Call number: LD2668 .T4 1948 S34 / Master of Science

A comparative light and electron microscope technique has been used to study the cytological changes accompanying teliospore (i.e. probasidium) germination in Ustilago hordei (Pers.) Lagerh. Special emphasis has been placed on determining the ultrastructural events involved in karyokinesls, especially meiosis, and cytokinesis. The thesis is divided into five parts, of which the first is concerned with pre-germinal differentiation. The great increase in microanatomical complexity which occurs during the pre-germinal stages is due largely to an increase in the amount of endoplasmic reticulum (ER) and to the formation of "primary hydration vacuoles." Evidently the nuclear envelope gives rise to the new ER which in turn dilates to form the vacuoles. This is accompanied by an increase in mitochondrial size and the development of patches of patches of "flocculent cytoplasm." Part II concerns the initiation and subsequent extension of the metabasidium (i.e. promycelium). Initiation involves the localized degradation of the inner spore wall, and deposition of new wall material. The ER and spherosome-like bodies seem to be associated with these activities. Once spore wall rupture has occurred the structural basis of promycelial extension is unknown but changes in the number, size, and distribution of the spherosome-like organelles appear to have profound effects on the differentiation of the organism. Septation, knee-joint formation, and budding are discussed in part III. Elaborate membrane complexes are associated with cross wall initiation. A membranous plate is completed across the cell before septal wall thickening begins. The initiation of sporidia (i.e. basidiospores) involves a localized plasti-cization of the promyoelial wall followed by degradation of the old wall and subsequent synthesis of new wall material. Bridge-formation results when two adjacent cells give rise to bud-like processes which grow together and subsequently fuse to produce a protoplasmic bridge. The structure and activities of the metabasidial nuclei and their associated structures are discussed in part IV, Both meiosis and mitosis are unusual in that the two chromatin bodies apparently remain attached to the centriolar-kinetochore-equivalent and at least one of the chromatin bodies in attached to the nucleolus throughout the division cycle. The results are compatible with Brown and Stack's (1971) model for somatic nuclear division in some fungi. Membrane complexes, resembling those which Initiate septa, form in association with prophase nuclei and maintain a specific relation with the nucleus throughout division. In part V the suggestion is made that these complexes form part of a mechanism controlling the positional relationships of nuclear and cell divisions in the promycelium. / Science, Faculty of / Botany, Department of / Graduate

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Of the 372 chicks 35% showed smut. The P1 matings clean male X clean females gave 11.4% smutty progeny, clean male X smutty females gave 30.2% smutty progeny. The smutty male X clean females gave 45.2% while smutty male X smutty females gave 69.4% smutty progeny. Of the chicks that had black heads or necks 76% showed smut as adults, but there was no relationship found between shade or down and smut in adult undercolor. Chicks with black in wings gave 47.6% smutty adults, while only 19% of the non-black were smutty as adults. From the results obtained in this experiment smut depends upon two independent pairs or autosomal genes. At one locus there is "E" gene for the extension or black throughout the feathers, or "e", recessive allele which gives no color. At the other locus is gene "Y", for red color in the under-cola; or its recessive allele "y" which gives no color. Birds of genotypes Y/Y E/E, Y/Y E/e, Y/Y e/e, Y/y E/E, Y/y E/e, Y/y e/e, and y/y e/e give no smut. Those with genotypes y/y E/E and y/y E/e have smut. The amount of smut depends upon whether the gene "E" is in the E/E or E/e condition. Some chickens with genotype Y/y E/E may show smut since the epistatic condition is weakened when gene "Y" is in the heterozygous condition. Theoretically, the most desirable genotype for producers of broilers and processors would be y/y e/e since the under-color would be white. However, this is not the color called for in the Standard. Nevertheless, breeders should select that type of bird that will satisfy his customers. Selecting birds homozygous for "e" would be a breeder's best insurance against having smut. This, however, is not easy to do. Selecting for lighter colors, both surface and undercolor, would be the best way since black helps to make the shade somewhat darker. Lighter colored birds are not as likely to have "E" at all. It was noted in both field observation and actual experiment that those birds that had smut, laid fewer eggs during a seven month period. The P1 smutty females averaged 108.4 eggs; the P1 clean females averaged 130 eggs. The smutty females of the observed flock averaged 109 eggs; the clean females of the observed flock averaged 156 eggs. On the basis of this experiment and the author's field observation it is concluded that: 1. Smut in this strain of New Hampshires is caused by the interaction or two genes, one a recessive allele of "Y", red under-color, and the other a dominant allele "E", the extension ot black throughout the feathers, 2. Although a higher percent of those chicks showing black in the wings have smut as adults, one can't be sure whether smut will show or not. 3. A high percent or those chicks having black on head or neck will have smut as adults (76%). 4. Hens of this strain that have no smut will usually lay more eggs than smutty hens during a given period. 5. It is necessary to check for smut much more often than usually done to accomplish any great improvement. 6. Progeny testing is the best procedure to follow in attempts to control smut. / M.S.

Call number: LD2668 .T4 1963 H32 / Master of Science

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

The fungal disease smut (causal agent: Ustilago scitaminea H. & P. Sydow) and stalk borer Eldana saccharina Walker place major constraints on sugarcane agriculture in South Africa. The best approach for management is the introduction of resistant cultivars; however, conventional field-based screening for pest and disease resistance is a lengthy process. This study evaluated in vitro techniques combined with artificial inoculation of 12 week old in vitro plantlets and 8-10 week old embryogenic calli as rapid screening methods. Preliminary investigations were conducted on cultivars with known field ratings to smut and E. saccharina: NCo376, N26 and N39; and 5 „test‟ cultivars, whose identities were undisclosed until completion of experiments, were used to assess the accuracy of protocols. Infective U. scitaminea sporidia generated from teliospores, were used as inocula. Development of a callus protocol was unsuccessful due to sporidial and mycelial overgrowth, despite addition of a contact fungicide, Dithane M-45® (0.025 g/l) and a biocide/fungicide, PPMTM (5 ml/l), to media. Plantlet inoculation by injection, 1 cm above the apical meristem, resulted in 12% and 20% of smut susceptible NCo376 plantlets producing smut whips after 5 weeks when inoculated with 1 x 106 and 1 x 109 sporidia/ml, respectively. Smut whip production in 5 of the 8 (63%) cultivars inoculated with the lower sporidial concentration correlated with their field resistance ratings. In addition, whips harvested from in vitro plantlets were a valuable source of aseptic teliospores for future research. Ongoing work involves inoculation of NCo376 calli with such teliospores and maintenance on medium with PPMTM - emergence of whips from plantlets remains to be assessed. The E. saccharina screening protocol involved surface decontamination of eggs with 1% sodium hypochlorite (NaOCl) for 15 min. Feeding bioassays were conducted by placement of first instar larvae on in vitro plantlets and calli for 3 and 2 weeks, respectively. Larval mass, length and percentage infestation were recorded. Although greater larval size was expected in susceptible compared with resistant cultivars, the results did not support this. Significant differences in plantlet infestation were observed between susceptible (94-98%) and resistant (72-86%) lines. No significant differences were found in the callus feeding bioassay. However, a 24 h callus choice bioassay which investigated larval preference between callus genotypes compared with NCo376, showed significant differences and correctly discerned cultivar susceptibility according to field ratings. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2010.

Five potential resistance-inducing chemicals were applied to two sugarcane varieties (N12 and N27) in a pot trial with the aim of inducing resistance to nematodes in naturally-infested soil. BION® (acibenzolar-S-methyl), methyl jasmonate, cis-jasmone and 2,6-dichloroisonicotinic acid (INA) were applied as a foliar spray and suSCon® maxi (imidacloprid) applied to the soil. All chemicals were tested at two rates and plants were sprayed one week prior to being harvested at 7, 9 and 11 weeks of age. Meloidogyne and Pratylenchus infestation of sett and shoot roots was determined at each harvest. The activity of four pathogenesis-related proteins was examined at 7, 9 and 11 weeks using separate assays, these enzymes where chitinase, β-1,3-glucanase, peroxidase and polyphenol oxidase. Methyl jasmonate treatment produced significant increases in β-1,3-glucanase, chitinase and peroxidase activity. All other elicitor treatments showed little difference in enzyme activity from the Control. The effect of each treatment on plant growth was examined by recording the dried root and shoot biomass of each plant. No significant differences were seen (p<0.05; Holm-Sidak test). However, root and shoot dried biomass was highest in the N12 variety treated by suSCon® maxi. The infection of sugarcane with Ustilago scitaminea (sugarcane smut) is commonly identified visually by the presence of a smut whip. Identification of sugarcane smut infection can be determined prior to whip development by staining tissue sections with lactophenol cotton blue and examining plant tissues microscopically. This allows for a rapid determination of smut infection which can aid breeding programs. Smut infection is achieved in vitro by soaking sugarcane setts in smut spores collected from infected whips. Four methods of inoculation were examined. The method that most consistently caused infection involved allowing setts to germinate for 24 hours, before puncturing a bud with a toothpick, followed by submerging the sett in 1x10⁸ smut spores per mℓ. An elicitor of systemic acquired resistance called BION®, and an insecticide with resistance-inducing properties called Gaucho® (imidacloprid) were used as a sett soak treatments to induce resistance to sugarcane smut. The effect of each treatment at three concentrations on plant germination and growth was examined in the NCo376 variety. Smut spore germination on agar was examined in the presence of both treatments at three concentrations. Sugarcane setts were treated with a concentration that did not significantly reduce the germination of smut spores or sugarcane setts. Plants were infected with smut post treatment and allowed to grow for approximately one month until plants were between 8 and 10 cm in height. Smut infection was assessed by cutting longitudinal sections through the base of the shoot and staining each section with cotton blue lactophenol. Treatment with BION® and Gaucho® did not reduce smut infection. / M.Sc.Agric. University of KwaZulu-Natal, Pietermaritzburg 2013.