The sudden oak death pathogen, Phytophthora ramorum, is present in southwestern Oregon, and while an eradication effort is underway, the potential impact of the polyphagous pathogen on surrounding vegetation is unknown. Plant communities in the area are substantially different from those affected in California, although tanoak (Lithocarpus densiflorus), evergreen huckleberry (Vaccinium ovatum) and Pacific rhododendron (Rhododendron macrophyllum) are hosts found in both areas. Other species are likely to be susceptible to the pathogen. Detached leaf and whole plant assays were used to test species commonly associated with tanoak, as well as three rare or endemic ericaceous species of the western Siskiyou Mountains and their associated taxa. Leaves and plants were challenged with zoospore suspensions that were capable of generating symptoms in the known hosts tanoak and evergreen huckleberry. Most (78%) of the previously unchallenged species developed necrotic lesions in detached leaf assays although severity (% leaf area necrotic) was variable. All three of the ericaceous species of conservation concern: Arctostaphylos hispidula, Kalmiopsis leachiana, and Leucothoe davisiae were susceptible in detached leaf assays. Factors important in determining whether or not these species will become infected in their native habitat are discussed. / Graduation date: 2004

Random amplified polymorphic DNA (RAPD) markers were used in three genetic studies in lentil (<i>Lens culinaris</i> Medikus). The first study involved development of RAPD markers linked with genes for resistance to ascochyta blight, caused by <i>Ascochyta fabae</i> f. sp. lentis Gossen et al. Seventy F₂-derived F₃ (F_2:3) lines were field screened for ascochyta blight reaction in each of two hybrid populations, Indianhead x Eston and ILL 5588 x Eston, that were segregating for resistance to ascochyta blight. Resistance to ascochyta blight in ILL 5588 lentil was conferred by a single dominant gene (<i>Ral₁</i>), whereas resistance in Indianhead lentil was conferred by a single recessive gene (<i>ral₂</i>). An efficient DNA extraction procedure and a PCR protocol that yielded RAPD markers with high resolution were developed for lentil. Bulked segregant analysis was used to produce four bulks of DNA from resistant vs. susceptible F₂ plants in each of these two populations which were then screened for RAPD markers using 400 random oligonucleotide primers. One RAPD marker, UBC227₁₂₉₀, was linked to the recessive gene, <i>ral₂</i>, in Indianhead lentil in repulsion phase with a map distance of 14.1 ± 4.5 cM. No RAPD marker was linked with the <i>Ral₁</i> gene in ILL 5588 lentil. In the second study, RAPD markers were used to study phylogeny of the genus Lens. DNA, extracted from 23 accessions of all five taxa of the genus Lens (culinaris, orientalis, nigricans, odemensis and ervoides), was screened for RAPD polymorphisms, using 11 random oligonucleotide primers. Two accessions of the differentiated cytotype of L. nigricans were also included. One hundred and forty eight polymorphic RAPD markers were resolved. A dendrogram for these RAPD markers, using the unweighted pair group method, clearly separated all accessions into their supposedly related taxa. Lens orientalis was the undisputed progenitor of the cultivated lentil, <i>Lens culinaris</i>. A low level of RAPD polymorphism was observed in <i>Lens culinaris</i> and L. ervoides. The differentiated cytotype of L. nigricans was well separated from the normal cytotype of L. nigricans and was closely associated with the L. odemensis accessions, indicating its close genetic similarity to L. odemensis. Principal component analysis (PCA) also indicated a similar relationship among these accessions, but resulted in a better resolution of the groupings. In the third study, the genetic polymorphism of seven Canadian lentil cultivars were studied using RAPD markers. Four lentil cultivars, CDC Gold, CDC Matador, Eston and Indianhead each had a unique, cultivar-specific RAPD marker, allowing their identification.

No description available.

A new, uncomplicated system for the forced ventilation of plants and cultures has been investigated in terms of both its efficiency of ventilation and its effects on the growth and physiology of various plant species, including cauliflower, tobacco, Annona (custard apple) and potato. This new system, which has no moving parts or artificial energy requirement, provides a sustained, pressurised stream of sterile, humidified air (RH = 70-94%) driven by humidity-induced diffusion. This process depends upon the maintenance of a gradient of water vapour across a microporous partition for inducing the diffusion of air into the apparatus. Flows up to 5 cm³ min¯¹ can be produced and the atmosphere in a 60 cm³ culture vessel can be renewed every 12 min Compared to the standard conventional diffusive method of ventilation, e. g. by capping the vessel with a polypropylene disc, this new system has proved to be 18X more efficient in removing accumulated ethylene and in keeping CO₂ and O₂ levels in culture vessels close to atmospheric. This forced ventilation system has also been shown to be very effective in the in vitro cultivation of seedlings or cuttings of cauliflower, tobacco, Annona and potato for improving growth and preventing symptoms of vitrification such as leaf epinasty, reduction of leaf area and production of abnormal stomata. In potato cuttings the induction and production of microtubers have been promoted and the growth of abnormal callus prevented. In Annona cuttings flower bud production, leaf and shoot growth and micropropagation have been promoted and leaf and flower bud abscission have been reduced. In cauliflower, tobacco and Annona the leaf chlorophyll contents, rates of photosynthesis and yields were improved by this forced ventilation. These beneficial effects have been variously attributed to the efficient removal of ethylene, the maintenance of near to atmospheric levels of CO₂ and O₂ by day and night and to the reduction of humidity levels in the vessels to below 100% RH. It is hoped that this new ventilation system, which is comparatively inexpensive and requires very little maintenance might have some useful applications in the field of tissue culture and perhaps particularly in developing countries.

Thesis (Ph. D.)--University of Adelaide, Dept. of Crop Protection, 1996. / Includes bibliographical references (leaves 207-220).

Thesis (M.S.) in Plant, Soil and Environmental Sciences--University of Maine, 2008. / Includes vita. Includes bibliographical references (leaves 88-93).

Thesis(Master)--İzmir Institute of Technology, İzmir, 2005 / Keywords: Tomato, pepper, cucumber mosaic virus, resistance, genetic mapping. Includes bibliographical references (p.49-55)

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 147-167). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 147-167). Also available on the Internet.

Thesis (Ph.D.)--University of Western Australia, 2008.