Thesis (M.B.A.)--Boston University

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 127-141). Also available on the World Wide Web.

Graduation date: 1996

Viability and dispersal of ascospores of Anisogramma anomala, the cause of eastern filbert blight (EFB) on European hazelnut, from diseased branches pruned from trees were measured. In each of two years, branches bearing stromata of A. anomala were cut in mid-December and compared to branches cut near budbreak in March, when trees became susceptible to infection. The experiment was replicated three times at separated locations. At each location, 125 diseased branches (source) were piled loosely in a 1 x 1 m area. From March to June, spore traps (rain sampling-type) as well as 2-year-old potted hazelnut trees were placed next to each source, 6.4 m upwind and downwind, and 20 m downwind from each source. During seven significant major rain events over the two seasons, hazelnut seedlings (3-month-old) were placed adjacent to the spore traps. Near sources significantly higher (P. < 0.01) ascospores counts were obtained for branches cut near budbreak compared to those pruned in December in the first season; no significant difference in counts of ascospores were observed in the second season between pruning treatments. For both seasons significantly higher (P < 0.05) counts of ascospores were observed at 6.4 m downwind compared to 6.4 m upwind or 20 m downwind of a source. Ascospore viability, as assessed by staining with trypan blue, was similar for both pruning times at all distances and averaged 50%. At least one infected seedling was obtained for 5 of 7 major rain events regardless of pruning time at sources and 3 of 7 major rain events 6.4 m downwind of a source. All of the 2-year-old potted trees for both pruning treatments at the source and 6.4 m downwind became diseased and > 50% of trees at 20 m downwind became diseased in the 2010 season. Similar to ascospores counts, disease incidence was significantly higher (P < 0.01) in 2-year-old potted trees observed 6.4 m downwind compared to 6.4 m upwind or 20 m downwind in the 2010 season. Significantly higher (P < 0.01) disease incidence in 2-year-old potted trees was observed 20 m downwind compared to 6.4 m upwind in the 2010 season. Downwind disease gradients for both pruning treatments were shallow with slopes that were not significantly different than zero (p > 0.05) for the 2010 season. Based on these results, ascospores from diseased branches pruned from trees in both pruning treatments remained viable, infectious and were dispersed downwind of each treatment. / Graduation date: 2012

European hazelnut is a significant crop in the Pacific Northwest, and the US ranks 4th internationally for hazelnut production. Production in the Pacific Northwest is threatened, however, by the disease eastern filbert blight (EFB) caused by the fungus Anisogramma anomala (Peck) E. Müller. To meet the challenges faced by the hazelnut industry in Oregon and Washington, the breeding program at Oregon State University has focused on developing DNA marker technology and producing EFB resistant cultivars. This study focused on developing new microsatellite markers from hazelnut transcriptome sequences and on disease resistance from three accessions ('Culpla,' 'Crvenje,' and OSU 495.072) which showed no disease symptoms following a series of inoculations. DNA markers have been useful in hazelnut breeding for marker-assisted selection, construction of genetic linkage maps, cultivar fingerprinting, and phylogeny studies. Previously developed markers include AFLP, RAPD, ISSR, and microsatellite (SSR) markers developed from enriched libraries and ISSR fragments. This study utilized the transcriptome sequence from 'Jefferson' hazelnut to mine for microsatellites, align with the genomic sequence, design primers, screen for polymorphism, and characterize and map polymorphic markers. A total of 1432 microsatellites were mined from the transcriptome sequence, and the most frequently found motifs were AG (35.8%), AT (13.3%), and AAG (12.7%), and 382 primer pairs were designed. Screening showed that 119 markers were polymorphic, and these were characterized on sets of 50 and 14 accessions. Fifty-three markers that segregated in the mapping population or in three alternate populations were mapped and assigned to linkage groups. A dendrogram showed that accessions clustered mostly according to geographic origin. These results confirm the high level of diversity present in hazelnut, and the markers developed in this study will be useful for further genetics studies in hazelnut. The three EFB resistant parents 'Culpla,' 'Crvenje,' and OSU 495.072 were subjected to two inoculation treatments: greenhouse inoculations and exposure under an inoculation structure. The accessions remained free of disease after both treatments. Progeny segregating for resistance were produced. The progeny were inoculated either in the greenhouse or under the structure, and disease response recorded for each individual. DNA was extracted from seedlings, and sets of 32 seedlings from each resistant parent were screened with previously mapped markers using PCR and capillary electrophoresis. All three resistance sources were correlated with marker A614, allowing the resistance loci to be assigned to linkage group (LG) 6. The progeny were then screened with all known microsatellite markers on LG 6, and linkage maps constructed of the marker loci and resistance loci. Markers KG821, LG628, and LG696 are especially close to the resistance loci and will be useful for marker-assisted selection. Although these resistance loci are located in the same region of LG 6 as the 'Gasaway' resistance gene, they are different from 'Gasaway,' and markers linked to resistance will be useful for introgressing and pyramiding resistance in new cultivars. / Graduation date: 2013