Journal article co-authored by the author inserted at end (Plant pathology (1991) 40, 67-77) / Includes bibliographical references (leaves 124-167) / xxv, 167 leaves : ill., plates ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Describes the isolation of antibody and DNA probes which vary in their reaction to different anastomosis groups of Rhizoctonia solani. Evidence is presented to show that isolates from anastomosis group 8 are biochemically distinct from isolates in other anastomosis groups found in South Australia. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Sciences, 1992

"May 2002" / Bibliography: leaves 160-171. / xi, 189 leaves : ill. (some col.), plates (some col.) ; 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 Applied and Molecular Ecology, 2002

Bibliography: leaves 218-233. / xiii, 233 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis identifies a strong relationship between Zn nutrition of medics and severity of disease by R. solani (AG8) which may be a major factor contributing to the current decline in medic pastures observed in Australia. The effect of seed nutritional value had a profound impact on the growth of medics and may also be a key factor in poor medic growth. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 1998

Thesis (Ph. D.) in Biochemistry and Molecular Biology--University of Maine, 2001. / Includes vita. Includes bibliographical references (leaves 71-83).

The chemicals inducers SA, BABA, and BTH were tested as seed treatment and soil drench on a partial-resistant cultivar of sugar beet grown in sand infested with the Rhizoctonia solani AG 2-2IIIB. In another series of experiments, BTH was applied as soil drench on sugar beet plants inoculated with R. solani. The chemical inducers were ineffective in reducing pre-emergence damping-off and post-emergence plant mortality. Despite these results, treatment with BTH altered the levels of expression ratios of four defence encoding genes associated with systemic resistance: chitinase, peroxidase, chalcone isomerase, and chalcone synthase. BTH sensitised sugar beet plants without the necessity of R. solani infection to up-regulate substantially the transcript level ratios of chalcS and chit3, while levels of chalcI were down-regulated levels below 1. Of interest, was the significant increase of transcript levels of chit3 in sugar beet plants infected with R. solani and treated with BTH. In conclusion, sugar beet plants were capable of over expressing selected genes in response to a chemical inducer, but contrary to what had been reported, gene activation in sugar beet as a result of BTH treatment does not confer disease resistance against R. solani.

Stachybotrys elegans is a mycoparasite of the soilborne plant pathogen fungus Rhizoctonia solani. The mycoparasitic activity of S. elegans is correlated with the production of cell wall-degrading enzymes such as chitinases. This study details the cloning and characterization of the cDNA, sechi44, that encodes an extracellular endochitinase. The expression regulation of sechi44 was altered when S. elegans was in interaction with its host, R. solani, and also when the mycoparasite was grown on minimal media amended with different carbon and nitrogen sources. Direct contact with R. solani significantly upregulated sechi44 expression which followed a cyclical pattern suggesting that this gene has a role not only in mycoparasitism, but also in linear growth of the mycoparasite. The addition of high concentrations of glucose and ammonium triggered a decrease of sechi44 expression suggesting that sechi44 is subject to glucose and ammonium repression. In a separate study, several genes (1016 clones) whose transcription was substantially up-regulated during the mycoparasitic interaction were identified using SSH and microarray analysis. Twenty-five percent (261 clones) of these were sequenced and assigned to putative functions. Among them, 15 expressed sequence tags (ESTs) were identified in R. solani whose functions were related to defense while the majority of ESTs were identified in S. elegans and assigned functions related to toxin metabolism, pathogenic process, stress response., multidrug resistance, apoptosis, transport, ATP synthesis, replication, transcription and DNA repair, translation, transduction, protein degradation, and ribosomal protein. The overexpression of 13 selected genes of S. elegans was validated and confirmed using quantitative reverse transcription polymerase chain reaction (QRT-PCR). The temporal gene expression of nine genes was monitored when the mycoparasite was grown on R. solani (host) and Sclerotinia sclerotiorum (non-host) mycelia and sclerotia. Some genes such as seglu, selec, and se151 were completely inhibited by the presence of non-host hyphae suggesting that these genes play an important role during mycoparasitism. Also, the absence of these corresponding transcripts suggests that the non-host produces transcription inhibitors. As expected, gene expression of cytochrome P450 was highly up-regulated early after germination of S. elegans conidia. This is in agreement with our finding in the EST data mining study, in which a role in toxin production was assigned to cytochrome P450.

The mycoparasite Stachybotrys elegans represents a potential biocontrol agent of Rhizoctonia solani, the causal organism of potato stem canker. The differential expression of two mycoparasitism-induced genes was monitored in S. elegans during interactions with its host, Rhizoctonia solani, and a non-host, Sclerotinia sclerotiorum. Using real-time reverse-transcription polymerase chain reaction (QRT-PCR), comparative analyses demonstrated that hyphal and sclerotial forms triggered different patterns of gene expression in the mycoparasite, as did the presence of the host or non-host. The calmodulin gene did not appear to be involved in conidial germination or appressoria formation of S. elegans. Potential roles of calmodulin during mycoparasitism are suggested, but further studies are required. The expression of the endochitinase-encoding gene, sechi44, was susbstantial only at later stages of interaction with living host sclerotia. Host defense mechanisms probably play a role in regulating sechi44 expression. Knowledge of the genetic mechanisms underlying this mycoparasitic relationship will further our knowledge on the potential use of S. elegans in biocontrol strategies. / Le mycoparasite Stachybotrys elegans est un agent potentiel de lutte biologiquepour le contrôle de Rhizoctonia solani, un phytopathogène causant le chancre dela tige et des stolons chez la pomme de terre (Solanum tuberosum). L'expressionde deux gènes induits pendant le mycoparasitisme a été étudiée chez S. elegans,alors que le mycoparasite était en interaction avec son hôte, R. solani, et un nonhôte,Sclerotinia sclerotiorum en utilisant la PCR quantitative en temps réel. Desanalyses comparatives ont démontré que les différentes formes d'hyphes et desc1érotes, ainsi que la présence de l'hôte ou du non-hôte, induisent différentspatrons d'expression. Le gène codant pour la calmodulin (calmodulin) ne semblepas être impliqué dans la germination des conidia ou dans la formation desappressoria chez S. elegans. Des rôles possibles de calmodulin sont suggérés,mais des études plus poussées demeurent nécessaires. L'expression du gènesechi44, codant pour une endochitinase, est importante dans des stades plusavancés du mycoparasitisme sur les sc1érotes vivants de 1 'hôte. Des mécanismesde défense de l'hôte jouent probablement un rôle important dans la régulation del'expression de sechi44. Une meilleure connaissance de la régulation génétiquelors du mycoparasitisme pourrait nous aider à évaluer le potentiel de S. elegansdans des stratégies de biocontrôle.

Thesis (Ph. D.)--University of Adelaide, Dept. of Plant Science, 1994. / Includes bibliographical references (leaves 149-173).

Thesis (Ph. D.)--University of Adelaide, Dept. of Plant Science, 1998. / Includes bibliographical references (leaves 218-233).

Made available in DSpace on 2014-06-11T19:28:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2002-03Bitstream added on 2014-06-13T19:16:47Z : No. of bitstreams: 1 tofoli_jg_me_botfca.pdf: 325404 bytes, checksum: 21b23979c734273014381947d0594a68 (MD5) / O presente trabalho visou verificar a ação “in vitro” e “in vivo” de alguns fungicidas e do indutor de resistência acibenzolar-S-methyl (BTH) no controle da pinta preta do tomateiro e seus reflexos na produção. A ação “in vitro” de fungicidas, nas concentrações de 0, 1, 10 e 100 μgmL-1 do ingrediente ativo, foi verificada com base no crescimento micelial, germinação de conídios e efeito anti-esporulante sobre A. solani. Em condições de casa de vegetação foram estudadas as ações: preventiva, residual e curativa de fungicidas em cultivares com diferentes níveis de resistência a pinta preta. Em experimentos de campo, realizados nos municípios paulistas de Sumaré (1999), Socorro (2000) e Bragança Paulista (2000 e 2001), foi avaliada a ação de diferentes grupos fungicidas e acibenzolar-S-methyl (isolado, em mistura com fungicidas e em programas de aplicação) sobre: a severidade da doença (folíolos e hastes); redução de área foliar; incidência de frutos sadios; doentes e danificados pelo sol; massa fresca de frutos sadios, produção em kilos por 10 plantas e porcentagem de frutos grandes, médios e pequenos (Bragança Paulista, 2001). Todos os fungicidas apresentaram ação positiva e diferenciada para todos os parâmetros avaliados, em função das características inerentes de cada princípio ativo. Os maiores potenciais de controle foram verificados para os fungicidas com maior especificidade e ação sistêmica... . / The aim of this study was to verify the “in-vitro” and in-vivo effectiveness of various fungicides and plant activator acibenzolar-S-methyl (BTH) in the control of tomato early blight and its effects on yield. The in-vitro effect of the fungicides, in the concentrations 0, 1, 10 and 100 μgmL-1 of the active ingredient, was assessed based on mycelial growth, conidial germination, and the antisporulating effect on A. solani. The various groups of fungicides were studied to compare their preventative, residual and curative efficacy, in greenhouse environment. Field tests were conducted in the state of São Paulo, Brazil, in the countries of Sumaré (1999), Socorro (2000) and Bragança Paulista (2000 and 2001), to compare the effect of various fungicide groups and acibenzolar-S-methyl (alone, mixed with the fungicides, or applied in conjunction with fungicidal treatments) on various parameters: the severity of the disease (leaflets and stems); percentage of leaf drop; relative numbers of healthy fruit as compared to diseased or sun-damaged fruit; yield in kg per 10 plants; and the relative percentages of large, medium and small-sized fruits (Bragança Paulista, 2001). All the fungicides presented a positive effect on all of the parameters evaluated, consistent with the active ingredients of each. The greatest efficacies of control were shown by systemic, more-specific fungicides. In regard to mycelial growth and conidial germination, the greatest inhibition percentages were obtained with metconazole, tebuconazole, difenoconazole, iprodione, cyprodinil, procymidone, prochloraz, fluazinam and pyrimethanil. The fungicides kresoxim methyl, azoxystrobin, pyraclostrobin+methiram, fenamidone+chlorothalonil and famoxadone+mancozeb presented an intermediate degree of inhibition on the mycelial growth and complete inhibition of conidial germination at concentrations of 1 μgmL-1 and above... (Complete abstract, click electronic address below).