Typescript (photocopy) / xiii, 223 leaves : ill., (part col.) ; 31 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Genetics, 1984

Thesis (Ph.D.) -- University of Adelaide, Dept. of Genetics, 1984. / Typescript (photocopy).

Thesis--University of Michigan, 1916. / "Reprinted from the American journal of botany, 4: 179-220, April, 1917." "Paper no. 156 from the Botanical Department of the University of Michigan." "Literature cited": p. 216-220.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1966. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 77-84).

Thesis--University of Michigan, 1916. / "Reprinted from the American journal of botany, 4: 179-220, April, 1917." "Paper no. 156 from the Botanical Department of the University of Michigan." "Literature cited": p. 216-220.

Rust fungi belonging to the order Uredinales have usually been considered the classical examples of obligate parasites amongst plant pathogenic fungi. The development of our knowledge of the metabolism, nutrition and physiology of the rust fungi has been restricted because of our inability to grow these fungi in axenic culture. In the past the physiological and biochemical investigations on rust fungi perse have been limited to studies of the germination and development of germ tubes. The cultivation invitro of Puccinia graminis tritici (Erikss . and .Henri.), Australian race ANZ 126-6,7, by Williams et al. (1966, 1967), together with the report of Turel (1969) on the axenic culture of Melampsora lini (Ehrenb) Lev, race 3 promoted research on culturing rust fungi on artificial medium. An artificial medium containing 3% glucose, Czapek's Mineral salts, 0.1% Evan's peptone, plus defatted BSA supported growth and sporulation of Puccinia graminis tritici race ANZ 126-6,7. Typical pigmented uredospores and teliospores were formed after 6-3 weeks growth. The uredospores were capable of infecting the mesophyll of wheat leaves exposed by stripping back the lower epidermis. Scanning electron microscopy revealed the presence of a coating of unknown chemical composition around the uredospores developed in vitro and not observed on uredospores grown on wheat leaves. Two different strains of Melampsoralini (Ehrenb) Lev were grown on solid media containing 4% sucrose, modified Knop's tissue culture macro nutrients, Berthelot's micro nutrients, yeast extract and peptone. The mycelium was generally binucleate. Spore-like structures were recorded in the stroma which resembled uredospores and teliospores . Addition of 1% defatted BSA to the medium described above greatly increased the frequency of establishment off lax rust colonies. A defined liquid medium, containing Czapek's minerals y Ca++, glucose, as particacid, glutathione and cysteine, and inoculated with uncontaminated uredospores, supported good vegetative growth and sporulation of wheat stem rust (Puccini agraminis f. sp. tritici race ANZ 1 2 6 - 6 , 7). Of six North American races of wheat stem rust fungus tested, only three grew vegetatively on artificial medium. Finally a chemically defined liquid medium containing sucrose , Knop's mineral salts, micro nutrients, aspartic (or glutamic) acid and cysteine supported the growth of vegetative colonies of Melampsora lini race 3 from uncontaminated uredospores in a highly reproducible manner. The formation of uredospores and telio spores of these colonies in the liquid medium was controlled by the level of Ca++ (as Ca(NO₃)₂) and the number of colonies per flask. With 60-70 colonies per flask, uredospore formation occurred on 60 to 70% of the colonies at a Ca++ level 8. 5 mM. A decrease in the Ca++ level to 4.5 mM or colony frequency to 10 per flask resulted in only in frequent sporulation vitro infected in tactcotyledons result with flax rust represents ability to control the growth of parasite in axenic culture. The uredospores produced in a normal manner. This a substantial advance in our this important obligate parasite in axenic culture. / Land and Food Systems, Faculty of / Graduate

Three hundred ninety one (391) spring wheat introductions from Asian, Middle Eastern and Mediteranean areas were screened for resistance to races C17, C20, C25, C49, C53 and C57 of Puccinia qraminis tritici; races 1, 5, 9, 15 and bulks 1, 4 and l0 of Puccinia recondita; races T2, T10, T13 and T39 of Ustilago tritici and to 6 isolates of Drechslera tritici-repentis prevalent in western Canada. Of the 34 introductions resistant to P. graminis tritici, 15 were genetically studied using F2 segregation data derived from the progeny of the crosses involving resistant introductions, their corresponding near isogenic lines and stem rust universal suscepts. Eleven of these were found to carry single Sr genes for resistance, notably, Sr30, Sr13 and Sr15. Of the 70 introductions resistant to P. recondita, 28 were studied and 9 were found to carry known Lr genes for resistance, notably Lr10 and the genes present in RL6057 and RL6061. Twenty two introductions are believed to carry either 1 or 2 unidentified dominant, recessive, partially dominant and/or complementary genes for resistance to either stem or leaf rust. Five introductions were immune and 6 highly resistant to the 4 races of U. tritici. Sixty-nine introductions were resistant to D. tritici-repentis . These were arbitrarily classified into 10 'phenotypic classes' according to their reactions to the 6 isolates used.

Three hundred ninety one (391) spring wheat introductions from Asian, Middle Eastern and Mediteranean areas were screened for resistance to races C17, C20, C25, C49, C53 and C57 of Puccinia qraminis tritici; races 1, 5, 9, 15 and bulks 1, 4 and l0 of Puccinia recondita; races T2, T10, T13 and T39 of Ustilago tritici and to 6 isolates of Drechslera tritici-repentis prevalent in western Canada. Of the 34 introductions resistant to P. graminis tritici, 15 were genetically studied using F2 segregation data derived from the progeny of the crosses involving resistant introductions, their corresponding near isogenic lines and stem rust universal suscepts. Eleven of these were found to carry single Sr genes for resistance, notably, Sr30, Sr13 and Sr15. Of the 70 introductions resistant to P. recondita, 28 were studied and 9 were found to carry known Lr genes for resistance, notably Lr10 and the genes present in RL6057 and RL6061. Twenty two introductions are believed to carry either 1 or 2 unidentified dominant, recessive, partially dominant and/or complementary genes for resistance to either stem or leaf rust. Five introductions were immune and 6 highly resistant to the 4 races of U. tritici. Sixty-nine introductions were resistant to D. tritici-repentis . These were arbitrarily classified into 10 'phenotypic classes' according to their reactions to the 6 isolates used.

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is an economically important foliar disease of wheat (Triticum aestivum). In the last decade, losses from stripe rust in North Dakota (ND) have increased, peaking at 5% in 2015. Three research studies were conducted to address questions on the pathogen, varietal resistance, and integrated management. The objective of the first study was to (i) identify virulent phenotypes of Pst isolates collected from ND from 2015 to 2017 and assign races, and (ii) determine the effect of temperature on in vitro urediniospore germination, latency, and lesion spread. Across the three years, five races were detected with PSTv 37 being the most common. The highest urediniospore germination occurred at 12oC followed by 16oC. Pst isolates had shorter latency at 21oC and larger lesion spread at 16oC. The objective of the second study was to evaluate seedling resistance and adult plant resistance in the North Dakota State University spring wheat breeding program using races PSTv 37 and PSTv 52. Results from seedling experiments indicated only four and two lines were resistant to PSTv 52 and PSTv 37, respectively. Adult plant resistance experiments were unsuccessful in 2019, and will be conducted again in the future. The objective of the third study was to develop fungicide timing recommendations for wheat rust (stripe and leaf) based on varietal resistance and time of disease onset. Rust developed in five of the eight field trials, and timing of disease onset was categorized by growth stage (tillering, flag leaf, or early-flowering). Results indicated fungicide application timing was influenced by timing of disease onset and varietal resistance. When rust was detected at the tillering growth stage on the susceptible variety, the best time to apply a fungicide was at Feekes 9. When rust was detected at flag leaf or beyond on a susceptible variety, a fungicide application at Feekes 10.51 provided the adequate disease reduction and protection of yield. Results from these research studies provide a better understanding of Pst, determined seedling resistance in the breeding program, and provides field data to refine management recommendations for wheat rusts in ND. / North Dakota Wheat Commission / State Board of Agricultural Research and Education