Dissertation (PhD)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Made available in DSpace on 2014-06-11T19:28:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-06-20Bitstream added on 2014-06-13T18:35:02Z : No. of bitstreams: 1 silvajunior_taf_me_botfca.pdf: 480549 bytes, checksum: f7d5fb8db585125d630421fa598b3be8 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Recentemente, em dois campos comerciais de tomateiro dos tipos Salada e Italiano, localizados respectivamente em Bragança Paulista e Mogi Guaçú, SP, foram observados sintomas de queima generalizada nas folhas. Em observações ao microscópio óptico de tecidos infectados foi constatada a presença de exsudação bacteriana. Isolamentos realizados em meio de cultura permitiram obter bactérias com formato bastonete, Gramnegativas, com colônias de coloração branca e produtoras de pigmento fluorescente em meio B de King. Isolados bacterianos foram submetidos a testes bioquímicos e fisiológicos, entre eles, LOPAT, sendo enquadrados no grupo III de LOPAT (- + - - +) e, portanto, identificados como sendo Pseudomonas cichorii. Esses resultados foram corroborados por testes serológicos de imunofluorescência indireta, com antissoros produzidos para isolado tipo de P. cichorii. Esta bactéria causa doença em várias culturas de importância econômica e ainda não havia sido constatada em nosso país, na cultura do tomateiro. Isolados bacterianos encontramse depositados na Coleção de Culturas de Fitobactérias do Instituto Biológico, sob os números de acesso IBSBF 2309 e IBSBF 2323. Foram desenvolvidos também estudos visando a determinação da gama de hospedeiras e a reação de 28 genótipos de tomateiro aos isolados de P. cichorii. Plantas de abobrinha, alface, beldroega, berinjela, beterraba, cenoura, couvebrócolo, datura, fumo, girassol, jiló, melão, pepino, petúnia, pimentão, rabanete, repolho, rúcula, salsa e tomateiro, no estágio de um par de folhas verdadeiras, foram inoculadas por pulverização com os isolados IBSBF 2309 e IBSBF 2323 e um isolado de P. cichorii de girassol (GIR-1). Os isolados IBSBF 2309 e IBSBF 2323 mostraram-se patogênicos à beldroega, à datura, ao girassol, ao pimentão e ao tomateiro, enquanto que o isolado de girassol foi... / Recently, generalized blight symptoms were observed in tomato leaves of the Salada and Italiano types, in two commercial fields located, respectively, in Bragança Paulista and Mogi Guaçú, SP, Brazil. The presence of bacterial exudation was verified in observations of infected tissues under the optical microscope. Rod-shaped, Gram-negative bacteria were obtained from isolations in culture medium; the colonies were white and produced fluorescent pigment in King's B medium. Bacterial isolates were submitted to biochemical and physiological tests, including LOPAT, and were classified into LOPAT group III (- + - - +); consequently, they were identified as Pseudomonas cichorii. These results were corroborated by indirect immunofluorescence tests, using antisera produced for the type isolate of P. cichorii. This bacterium causes diseases in several crops of economic importance and had not yet been observed in tomato in Brasil. Bacterial isolates were deposited in Phytobacteria Culture Collection of Instituto Biológico, under accession numbers IBSBF 2309 and IBSBF 2323. Studies were also carried out in order to determine the host range and reaction of 28 tomato genotypes to P. cichorii isolates. Caserta pumpkin, lettuce, purslane, eggplant, beet, broccoli, carrot, Jimson weed, sunflower, tobacco, scarlet eggplant, melon, cucumber, petunia, green pepper, radish, cabbage, arugula, parsley, and tomato plants, all with one pair of true leaves, were spray-inoculated with isolates IBSBF 2309 and IBSBF 2323 and one P. cichorii isolate from sunflower (GIR-1). Isolates IBSBF 2309 and IBSBF 2323 were pathogenic to purslane, Jimson weed, sunflower, green pepper, and tomatoe, while the sunflower isolate was only pathogenic to purslane, Jimson weed, and sunflower, but not to green pepper or... (Complete abstract click electronic access below)

M.Sc. / A phytotoxic protein-lipopolysaccharide complex (PLPC) was isolated from 7 day old culture filtrates of Verticillium dahliae. The complex was purified to electrophoretic homogeneily by means of acetone precipitation, gel, chromatography and preparative agarose electrophoresis with a yield of 4.5 mg PLPC per litre culture filtrate ...

Pumkin seedlings (Cucurbita maxima) were inoculated with the fungus Sclerotinia sclerotiorum (Lib.) de Bary. Center regions of non-infected and infected cotyledons of various lengths were cut into 1 x 2 mm strips and processed for ultrastructural investigations. Complementary portions of opposing non-infected cotyledons were also processed as control tissue, and contained fewer storage products in cells than cotyledons of comparable size from non-infected plants. Young non-infected cells contained distinct lipid bodies, protein bodies and electron dense inlusions which were translocated out of older cells by abundant plasmodesmata. Initally, infected cells became plasmolyzed, followed by breakdown of the cytoplasm. Host cells were generally affected only 4-6 cells from the infection front. Many infected cells had abundant rough endoplasmic reticulum and all organells were eventually completely disrupted. Action of enzymes from fungal cells did not appear to be limited to the area immediatedly adjacent to hyphal cells.

No description available.

No description available.

Bibliography : leaves 92-99. / v, 99, [37] leaves, [14] leaves of plates : ill. ; 30 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 Biochemistry, 1992

Sphaeropsis sapinea and Diaporthe ambigua are important pathogens of forest and orchard tree species, respectively. Some isolates of S. sapinea are co-infected with two dsRNA viruses, SsRVl and SsRV2. Isolates of D. perjuncta (formerly thought to be D. ambigua) are infected with a positive-stranded RNA virus known as DaRV. While S. sapinea is. infected with a heterogeneous mixture of dsRNA elements of different sizes, D. perjuncta is infected with a single virus. This presents excellent opportunity for biocontrol of Diaporthe. The aim of this study was to assess these three viruses for possible application as biological control agents of S. sapinea and D. ambigua. This was' done by transfecting these with in vitro-produced RNA from the cloned viral genomes and assessing the pathogenicity of the transfected isolates on apples and apple trees. Attempts to transfect S. sapinea spheroplasts with SsRVl and SsRV2 failed. Co¬transfection of S. sapinea spheroplasts with both viruses also failed. Three isolates of D. ambigua and a single isolate of a Phomopsis sp. were successfully transfected with DaRV. Attempts to transfect the same fungi with a mutant of DaRV, bearing six codons for histidine immediately downsteam of an AUG thought to be a start codon for the translation of ORFl, failed. DaRV was originally thought to be isolated from D. ambigua. The fungal isolates transfected with DaRV were thought to be D. ambigua. The transfectants did not resemble the naturally-infected isolate. The ITS regions from the ribosomal DNA operon of these isolates were amplified using ITS 1 and ITS4 primer pair. The blast search revealed that the ITS sequence of the naturally-infected isolates are identical to D. perjuncta. One virus-free isolate was identified as a Phomopsis sp. while three other virus-free isolates were identified as D. ambigua. A PCR-based RFLP was developed to differentiate the naturally-infected D. perjuncta isolates from the virus¬free Phomopsis sp. and D. ambigua isolates. In the growth and pathogenicity studies, a DaRV-transfected, wild-type and negative control isolate of one Phomopsis and three D. ambigua isolates, were used. The DaR V -transfected Phomopsis sp. had a higher growth rate than the wild-type isolate. This DaRV-transfected Phomopsis sp. was more virulent on apples than the wild-type isolate. The wild-type isolate was slightly more virulent than the DaR V -transfected Phomopsis sp. on apple trees. There were no significant differences in growth rates between the DaRV-transfected and wild-type isolates of D. ambigua CMW5587 and D. ambigua CMW5287. There were no significant differences in virulence on apples between the DaRV-transfected and wild-type isolates of these fungi. The DaRV-transfected D. ambigua CMW5287 was more virulent than the wild-type isolate on apple trees. The DaRV-transfected D. ambigua CMW5587 had the same virulence as the wild-type isolate on both apples and apple trees. The DaRV-transfected D. ambigua CMW5288 had a slower growth rate than the wild-type isolate. There were no significant differences in virulence on apples between these isolates. The wild-type isolate of this isolate was significantly more virulent on apple trees than the DaRV-infected isolate. Although transfection was successfully done, the effects of DaRV on the Phomopsis sp. and D. ambigua isolates are not conclusive. In order to obtain conclusive results, virus-free isolates of D. perjuncta must be transfected. During the course of this study, there were no available virus-free isolates of this fungus. / Dissertation (PhD)--University of Pretoria, 2006. / Genetics / Unrestricted

Thesis (MSc)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: Grapevine trunk diseases are caused by invasive pathogens that are responsible for the slow decline of vines. In particular, Eutypa dieback of grapevine has had a devastating impact on vineyards worldwide, reducing growth and yield, eventually killing the grapevine. The causal organism of Eutypa dieback was first described as Eutypa armeniacae Hansf. & Carter, the pathogen that causes dieback of apricots, but since 1987 this species has been considered a synonym of Eutypa lata (Pers.:Fr.) Tul & C. Tul (anamorph Libertella blepharis A. L. Smith). Recently, it was proposed that at least two species that are capable of infecting grapevines are responsible for Eutypa dieback. Consequently, the molecular identification and characterisation of Eutypa dieback was used to delineate the species occurring on infected grapevines in South Africa. This involved the molecular analyses of three molecular markers, namely, the internal transcribed spacer (ITS) and large subunit (LSU) regions of the ribosomal DNA operon, and the -tubulin gene. The results obtained revealed the presence of a second species, namely, Eutypa leptoplaca (Mont.) Rappaz, that occurred together with E. lata on infected grapevines. Also co-habiting with these pathogens were related fungi form the Diatrypaceae family, Cryptovalsa ampelina (Nitschke) Fuckel and Eutypella vitis (Schwein.) Ellis & Everhart. Pathogenicity tests conducted on isolates representing C. ampelina, E. lata, E. leptoplaca, and E. vitis revealed that all were pathogenic to grapevine. Several species of Botryosphaeriaceae that commonly invade the woody tissue of grapevines are also pathogenic to grapevine. The symptoms in grapevine commonly associated with Botryosphaeriaceae are easily confused with the symptoms produced by Eutypa dieback which prompted the need for the development of a detection method that can correctly identify the presence of multiple pathogens. A reverse dot blot hybridisation (RDBH) method was subsequently applied to provide a rapid, accurate and reliable means of detecting the Eutypa species involved in the Eutypa disease complex, as well as those species of Botryosphaeriaceae known to cause disease in grapevines. The method involved the use of multiplex PCR to simultaneously amplify and label the regions of DNA that are used as pathogen specific probes. Consequently, membrane immobilised species-specific oligonucleotides synthesised from the ITS, - tubulin and LSU molecular data were evaluated during the application of this diagnostic method to detect Eutypa species. It was found that the species-specific oligonucleotides, designed from ITS sequence data, could consistently detect E. lata and E. leptoplaca. The application of the RDBH method for the detection of these Eutypa species, based on -tubulin and LSU sequence data, however, proved to be unsuccessful. Subsequently, a RDBH method, utilising species-specific oligonucleotides designed from elongation factor-1α sequence data, was successfully applied for the detection of Botyrosphaeria dothidea (Moug.:Fr.) Ces. & De Not., Neofusicoccum luteum (Pennycook & Samuels) Crous, Slippers & A.J.L. Phillips, Neofusicoccum parvum (Pennycook & Samuels) Crous, Slippers, A.J.L. Phillips and Neofusicoccum ribis (Slippers, Crous & M.J. Wingf.) Crous, Slippers & A.J.L. Phillips. The method, however, was unsuccessful for the detection of Diplodia seriata De Not. In addition to the above-mentioned shortcomings, the RDBH was not amenable to the detection of pathogens directly from field or environmental samples, but required preparation of DNA from pure cultures. The method, however, allows for the identification of multiple pathogens in a single assay. As DNA extraction methods are amended, improved and honed to obtain DNA from environmental samples, so would it increase the usefulness of RDBH. / AFRIKAANSE OPSOMMING: Wingerd stamsiektes word veroorsaak deur patogene wat die vermoë het om wingerdplante te infekteer en dan stadige agteruitgang van dié wingerde te veroorsaak. Veral Eutypa terugsterwing het ‘n vernietigende effek op wingerde wêreldwyd deurdat dit groeikrag en oesmassa verlaag, maar ook omdat dit uiteindelik wingerdstokke kan dood. Die veroorsakende organisme is aanvanklik as Eutypa armeniacae Hansf. & Carter beskryf, die patogeen wat terugsterf by appelkose veroorsaak, maar sedert 1987 word hierdie spesies beskou as ‘n sinoniem van Eutypa lata (Pers.:Fr.) Tul & C. Tul (anamorph Libertella blepharis A. L. Smith). Dit is egter onlangs voorgestel dat ten minste twee spesies die vermoë het om wingerd te infekteer om Eutypa terugsterwing te veroorsaak. Gevolglik is molekulêre identifikasie- en karakteriseringstudies geloods om te bepaal watter spesies Eutypa terugsterwing in Suid-Afrikaanse wingerde veroorsaak. Dit het die molekulêre analise van drie molekulêre merkers behels, naamlik die interne getranskribeerde spasiëerderarea (“ITS”), die groot ribosomale subeenheid (“LSU rDNA”) en β-tubilien geen. Resultate van die filogenetiese analise dui daarop dat ’n tweede spesies, naamlik Eutypa leptoplaca (Mont.) Rappaz, saam met E. lata in geïnfekteerde plante voorkom. Saam met bogenoemde twee spesies het daar ook verwante spesies van die Diatrypaceae familie voorgekom, naamlik Cryptovalsa ampelina (Nitschke) Fuckel en Eutypella vitis (Schwein.) Ellis & Everhart. Patogenisiteitstudies wat uitgevoer is met verteenwoordigende isolate van C. ampelina, E. lata, E. leptoplaca, en E. vitis dui daarop dat almal patogene van wingerd is. Verskeie Botryosphaeriaceae spesies wat gereeld in houtagtige wingerdweefsel aangetref word, is ook patogene van wingerd. Interne simptome wat algemeen met Botryosphaeriaceae infeksies geassosieer word, kan baie maklik met dié van Eutypa terugsterwing verwar word en dit het die nood laat ontstaan om ‘n opsporingsmetode te ontwikkel wat akkuraat genoeg is om tussen veelvoudige infeksies te onderskei. ’n Omgekeerde-stippelklad-hibridisasie (OSH) metode is gevolglik aangewend om Eutypa spesies betrokke in die Eutypa-siektekompleks op ‘n vinnige, akkurate en betroubare manier op te spoor, sowel as die Botryosphaeriaceae species wat bekend is as patogene van wingerd. Die metode behels ’n saamgestelde PKR vir die vermeerdering en merk van DNS areas wat gebruik word as patogeen spesifieke peilers. Spesies-spesifieke oligonukleotiede ontwikkel vanaf die ITS, -tubilien en LSU molekulêre data is op ‘n membraan vasgeheg en gebruik om ’n diagnostiese toets te ontwikkel vir Eutypa species. Merkers ontwikkel vanaf die ITS kon E. lata and E. leptoplaca konsekwent opspoor. Die opspoor van Eutypa spesies met merkers vanaf die -tubulien en LSU gene met OSH was onsuksesvol. Die OSH metode met merkers vanaf die verlengingsfaktor-1α kon susksesvol gebruik word om Botyrosphaeria dothidea (Moug.:Fr.) Ces. & De Not., Neofusicoccum luteum (Pennycook & Samuels) Crous, Slippers & A.J.L. Phillips, Neofusicoccum parvum (Pennycook & Samuels) Crous, Slippers, A.J.L. Phillips and Neofusicoccum ribis (Slippers, Crous & M.J. Wingf.) Crous, Slippers & A.J.L. Phillips op te spoor. Dié metode kon egter nie Diplodia seriata De Not. opspoor nie. Bykomend tot bogenoemde tekortkominge, kon die omgekeerde-stippelklad-hibridisasie metode ook nie aangepas word om patogene direk vanuit plantmateriaal op te spoor nie en word DNS afkomstig vanaf suiwer kulture benodig. Dié metode laat egter identifikasie van verskeie patogene in ‘n enkele toets toe. Soos DNS ekstraksie metodes aangepas, verbeter en verfyn word om DNS vanuit plantmateriaal te verkry, sal die bruikbaarheid van die omgekeerde stippelklad hibridisasie metode ook verbeter.