roots, 2) determine at what age sugarbeet seedling are most susceptible to SCN penetration, 3) determine if SCN can penetrate sugarbeet roots under field conditions and 4) and determine if SCN could increase incidence of Rhizoctonia root rot in sugarbeet seedlings. This study demonstrated that SCN can penetrate the roots of a variety of sugarbeet. The results from the field demonstrated that SCN could penetrate sugarbeet seedlings under normal field growing conditions, and that penetration occurred in both SBCN susceptible and resistant sugarbeet cultivars. Penetration by SCN increased sugarbeet seedling root damage by R. solani under controlled conditions.Item Biology and Management of Fusarium Species on Sugar Beet(North Dakota State University, 2017) Lai, XiaoMinnesota and North Dakota together produce about 51% of the beet sugar in the United States of America. Fusarium diseases caused by Fusarium oxysporum f. sp. betae and F. secorum on sugar beet cause significant reduction in both root yield and sucrose concentration. This research was conducted to determine the best inoculation methods to induce Fusarium diseases on sugar beet seeds and plants and to evaluate fungicides for their efficacy at controlling Fusarium diseases in greenhouse conditions. The use of Fusarium colonized barley seeds in close proximity to sugar beet seeds and seedlings caused similar level of disease severity as the standard root-dipping method, and reduced the time for evaluation by directly inoculating seeds and 4-leaf stage plants rather than using older plants which have to be transplanted into new pots. Pydiflumetofen and metconazole fungicides used in-furrow have the potential to provide effective control of Fusarium diseases on sugar beet.Item Characterization of Effector Encoding Genes from the Novel Sugar Beet Pathogen Fusarium Secorum(North Dakota State University, 2015) Bian, ZhuyunA new disease of sugar beet, named Fusarium yellowing decline, was recently found in in the Red River Valley of MN and ND. This disease is caused by a novel pathogen named Fusarium secorum. Pathogens such as F. secorum secrete proteins during infection called ‘effectors’ that help establish disease. Since pathogenicity and disease development may depend on effector proteins produced by F. secorum during infection, effector protein identification furthers our understanding of the biology of this important pathogen. A list of 11 candidate effectors was generated previously. In this study, to characterize putative effectors, we developed a transformation system using polyethylene glycol–mediated transformation. Several mutant lines were created with an effector deleted from the genome using a split-marker knock-out strategy. To explore their role in pathogenicity, mutant strains have been inoculated to sugarbeet and compared to WT F. secorum.Item Identification and Characterization of Novel Cercospora beticola Necrosis-Inducing Effectors(North Dakota State University, 2021) Hamilton, Olivia GraceCercospora beticola is a hemibiotrophic fungus responsible for Cercospora leaf spot disease of sugar beet (Beta vulgaris). Plant pathogens such as C. beticola utilize “effector” molecules to aid in disease establishment. Effectors are generally small, secreted molecules that contribute to pathogen virulence. A culture filtrate infiltration study was conducted to identify potential effector molecules secreted by C. beticola. A variety of fungal growth conditions were pursued, one of which resulted in a necrotic phenotype when the culture filtrate was infiltrated into sugar beet leaves. The culture filtrate was fractioned using ion-exchange chromatography. Fractions were infiltrated to identify the protein responsible for necrosis. Five candidate necrosis-inducing effector proteins were identified through mass spectrometry analysis. Targeted gene disruption of these candidates and subsequent virulence assays revealed an increased virulence for Δ05663 strains compared to the inoculated wild-type. Full characterization of this candidate effector will shed light on the C. beticola-sugar beet interaction.Item Augmenting Fungicidal Activity of Tetraconazole with Chemosensitization Agents for Cercospora Leaf Spot Management(North Dakota State University, 2017) Metz, Nicholas JamesCercospora beticola (Sacc.) is the causal agent of Cercospora leaf spot (CLS). CLS is considered to be one of the most destructive foliar diseases of sugar beet in the world. CLS is managed in part through resistant cultivars, crop rotation, and cultural practices, but timely fungicide applications are necessary to manage disease effectively. Heavy reliance on fungicides to manage CLS has led to the development of resistance to multiple classes of fungicides. The most widely used class of fungicides is the demethylation inhibitors (DMIs). DMI-resistant C. beticola isolates have been increasing in incidence over the past decade. Chemosensitization agents (CAs) are compounds that have little to no antifungal activity, but may increase efficacy of commercial fungicides when co-applied. CAs could lead to better management of CLS and reduced production costs.Item Seed to Seedling Transmission of Colletotrichum lindemuthianum in Dry Edible Pinto Bean(North Dakota State University, 2015) Halvorson, Jessica MarieDry bean anthracnose, caused by Colletotrichum lindemuthianum, is a damaging disease that can cause significant reductions in seed quality and yield. The purpose of this study was to determine the races of C. lindemuthianum isolates collected in North Dakota and to develop a real-time qPCR assay to quantify the pathogen in seed and stem tissue. Race 73 continues to be the most common in North Dakota across 33 isolates collected in 2012. The qPCR assay using primer pair ClF1527/ClR1609 was proven useful for quantifying C. lindemuthianum, and was more specific than a previously developed method. Results from greenhouse and field studies indicated that as seed infection increased, emergence decreased and foliar symptoms and pathogen detection increased. Additionally, field studies demonstrated daughter seed infection increased and yield decreased as seed infection severity increased. Using primer pair ClF1527/ClR1609, the pathogen was detected ten days after planting in greenhouse and field studies.Item Characterization and Detection of Bacterial Pathogens of Common Bean(North Dakota State University, 2022) Nelson, KatieCommon bacterial blight (CBB) (Xanthomonas axonopodis pv. phaseoli (Xap) and X. fuscans pv. fuscans (Xff), halo blight (Pseudomonas savastanoi pv. phaseolicola (Psp)), and bacterial brown spot (P. syringae pv. syringae (Pss)), are yield-limiting diseases of common bean in North Dakota and Minnesota. The objectives of this research were to optimize a multiplex quantitative PCR (qPCR) assay for rapid detection and quantification of four bacterial pathovars in common bean seed, leaf, and pod tissue; determine the aggressiveness of Xap and Xff isolates; and determine the race types of Psp isolates in North Dakota and Minnesota. A fourplex qPCR assay was optimized, and novel primers and probe were designed for pathovar-specific detection of Pss. Significant differences were observed in Xap/Xff aggressiveness across isolates evaluated and in susceptibility of the differential lines (P <.0001). The 60 Psp isolates were identified as Race 6, the predominant race in the region.Item Genetically Dissecting the Recessive Rpg4-Mediated Wheat Stem Rust Resistance Locus in Barley(North Dakota State University, 2014) Arora, DeepikaThe rpg4-mediated resistance locus (RMRL) in barley provides recessive resistance against wheat stem rust (Puccinia graminis f. sp. tritici) races including the virulent race TTKSK (a.k.a Ug99). Three genes (HvAdfF3, Rpg5, and HvRga1) at the RMRL are required together for resistance. Allele characterization of these three genes identified the dominant rye stem rust resistance gene Rpg5 gene as the polymorphic R-gene conditioning the recessive rpg4-mediated wheat stem rust resistance. The Rpg5 gene contains an atypical R-gene structure encoding a nucleotide-binding site, leucine rich repeat, and serine/threonine protein kinase (STPK) domains. Genetic analysis of crosses between the resistant cultivar Q21861 with a functional Rpg5 allele and different susceptible varieties determined that most susceptible cultivars contain the susceptibility gene HvPP2C.1 in place of Rpg5 STPK domain. Genetic analyses determined that HvPP2C.1 conditions the recessive nature of the reaction, possibly negatively regulating the signaling pathway initiated by the Rpg5 kinase domain.Item Genetics of the Host-Pathogen Interaction in the Barley-Net Form Net Blotch System(North Dakota State University, 2017) Koladia, Vaidehi MohitPyrenophora teres f. teres is a fungal pathogen that causes barley net form net blotch. To evaluate the genetics of resistance in barley, a RIL population was developed using resistant barley lines CI5791 and Tifang and tested against a global collection of nine P. teres f. teres isolates. QTL analysis indicated that CI5791 resistance mapped to chromosome 6H and was effective against all isolates. Additionally, CI5791 harbored resistance on chromosome 3H effective against two Japanese isolates. Tifang also had resistance that mapped to 3H and was effective against four of the isolates. To evaluate the genetics of virulence in P. teres f. teres, a fungal population was developed and evaluated against ten barley lines. 19 unique QTL were identified on 12 different linkage groups. 1 or 2 major loci were identified for a few of the barley lines whereas for most lines, virulence was contributed by several loci.Item Spatial and Temporal Sensitivity of Alternaria Species Associated with Potato Foliar Diseases to Demethylation Inhibiting and Anilino-Pyrimidine Fungicides(North Dakota State University, 2015) Fonseka Gunawardena, Arthur Dimitri LakshanEarly blight and brown spot, caused by Alternaria solani and Alternaria alternata, respectively, are important foliar diseases of potato, affecting both tuber yield and quality. Most of the commercial cultivars lack resistance; therefore, application of foliar fungicides remains a primary management strategy. Correlation coefficients comparing EC50 values for conidial germination and mycelial growth of A. solani and A. alternata in response to boscalid and fluopyram, respectively, were low, indicating that the association between these two in vitro assays was very weak. Baseline sensitivities of Alternaria spp. to difenoconazole, metconazole, and pyrimethanil using mycelial growth assays demonstrated high intrinsic activity against the two pathogens. Six out of 245 A. solani isolates exhibited reduced-sensitivity to pyrimethanil in in vitro assays and reduced-sensitive isolates were not controlled except at 100 μg/ml in greenhouse efficacy tests. The DMI chemistries and pyrimethanil remain valuable options for fungicide rotation programs in areas of high disease pressure.