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Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 70-78). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2005. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Submitted by Reginaldo Soares de Freitas (reginaldo.freitas@ufv.br) on 2017-06-20T17:30:34Z No. of bitstreams: 1 texto completo.pdf: 1425926 bytes, checksum: ee624a74ef4a36d197d9316ae8fe4072 (MD5) / Made available in DSpace on 2017-06-20T17:30:34Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1425926 bytes, checksum: ee624a74ef4a36d197d9316ae8fe4072 (MD5) Previous issue date: 2016-08-25 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Oídio do eucalipto é uma importante doença que ocorre principalmente em casas de vegetação e minijardins clonais protegidos de eucalipto (Eucalyptus spp.) no Brasil. O fungo infecta folhas jovens e brotações. Sobre o tecido afetado, observam-se colônias superficiais isoladas ou agrupadas do fungo de coloração branca, que podem atingir toda superfície foliar e induzir malformação dos órgãos afetados e resultar em redução do crescimento e da produção de brotos para estaquia. Devido ao aumento da incidência e importância dessa doença nos últimos anos e também à falta de pesquisas relacionadas a esse patossistema, esse estudo objetivou: i) determinar a etiologia do oídio do eucalipto por meio do sequenciamento da região ITS e 28S do rDNA e de análises morfológicas de isolados de oídio coletados em diferentes regiões geográficas do Brasil; e ii) analisar o transcriptoma do patógeno durante a infecção em Eucalyptus urophylla gerado pelo sequenciamento do transcriptoma (RNA-Seq) e montagem de novo. Baseado nos resultados de análises filogenéticas e caracterização morfológica, todos os 42 isolados coletados foram identificados como Podosphaera pannosa, também conhecido como agente etiológico do oídio das roseiras. Inoculações cruzadas com isolados de P. pannosa de roseira e eucalipto demonstraram que P. pannosa pode infectar ambas as espécies. O sequenciamento do transcriptoma de P. pannosa pela plataforma Illumina resultou em 12.107 transcritos. Entre os 10 transcritos mais abundantes, encontram-se os genes codificadores de enzimas envolvidas no estabelecimento e crescimento do fungo. A predição do secretoma do fungo resultou em 217 proteínas, das quais 14 foram consideradas como candidatas a efetores. Além disso, 242 pares de primers foram desenhados a partir das sequências do transcriptoma com potencial para amplificar regiões microssatélites (Simple Sequence Repeats - SSR) de P. pannosa. Os resultados gerados neste trabalho demonstram que apenas a espécie P. pannosa causa doença no eucalipto. Além disso, fornece informações úteis para novos avanços nos estudos sobre a doença por oferecer uma base para a melhor compreensão sobre o patossistema P. pannosa- eucalipto. / Eucalypt powdery mildew is an important disease that occurs mainly in greenhouses and protected clonal hedges of eucalypt (Eucalyptus spp.) in Brazil. The fungal pathogen infects new leaves and shoots. White superficial colonies isolated or grouped that grow over the affected plant tissue are observed, which can subsequently spread to all leaf surface, causing leaf malformation and reduction on growth and production of shoots for mini-cutting. Because this disease has increased in incidence and importance in recent years, and research on this pathosystem is largely lacking, the objectives of this study were to i) determine the etiology of the disease through ITS and 28S rDNA sequencing and morphological analyses of powdery mildew pathogens isolates collected in different regions in Brazil; and ii) analyze the transcriptome of the powdery mildew pathogen during infection on Eucalyptus urophylla generated by RNA sequencing (RNA-Seq) and de novo assembly. Based on the results of phylogenetic analyses and morphological characteristics, all 42 pathogen isolates collected were identified as Podosphaera pannosa, also known to cause rose powdery mildew. Cross inoculations with pathogen isolates from rose (Rosa spp.) and eucalypt demonstrated that P. pannosa can infect both host species. The transcriptome sequencing by Illumina platform resulted in 12,107 transcripts. Among the 10 most abundant transcripts included genes encoding enzymes involved in fungal establishment and growth. The secretome prediction resulted in 217 proteins, of which 14 were considered as candidate effectors. In addition, 242 primer pairs were designed from the transcriptome sequences with potential to amplify P. pannosa microsatellites (Simple Sequence Repeats – SSR) regions. The results demonstrate that P. pannosa is the only causal agent found for eucalypt powdery mildew. In addition, this study provides technological advances in the study of this disease that will provide a basis for a better understanding of the P. pannosa- eucalypt pathosystem.

Certains champignons sont très dommageables pour les plantes mais aussi pour la conservation après récolte des produits végétaux. Les restrictions réglementaires concernant l’utilisation des fongicides nécessitent de trouver des solutions alternatives. L'amélioration de la résistance des plantes en utilisant des méthodes physiques, comme les rayonnements UV, peut présenter une alternative prometteuse en association avec d’autres méthodes dans le cadre d’une protection intégrée des cultures. L'objectif de cette thèse a été d’étudier l’effet des rayonnements UV-C sur la sensibilité des plantes aux agents pathogènes. Les rayonnements UV-C ont été appliqués durant la culture, seuls ou en combinaison à des agents de biocontrôle, ou en post-récolte. Les expérimentations ont été menées sur deux espèces végétales : le fraisier et la tomate.Sur fraisier, des traitements UV-C à une dose de 1,70 kJ/m² entraînent une diminution systématique d'environ 20 % de la sensibilité des feuilles à Botrytis cinerea et diminuent jusqu’à 50 % le nombre de feuilles attaquées par Podosphaera aphanis, l’agent causal de l’oïdium. Chez la tomate, la protection des feuilles contre B. cinerea atteint 43 % avec une dose d’UV-C cumulée de 4,0 kJ/m². Ces mêmes traitements UV-C appliqués sur fruits réduisent la sensibilité des fraises vis-à-vis de Rhizopus de 75 % mais aucun effet n’est observé vis-à-vis de B. cinerea. Au contraire, sur fruits de tomate, la sensibilité est diminuée d'environ 63 % contre cet agent pathogène. Parallèlement, des tests biochimiques et gustatifs suggèrent que la qualité des fruits n’est pas significativement améliorée ni altérée par les expositions UV-C. Malgré un effet germicide marqué des rayonnements UV-C sur feuilles de fraisiers, aucun effet bénéfique de l’application de ces rayonnements sur le niveau d’efficacité d’agents de lutte biologique n’a été mis en évidence.Nos observations sont encourageantes pour envisager une utilisation de cette méthode dans un schéma de protection intégrée des cultures. Cependant, une compréhension claire de la façon dont les rayonnements UV-C sont perçus par les plantes et traduits en mécanismes de défense est nécessaire avant que leur utilisation ne soit recommandée sur le terrain. / Some fungi are very damaging during plant cultivation and also in post-harvest storage of products. Regulatory restrictions on fungicide use require alternative solutions. Improving plant resistance using physical methods, such as aplication of UV radiation, can be a promising alternative in association with other methods as part of an integrated pest management strategy. The objective of the present thesis was to study the effect of UV-C aplication on the sensitivity of plants to fungal pathogens. UV-C radiation was applied during plant cultivation, alone or in combination with biocontrol agents, or in post-harvest. Experiments were conducted on two plant species: strawberry and tomato.On strawberry plants, UV-C treatments at 1.70 kJ/m² result in a systematic 20 % decrease in leaves sensitivity to Botrytis cinerea and in a reduction by up to 50 % of the number of leaves infected by Podosphaera aphanis, the causal agent of powdery mildew. In tomato, leaves protection against B. cinerea reaches 43 % with a cumulative dose of 4.0 kJ/m². UV-C treatments applied on fruits reduce the strawberry sensitivity to Rhizopus by 75 % but no effect is observed against B. cinerea. On the contrary, sensitivity against B. cinerea is reduced by 63 % on tomato fruit. Biochemical and taste tests suggest that fruit quality is not significantly improved or altered by UV-C treatment. Despite a marked germicidal effect of UV-C radiation on strawberry leaves, it has no significant effect on the protective efficacy of biocontrol agents.Our observations are encouraging to consider the use of this tool in an integrated crop protection scheme. However, a clear understanding of how UV-C radiations are perceived by plants and their translation into defense mechanisms is necessary before their use is recommended in the field.

Submitted by Ricardo Cedraz Duque Moliterno (ricardo.moliterno@uefs.br) on 2015-10-13T22:42:35Z No. of bitstreams: 1 Tese_Renata Nat?lia_PPG_RGV.pdf: 4534182 bytes, checksum: 0d860c2ab1b6041788983d56cd000549 (MD5) / Made available in DSpace on 2015-10-13T22:42:35Z (GMT). No. of bitstreams: 1 Tese_Renata Nat?lia_PPG_RGV.pdf: 4534182 bytes, checksum: 0d860c2ab1b6041788983d56cd000549 (MD5) Previous issue date: 2015-07-24 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / The powdery mildew is one of the most important foliar diseases that attack the watermelon and other cucurbits in Brazil and in the world. The principal identification elements by the consumer are based on the external appearance and quality of the fruit. The objective of this study was to identify microsatellite markers linked to resistance to powdery mildew and to the stripe pattern of watermelon fruits with microsatellite markers. Plants of the parents, F1 and F2, which are the result of a cross between the cultuvars BRS Opara (powdery mildew resistant and with clearly defined stripes fruit) and P?rola (powdery mildew susceptible and with diffuse stripes fruit), were phenotyped in the field for resistance or susceptibility to powdery mildew and, after of the harvest, the fruits was morphologically characterized. For these characteristics, 116 microsatellite markers were analyzed and the linkage analysis done in JoinMap 2.0. Segregation in the F2 population demonstrated that resistance powdery mildew and the stripe pattern are controlled by a single dominant gene. The microsatellite loci MCPI_11, CYSTSIN and BVWS02441 showed linked to the powdery mildew resistance gene at 2.6 cM with LODs ?score? of 31.42 and are located in chromosome two of the watermelon genome. The microsatellite loci MCPI_05 and MCPI_16 showed a linkage to the stripe patterns of watermelon fruits at a distance of 1.5 and 1.8 cM with a LODs ?scores? of 39.28 and 38.11 respectively, and are located in the chromosome six of the watermelon genome. These markers can be used in the marker assisted selection process in watermelon improvement programs. / O o?dio ? uma das principais doen?as foliares que acomete a melancia e outras cucurbit?ceas, no Brasil e no mundo. Os principais elementos de identifica??o de uma cultivar pelo consumidor est?o relacionados com a apar?ncia externa e qualidade do fruto. O objetivo deste trabalho foi identificar marcadores microssat?lites ligados ? resist?ncia ao o?dio e ao padr?o de listras de frutos de melancia. Plantas dos parentais, de F1 e de F2, resultantes do cruzamento entre as cultivares BRS Opara (resistente ao o?dio e com padr?o de listras claramente definidas) e P?rola (suscet?vel ao o?dio e com padr?o de listras difusas) foram fenotipadas em campo para resist?ncia ou suscetibilidade ao o?dio e, ap?s a colheita, os frutos foram caracterizados quanto ao padr?o de listras. Para essas duas caracter?sticas foram analisados 116 marcadores microssat?lites e as an?lises de liga??o foram realizadas no programa JoinMap 2.0. A segrega??o da popula??o F2 demonstrou que a resist?ncia ao o?dio e o padr?o de listras de frutos de melancia s?o caracter?sticas monog?ncias e dominantes. Os microssat?lites MCPI_11, CYSTSIN e BVWS02441 mostraram-se ligados ao gene que confere resist?ncia ao o?dio a 2,6 cM com LODs ?score? de 31,42 e est?o localizados no cromossomo dois no genoma da melancia. Os microssat?lites MCPI_05 e o MCPI_16 est?o ligados ao padr?o de listras de frutos de melancia a uma dist?ncia de 1,5 e 1,8 cM com LODs ?score?de 39,28 e 38,11, respectivamente, e est?o localizados no cromossomo seis do genoma da melancia. Esses marcadores poder?o ser utilizados no processo de sele??o assistida por marcadores em programas de melhoramento de melancia.

Knowledge of disease epidemiology and the impact of plant nutrient status on development of disease is fundamental in establishing effective management strategies for crop pathogens such as Podosphaera aphanis Br. (Braun et al., 2002), the causal agent of powdery mildew on strawberries. The following study investigated the conditions conducive for powdery mildew in strawberry crops in South Australia, the effect of foliar concentration of potassium and calcium on yield and pathogen development on the strawberry cultivars Aromas (resistant to powdery mildew) and Selva (susceptible), the potential for use of foliar-applied potassium silicate to control disease and identification of genes differentially expressed during disease. Meteorological conditions associated with establishment of powdery mildew were observed over three consecutive seasons in commercial strawberry crops grown in Woodside, South Australia. Conducive conditions appear to be >28 oC, <55 % relative humidity (RH) with no rain during the day (for conidiation), followed by a night with >10 oC, >90 % RH and no rain (for germination). Colony development was then promoted by days of >15 oC and <70 % RH, with nights of >8 oC, >80 % RH and less than 2 mm rain in every 24 hour period. These are consistent with epidemiological studies of this pathogen (Peries, 1962a; Jhooty and McKeen, 1964; Mukerji, 1968; Perera and Wheeler, 1975; Byrne et al, 2000; Miller et al, 2003; Blanco et al, 2004; Davik and Honne, 2005; Amsalem et al, 2006). This knowledge may facilitate prediction of times considered high risk for establishment of powdery mildew in strawberry crops. Subsequently, this may allow optimisation of fungicide application and improved management of this disease and reduced yield loss and management expenses. P. aphanis developed at an increased rate on leaves of Selva with low calcium content compared with development on normally fertilised leaves. Increased numbers of conidia germinated successfully on leaves of Aromas with low calcium content compared with development on normally fertilised Aromas leaves, however, the germinated conidia still failed to develop into sporulating colonies. Potassium nutrition had no obvious effect on P. aphanis development. Foliar concentration found to be adequate for growth of cultivars, Selva and Aromas were 6.0 mg/g and 4.5 mg/g Calcium, dry weight and 11.0 mg/g and 12.5 mg/g potassium, dry weight (respectively). Potassium silicate, buffered to pH 7.0 and applied as a foliar fertiliser, reduced the severity of powdery mildew below the economic threshold, though not below the disease severity on plants treated with the fungicide, Systhane® (Bayer CropScience). As potassium silicate can be produced organically this compound may provide a useful management tool for both organic and conventional strawberry growers. Although the cultivar Aromas was not immune to disease under conducive conditions and high inoculum load in the field, inoculation of healthy Aromas plants with P. aphanis in the laboratory failed to produce disease. Conidia were seldom found attached to the leaf surface of healthy Aromas leaves. Germination and subsequent colony development were also not observed in inoculated samples. This suggests there is some mechanism of Aromas that inhibits development of this fungus. Preliminary investigation of differential expression in Aromas inoculated with P. aphanis, identified sequences with homology to a putative antimicrobial protein and photosynthesis-related genes. The results of these studies should enable growers to increase both crop yields and control of powdery mildew, one of the major economic diseases in South Australia. The epidemiological knowledge attained will be valuable, and may provide the basis for future forecast modelling for P. aphanis in strawberry crops in South Australia. Recommendations for calcium and potassium leaf content will allow growers to monitor their fertiliser regime for increased yield of these cultivars. Aromas was identified as a powdery mildew resistant cultivar potentially suitable for production in South Australia, and the genes associated with this resistance response may be used in studies of Fragaria species and breeding for powdery mildew resistant cultivars. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1297684 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2007

Knowledge of disease epidemiology and the impact of plant nutrient status on development of disease is fundamental in establishing effective management strategies for crop pathogens such as Podosphaera aphanis Br. (Braun et al., 2002), the causal agent of powdery mildew on strawberries. The following study investigated the conditions conducive for powdery mildew in strawberry crops in South Australia, the effect of foliar concentration of potassium and calcium on yield and pathogen development on the strawberry cultivars Aromas (resistant to powdery mildew) and Selva (susceptible), the potential for use of foliar-applied potassium silicate to control disease and identification of genes differentially expressed during disease. Meteorological conditions associated with establishment of powdery mildew were observed over three consecutive seasons in commercial strawberry crops grown in Woodside, South Australia. Conducive conditions appear to be >28 oC, <55 % relative humidity (RH) with no rain during the day (for conidiation), followed by a night with >10 oC, >90 % RH and no rain (for germination). Colony development was then promoted by days of >15 oC and <70 % RH, with nights of >8 oC, >80 % RH and less than 2 mm rain in every 24 hour period. These are consistent with epidemiological studies of this pathogen (Peries, 1962a; Jhooty and McKeen, 1964; Mukerji, 1968; Perera and Wheeler, 1975; Byrne et al, 2000; Miller et al, 2003; Blanco et al, 2004; Davik and Honne, 2005; Amsalem et al, 2006). This knowledge may facilitate prediction of times considered high risk for establishment of powdery mildew in strawberry crops. Subsequently, this may allow optimisation of fungicide application and improved management of this disease and reduced yield loss and management expenses. P. aphanis developed at an increased rate on leaves of Selva with low calcium content compared with development on normally fertilised leaves. Increased numbers of conidia germinated successfully on leaves of Aromas with low calcium content compared with development on normally fertilised Aromas leaves, however, the germinated conidia still failed to develop into sporulating colonies. Potassium nutrition had no obvious effect on P. aphanis development. Foliar concentration found to be adequate for growth of cultivars, Selva and Aromas were 6.0 mg/g and 4.5 mg/g Calcium, dry weight and 11.0 mg/g and 12.5 mg/g potassium, dry weight (respectively). Potassium silicate, buffered to pH 7.0 and applied as a foliar fertiliser, reduced the severity of powdery mildew below the economic threshold, though not below the disease severity on plants treated with the fungicide, Systhane® (Bayer CropScience). As potassium silicate can be produced organically this compound may provide a useful management tool for both organic and conventional strawberry growers. Although the cultivar Aromas was not immune to disease under conducive conditions and high inoculum load in the field, inoculation of healthy Aromas plants with P. aphanis in the laboratory failed to produce disease. Conidia were seldom found attached to the leaf surface of healthy Aromas leaves. Germination and subsequent colony development were also not observed in inoculated samples. This suggests there is some mechanism of Aromas that inhibits development of this fungus. Preliminary investigation of differential expression in Aromas inoculated with P. aphanis, identified sequences with homology to a putative antimicrobial protein and photosynthesis-related genes. The results of these studies should enable growers to increase both crop yields and control of powdery mildew, one of the major economic diseases in South Australia. The epidemiological knowledge attained will be valuable, and may provide the basis for future forecast modelling for P. aphanis in strawberry crops in South Australia. Recommendations for calcium and potassium leaf content will allow growers to monitor their fertiliser regime for increased yield of these cultivars. Aromas was identified as a powdery mildew resistant cultivar potentially suitable for production in South Australia, and the genes associated with this resistance response may be used in studies of Fragaria species and breeding for powdery mildew resistant cultivars. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1297684 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2007

Knowledge of disease epidemiology and the impact of plant nutrient status on development of disease is fundamental in establishing effective management strategies for crop pathogens such as Podosphaera aphanis Br. (Braun et al., 2002), the causal agent of powdery mildew on strawberries. The following study investigated the conditions conducive for powdery mildew in strawberry crops in South Australia, the effect of foliar concentration of potassium and calcium on yield and pathogen development on the strawberry cultivars Aromas (resistant to powdery mildew) and Selva (susceptible), the potential for use of foliar-applied potassium silicate to control disease and identification of genes differentially expressed during disease. Meteorological conditions associated with establishment of powdery mildew were observed over three consecutive seasons in commercial strawberry crops grown in Woodside, South Australia. Conducive conditions appear to be >28 oC, <55 % relative humidity (RH) with no rain during the day (for conidiation), followed by a night with >10 oC, >90 % RH and no rain (for germination). Colony development was then promoted by days of >15 oC and <70 % RH, with nights of >8 oC, >80 % RH and less than 2 mm rain in every 24 hour period. These are consistent with epidemiological studies of this pathogen (Peries, 1962a; Jhooty and McKeen, 1964; Mukerji, 1968; Perera and Wheeler, 1975; Byrne et al, 2000; Miller et al, 2003; Blanco et al, 2004; Davik and Honne, 2005; Amsalem et al, 2006). This knowledge may facilitate prediction of times considered high risk for establishment of powdery mildew in strawberry crops. Subsequently, this may allow optimisation of fungicide application and improved management of this disease and reduced yield loss and management expenses. P. aphanis developed at an increased rate on leaves of Selva with low calcium content compared with development on normally fertilised leaves. Increased numbers of conidia germinated successfully on leaves of Aromas with low calcium content compared with development on normally fertilised Aromas leaves, however, the germinated conidia still failed to develop into sporulating colonies. Potassium nutrition had no obvious effect on P. aphanis development. Foliar concentration found to be adequate for growth of cultivars, Selva and Aromas were 6.0 mg/g and 4.5 mg/g Calcium, dry weight and 11.0 mg/g and 12.5 mg/g potassium, dry weight (respectively). Potassium silicate, buffered to pH 7.0 and applied as a foliar fertiliser, reduced the severity of powdery mildew below the economic threshold, though not below the disease severity on plants treated with the fungicide, Systhane® (Bayer CropScience). As potassium silicate can be produced organically this compound may provide a useful management tool for both organic and conventional strawberry growers. Although the cultivar Aromas was not immune to disease under conducive conditions and high inoculum load in the field, inoculation of healthy Aromas plants with P. aphanis in the laboratory failed to produce disease. Conidia were seldom found attached to the leaf surface of healthy Aromas leaves. Germination and subsequent colony development were also not observed in inoculated samples. This suggests there is some mechanism of Aromas that inhibits development of this fungus. Preliminary investigation of differential expression in Aromas inoculated with P. aphanis, identified sequences with homology to a putative antimicrobial protein and photosynthesis-related genes. The results of these studies should enable growers to increase both crop yields and control of powdery mildew, one of the major economic diseases in South Australia. The epidemiological knowledge attained will be valuable, and may provide the basis for future forecast modelling for P. aphanis in strawberry crops in South Australia. Recommendations for calcium and potassium leaf content will allow growers to monitor their fertiliser regime for increased yield of these cultivars. Aromas was identified as a powdery mildew resistant cultivar potentially suitable for production in South Australia, and the genes associated with this resistance response may be used in studies of Fragaria species and breeding for powdery mildew resistant cultivars. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1297684 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2007