Thesis (Ph. D.)--University of Wisconsin--Madison, 1984. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographies.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 91-101).

Th. 3e cycle--Prod. et trait. des matières prem. vég.--Toulouse--I.N.P., 1984. N°: 205.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2015-04-23T11:22:49Z No. of bitstreams: 2 Dissertação - Jacqueline Campos Borba de Carvalho - 2013.pdf: 2453380 bytes, checksum: 04cd0ef2d26879895e9dfc3e3f757f13 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-04-23T11:34:04Z (GMT) No. of bitstreams: 2 Dissertação - Jacqueline Campos Borba de Carvalho - 2013.pdf: 2453380 bytes, checksum: 04cd0ef2d26879895e9dfc3e3f757f13 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-04-23T11:34:04Z (GMT). No. of bitstreams: 2 Dissertação - Jacqueline Campos Borba de Carvalho - 2013.pdf: 2453380 bytes, checksum: 04cd0ef2d26879895e9dfc3e3f757f13 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2013-03-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Rice blast caused by the fungus Magnaporthe oryzae B. Couch [anamorfo - Pyricularia oryzae Cav.] occurs in all rice growing regions of the world. The sustainable agriculture requires the introduction of biological control as one of the components in the integrated disease management. The microorganisms associated to plants are capable of producing secondary metabolites such as alkaloids which may have a role in biological control. The objective of the present study consists, isolation and identification of secondary metabolites of the micorrhizal fungus Rhizoctonia sp. obtained from Epidendrum nocturnum and evaluate in vitro and in vivo antagonism to M. oryzae. Ten fungal isolates were used to test the antibiosis against M. oryzae. The isolate En07 of Rhizoctonia sp. exhibited a greater halo of inhibition and consequently was considered the best in vitro antagonist to M. oryzae. Crude, mycelial and lyophilized extracts of micorrhizal isolate were obtained. The analysis by CCD of these three extracts showed positive results in relation to Dragendorff, indicating the presence of phenolics. The analysis of RMN 1H and masses showed the presence of aromatic hydrogens and phenolics. Five concentrations of each extract were prepared and utilized in the studies on in vitro mycelial inhibition of M. oryzae and observed 77.86% of pathogen reduction by crude extract (700 μg/mL). Two crude extract treatments (520 μg/ml and 120 μg/ml) significantly reduced the radial growth of the pathogen compared to control. The crude extract showed best results for mycelia inhibition of the pathogen, followed by lyophilized and mycelial extracts. In two trials, the crude extract at 0.52 μg.μL-1 also reduced the formation of appressoria of M. oryzae by 100%. Two greenhouse experiments were conducted on leaf blast suppression with the cultivar Primavera, using completely randomized design with three replications. In both these trials, the mycelial extract (1860 μg/ml and M.o 3x105) showed marked reduction of leaf blast severity in relation to control by 59.27% and 77.58% respectively. In the second trial, the second treatment (1040 μg/mL and M.o3x105) of crude extract reduced AUDPC by 64.63% compared to control. The results showed that the metabolites of Rhizoctonia sp. posses great potential for biological control of rice blast. / A brusone ocorre em todas as áreas produtoras de arroz do mundo, e é causada pelo fungo Magnaporthe oryzae B. Couch [anamorfo - Pyricularia oryzae Cav.]. Seu controle, realizado pelo manejo que integra resistência genética, práticas culturais e controle químico, requer a inserção de agentes biológicos, além de assegurar uma agricultura mais sustentável. Os microrganismos associados às plantas são capazes de produzir metabólitos secundários como os alcaloides que podem atuar no controle biológico. O presente trabalho objetivou isolar os metabólitos secundários do fungo micorrízico Rhizoctonia sp. obtido de Epidendrum nocturnum, e avaliar o antagonismo in vitro e in vivo com M. oryzae. Todos os ensaios foram conduzidos em delineamento inteiramente casualizado. Um ensaio de antagonismo foi avaliado, pareando-se, 10 isolados fúngicos e M. oryzae, e identificou-se que o isolado En07 foi o que apresentou o maior halo de inibição e consequentemente o melhor antagonismo in vitro sobre M. oryzae. Foram obtidos três extratos do isolado micorrízico (bruto, micelial e liofilizado) que foram analisados por quatro métodos diferentes e complementares. A análise por Cromatografia em Camada Delgada dos três extratos mostrou-se positiva frente ao reativo de Dragendorf, sugerindo a presença de compostos fenólicos. Na análise dos espectros de Ressonância Magnética Nuclear e de massas verificou-se a presença de hidrogênios aromáticos e de compostos fenólicos. Cinco concentrações de cada extrato foram preparadas e utilizadas nos ensaios de inibição micelial de M. oryzae in vitro e observou-se 77,86% de redução do patógeno pelo extrato bruto (700 μg/mL). Dois tratamentos do extrato bruto (520 μg/ml e 120 μg/ml) reduziram o crescimento radial do patógeno de forma significativa quando comparado com a testemunha. Verificou-se que o extrato bruto apresentou os melhores resultados para a inibição micelial do patógeno, seguido dos extratos liofilizado e do micélio. Em dois ensaios o extrato bruto a 0,52 μg.μL-1 também reduziu o número de apressórios formados de M. oryzae em 100%. Foram conduzidos dois ensaios de supressão de brusone foliar em arroz, in vivo, com a cultivar Primavera em três repetições. Nos dois ensaios destacou-se o extrato micelial (1860 μg/ml e M.o 3x105) que proporcionou maiores reduções da severidade de brusone nas folhas em relação ao controle com 59,27% e 64,63%, respectivamente. No segundo ensaio o tratamento 2 (1040 μg/mL e M.o3x105) do extrato bruto reduziu a AACPD em 24,93% em relação à testemunha. Os resultados mostraram que o metabólito de Rhizoctonia sp. possui grande potencial para o controle biológico da brusone.

This study addressed the possibility of rice blast fungus (Magnaporthe grisea) as a potential bioherbicide for the control of crabgrass (Digitaria sanguinalis), in turf/lawn plantings. Experiments were: (i) evaluation of the effect of bioherbicide inoculum dosage (titer) on disease severity in crabgrass; (ii) competition between crabgrass and tall fescue (Festuca arundinacea Schreb. 'Fawn') and the additive effect of rice blast bioherbicide on the competitiveness of crabgrass; (iii) survival of rice blast spores under non-conducive infection conditions on crabgrass; and (iv) effect of multiple inoculations of rice blast fungus and subsequent disease on crabgrass.Spore concentrations of 5 x 105 to 1 x 106 conidia/mI had no significant difference in effect on mean biomass reduction of treated crabgrass. All produced tissue death and loss of vigor in treated crabgrass, but no plant death. In one trial, a spore concentration of 2 x 106 conidia/ml produced 100% biomass loss in treated crabgrass.Competition studies indicated crabgrass will out-compete fescue 'Fawn' in plots of equal numbers of each plant, i.e., 3 fescue and 3 crabgrass. In 10 x 10 cm mini-lawns of fescue interspersed with 5 crabgrass plants, fescue will out-compete the crabgrass. In mini-lawns of fescue and crabgrass, infection of crabgrass with non-lethal doses of rice blast fungus improved fescue's ability to out-compete crabgrass. Three methods of investigating competition were tested. Mini-lawns sown with 0.5 g fescue seed (approx. 200 seeds) with crabgrass seed sown into centers of the four quadrants and in center of the mini-lawn, worked best.Survival of Magnaporthe grisea conidia under non-conducive conditions was tested by drying inoculated crabgrass seedlings for 0-48 hours prior to dew-deposition. Treatments verified spores remain viable at least 24 hours on crabgrass leaves under greenhouse conditions (25-40° C and 25-75% relative humidity).Two successive inoculations (at 3 days and 7 days after primary inoculation) of crabgrass with M. grisea conidia (5 x 105 conidia/ml) resulted in significant reduction in growth compared to a single spore application.Results suggested Magnaporthe grisea exhibits potential for future development as a commercial bioherbicide to control crabgrass (Digitaria sanquinalis). Current studies investigated integration in lawn grass, but should be applicable to situations anywhere crabgrass is considered a weed e.g., in corn (Zea mans) or soybeans (Glycine max). / Department of Biology

Thesis (Ph. D.)--Ohio State University, 2005. / Available online via OhioLINK's ETD Center; full text release delayed at author's request until 2006 June 1.

The filamentous fungus Magnaporthe oryzae is a devastating pathogen of cultivated rice. M. oryzae elaborates a pressurized dome-shaped infection structure, called the appressorium, which physically ruptures the cuticle and gains entry into host tissue. Intracellular invasive hyphae invade neighbouring host cells through plasmodesmata. The Pmk1 MAPK cascade is well known for its roles in regulating the formation and function of the appressorium. Interestingly, ∆pmk1 mutants cannot infect host plant tissue through wounds, suggesting a role in invasive growth. Here, I define biological functions of the Pmk1 MAPK at various stages of the life cycle, by using a controllable version of Pmk1 that is specifically inhibited by a cell-permeable compound without disturbing other wild-type kinases. The Pmk1 MAPK signalling regulates morphogenesis of narrow invasive hyphae traversing the host cell wall, and modulates production of several putative secreted effectors, providing a direct link between the signalling cascade and effector-driven host immune suppression. These results indicate that the Pmk1 pathway is a central regulator of infection-related development necessary for many stages of plant infection including appressorium development, plant penetration, and importantly tissue colonisation. I also report the role of cell cycle progression in the development of plant infection structure. By using two novel conditional mutants that arrest in S and G2 phases, I defined that S-phase progression is crucial for appressorium-mediated plant penetration.

Orientador: Paulo Cezar Ceresini / Resumo: Na primeira parte de nosso estudo descrevemos a associação de Pyricularia pennisetigena e P. zingibericola a gramíneas invasoras de áreas de trigo no centro-sul do Brasil. Desconhece-se, entretanto, qual o potencial de P. pennisetigena e P. zingibericola como patógenos de poáceas de interesse econômico para a agricultura brasileira. Dessa forma, objetivamos caracterizar o espectro de patogenicidade de P. pennisetigena e P. zingibericola a braquiária, cevada e trigo e compará-lo com aP. grisea e com a espécie até até recentemente descrita como P. oryzae patotipo Triticum, de ocorrência generalizada no agroecossistema brasileiro. Foram testados 20 isolados de Pyricularia spp. obtidos de amostras de folhas infectadas de plantas invasoras de campos de trigo. A classificação dos isolados em espécies distintas de Pyricularia foi efetuada usando-se filogenia molecular baseada nas sequencias parciais dos genes actina e calmodulina. Pyricularia pennisetigena e P. zingibericola inoculadas em folhas, foram patogênicas a braquiária, cevada e trigo, com diferenças na agressividade entre as espécies. Pyricularia zingibericola foi a espécie mais agressiva a braquiária e cevada, enquanto P. pennisetigena foi a espécie mais agressiva em plantas jovens de trigo. Por outro lado, P. grisea isolada de Digitaria sanguinalis ou de Urochloa spp. não infectou trigo. A análise filogenética das regiões ACT e CAL concatenadas reproduziu as relações filogenéticas e a magnitude das diferenças descritas e... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In the first part of our study we described the association Pyricularia pennisetigena and P. zingibericola associated with invasive grasses from wheat cropping areas in South-Central Brazil. Howeever, the potential of P. pennisetigena and P.zingibericola as pathogens to poaceous plants of economic interest for Brazilian agriculture is still unknown. Thereforne, this study aimed to characterize the pathogenicity spectrum of P. pennisetigena and P. zingibericola to signal grass, barley and wheat and compare with P. grisea and with the species until recently described as P. oryzae pathotype Triticum, of widespread occurrence in the Brazilian agro-ecosystem. Twenty isolates of Pyricularia spp. obtained from samples of infected leaves of weed species in wheat fields were tested. Classification of isolates into different species of Pyricularia was performed using molecular phylogeny based on the partial actin and calmodulin gene sequences. Pyricularia pennisetigena and P. zingibericola inoculated on leaves were pathogenic to signal grass, barley and wheat, with differences in aggressiveness between species. Pyricularia zingibericola was the most aggressive species to signal grass and barley, while P. pennisetigena was the most aggressive species to young plants of wheat. On the other hand, P. grisea isolated from Digitaria sanguinalis or Urochloa spp. did not infect wheat. Phylogenetic analysis of the concatenated regions ACT and CAL reproduced the phylogenetic relationships and ... (Complete abstract click electronic access below) / Doutor

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2015-10-27T14:25:17Z No. of bitstreams: 2 Dissertação - Amanda Abdallah Chaibub - 2014.pdf: 1263990 bytes, checksum: 48328d656f5321ae2882086283462be4 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-10-29T10:11:31Z (GMT) No. of bitstreams: 2 Dissertação - Amanda Abdallah Chaibub - 2014.pdf: 1263990 bytes, checksum: 48328d656f5321ae2882086283462be4 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-10-29T10:11:32Z (GMT). No. of bitstreams: 2 Dissertação - Amanda Abdallah Chaibub - 2014.pdf: 1263990 bytes, checksum: 48328d656f5321ae2882086283462be4 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2014-02-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Rice blast (Magnaporthe oryzae Couch, anamorph-Pyricularia oryzae Cav.) is the major disease of rice causing yield losses up to 100%, in the world. Its control, currently held by integrating genetic resistance, cultural practices and chemical control, requires the inclusion of biological agents. The objectives of this study were to evaluate the in vitro antagonism between C. cladosporioides and four different rice pathogens; to verify the ability of C. cladosporioides in suppressing leaf blast and to study the mechanisms involved during disease suppression. The bioassays were conducted in a completely randomized design with three replications. The antagonism in vitro was evaluated by pairing-up, in Petri dishes containing PDA medium, nine different isolates of C. cladosporioides with the rice pathogens Sarocladium oryzae (sheath rot), Monographella albescens (scald), Cochliobolus miyabeanus (brown stain) and M. oryzae. All C. cladosporioides isolates reduced colonies mycelia growth up to 53.84% in addition to hallo formation. Among the nine tested isolates, four were selected for in vivo studies. Under controlled greenhouse conditions, three different concentrations were tested, in two different applications way; 1) 48 hours before challenger inoculation with M. oryzae; 2) mixture of M. oryzae and C. cladosporioides conidia suspensions. The isolated C24 C. cladosporioides (5x105) sprayed 48 hours, before challenger inoculation reduced 97.1% of leaf blast severity, and the spray mixture of conidial suspensions of C24 C. cladosporioides (5x101) and M. oryzae 3x105 spray of decreased leaf blast severity by 88.6%. Subsequently, the mechanisms involved in leaf blast suppression were investigated by using the same isolate, both applications methods and by collecting rice plants leaves sprayed with C. cladosporioides and M. oryzae. The application of C. cladosporioides 48 hours before challenger inoculation with M. oryzae and the conidial suspensions of mixture of M. oryzae and C. cladosporioides reduced to 83.9% and 78.6% of leaf blast severity, respectively. It was detected that, in the presence of C. cladosporioides and absence of the pathogen activity of enzymes GLU, LIPOX, PAL and POX increased significantly. In the presence of, C. cladosporioides and M. oryzae, POX and PAL activity and AS content also significantly increased, in both application forms. Scanning electron microscopy confirmed the physical interaction between plant/biological agent/pathogen during the penetration phase. It was proved that C. cladosporioides is a biological agent efficient in activating biochemical defense mechanisms of the rice plant during leaf blast suppression. / A brusone (Magnaporthe oryzae Couch, anamorfo - Pyricularia oryzae Cav.) é a principal doença do arroz no mundo causando perdas na produtividade de até 100%. Seu controle, atualmente realizado pelo manejo que integra resistência genética, práticas culturais e controle químico, requer a inserção de agentesbiológicos. Os objetivos do presente trabalho foram avaliar o antagonismo in vitro entre Cladosporium cladosporioides e os patógenos do arroz; verificar a capacidade de C. cladosporioides em suprimir a brusone foliar e estudar os mecanismos envolvidos na supressão da doença. Todos os ensaios foram conduzidos em delineamento inteiramente casualizado, com três repetições. O antagonismo, in vitro, foi avaliado pareando-se, em placas de Petri contendo meio de cultura BDA, nove diferentes isolados de C. cladosporioides com os patógenos do arroz, Sarocladium oryzae (Podridão da bainha), Monographella albescens (Escaldadura), Cochliobolus miyabeanus (Mancha parda) e M. oryzae. Todos os isolados de C. cladosporioides reduziram, em até 53,84% o crescimento micelial das colônias além de apresentarem halo; entre os nove, quatro foram selecionados para os estudos in vivo. Em condições controladas de casa de vegetação, foram testadas, em três diferentes concentrações, a aplicação antecipada, 48 horas antes da inoculação desafiadora com M. oryzae, e a aplicação da mistura das suspensões de conídios de M. oryzae e C. cladosporioides. A pulverização antecipadado isolado C24 de C. cladosporioides (5x105) promoveu 97,1% de redução da severidade de brusone foliar e a pulverização da mistura das suspensões do isolado C24 de C. cladosporioides (5x101) e M. oryzae (3x105) reduziu em 88,6%. Posteriormente, os mecanismos envolvidos na supressão da brusone foliar foram investigados com o mesmo isolado e os dois métodos de aplicação com coletas de plantas, realizadas antes e após o desafio com M. oryzae. As aplicações, antecipada e em mistura, reduziram em 83,9% e 78,6% a severidade da brusone foliar, respectivamente. Observou-se que, na ausência do patógeno a atividade de GLU, LIPOX, PAL e POX aumentaram significativamente. Na presença de M. oryzae, a atividade de POX e PAL e o teor do AS aumentaram destacadamente, em ambas as formas de aplicação. Por microscopia eletrônica de varredura confirmou-se a interaçãofísica entre planta/agente biológico/patógeno, durante a fase de penetração. C. cladosporioidesrevelou-se um agente biológico capaz de suprimira brusone foliar ativando os mecanismos bioquímicos de defesa da planta de arroz.

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