Thesis (MSc)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: This thesis consists of four chapters that present research findings on Colletotrichum diseases associated with Proteaceae worldwide. The first chapter is a review of literature regarding the taxonomy and histology of Colletotrichum species associated with Proteaceae. The literature is not restricted to Proteaceae hosts, as information regarding Colletotrichum on Proteaceae is very limited. In chapter two, Colletotrichum spp. associated with proteaceous hosts growing in various parts of the world were identified based on morphology, sequence data of the internal transcribed spacer region (ITS-I, ITS-2), the 5.8S gene, and partial sequences of the B-tubulin gene. Four species of Colletotrichum were associated with Proteaceae. Colletotrichum gloeosporioides was isolated from Protea cynaroides cultivated in South Africa and Zimbabwe and from a Leucospermum sp. in Portugal, but is known to occur worldwide on numerous hosts. A recently described species, C. boninense, was associated with Zimbabwean and Australian Proteaceae, but also occurred on a Eucalyptus sp. in South Africa. This represents a major geographical and host extension for the species, and a description of the African strains is provided. Colletotrichum crassipes was represented by a single isolate obtained from a Dryandra plant in Madeira. Colletotrichum acutatum was isolated from Protea and Leucadendron in South Africa as well as from other proteaceous hosts occurring elsewhere. Colletotrichum acutatum f. sp. hakea was isolated from Hakea in South Africa. In chapter three, pathogenicity of these Colletotrichum species to certain proteas was established, relative aggressiveness of the different species tested and host response to them were compared as well as the effect that wounding had on host response. From the results obtained it is concluded that C. acutatum and C. gloeosporioides are the primary pathogens associated with Colletotrichum leaf necrosis, and C. acutatum is the main cause of anthracnose and stem necrosis of Proteaceae in South Africa. A histological study was performed in chapter four in response to the findings from the previous chapter. The behaviour of two C. acutatum isolates (one originating from Protea and the other from Hakea, C. acuataum f.sp. hakea) was studied on inoculated Protea leaf surfaces using light and scanning electron microscopy. Colletotrichum acutatum from Protea formed melanised appressoria on the leaf surface, whereas C. acutatum from Hakea formed very low numbers of both melanised and unmelanised appressoria. Most of the appressoria formed by C. acutatum from Protea were formed on the cell junctions and on the periclinal walls of the epidermal cells. From this study it is clear that C. acutatum f. sp. hakea is not a pathogen of Protea. Consequently the current use of this isolate as a biological control agent of Hakea in South Africa poses no threat to indigenous Protea species. Colletotrichum acutatum from Protea (although closely related to C. acutatum f. sp. hakea), is a pathogen of Protea, which was confirmed by histological observations. In conclusion, the present study has shown that several species of Colletotrichum are associated with diseased Proteaceae. These species differed in their pathogenicity and aggressiveness when inoculated onto certain protea cultivars. These differences could be partially explained by examining the behaviour of C. acutatum on the leaf surface. It is clear, however, that the distribution of the different species, their aggressrveness on different Proteaceae and their modes of infection needs to be investigated further. This work provides a basis for future research on the long-term effective management of these pathogens in fynbos production. / AFRIKAANSE OPSOMMING: Hierdie tesis bestaan uit vier hoofstukke wat handeloor navorsing van Colletotrichum siektes van Proteaceae wêreldwyd. Die eerste hoofstuk is 'n oorsig van literatuur rakende die taksonomie en histologie van die Colletotrichum spesies wat met Proteaceae geassosieer word. Die literatuur oorsig is nie beperk tot die Proteaceae nie aangesien baie min inligting rakende Colletotrichum op Proteaceae bestaan. In die tweede hoofstuk word die Colletotrichum spesies wat met proteas in verskeie dele van die wêreld geassosieer word, op grond van morfologie, DNS volgorde data van die interne getranskribeerde spasieerder area ("ITS-I, ITS-2"), die 5.8S geen, en gedeeltelike DNS volgordes van die B-tubulin geen geïdentifiseer. Vier Colletotrichum spesies is met die Proteaceae geassosieer. Colletotrichum gloeosporioides is geïsoleer vanaf Protea cynaroides wat in Suid-Afrika en Zimbabwe gekweek is en vanaf 'n Leucospermum sp. in Portugal, maar is bekend op verskeie gashere wêreldwyd. 'n Spesie wat onlangs beskryf is, C. boninense, is met Zimbabwiese en Australiaanse Proteaceae geassosieer, maar kom ook op 'n Eucalyptus sp. in Suid-Afrika voor. Dit is 'n groot uitbreiding van die geografiese voorkoms en gasheerreeks van hierdie spesie en 'n beskrywing van die Afrikaanse rasse word gegee. Colletotrichum crassipes is verteenwoordig deur 'n enkele isolaat wat vanaf 'n Dryandra plant in Madeira verkry is. Colletotrichum acutatum is vanaf Protea en Leucadendron in Suid-Afrika asook vanaf ander proteas wat elders voorkom, geïsoleer. Colletotrichum acutatum f. sp. hakea is vanaf Hakea in Suid-Afrika geïsoleer. In hoofstuk drie is die patogenisiteit van hierdie Colletotrichum spesies teenoor sekere proteas getoets, die relatiewe aggressiwiteit van die verskillende spesies is vergelyk, asook die gasheer se reaksie teenoor die spesies en die effek wat verwonding op die gasheer gehad het. Daar kan afgelei word vanaf die resultate dat C. acutatum en C. gloeosporioides die primêre patogene is wat met Colletotrichum blaarnekrose geassosieer word, en dat C. acutatum die hoof oorsaak is van antraknose en lootnekrose van Proteaceae in Suid-Afrika. 'n Histologiese studie is in hoofstuk vier uitgevoer in reaksie op die bevindings van die vorige hoofstuk. Die gedrag van twee C. acutatum isolate (een vanaf Protea en die ander vanaf Hakea, C. acutatum f.sp. hakea) op die oppervlaktes van geïnokuleerde Protea blare is bestudeer deur gebruik te maak van lig- en skandeer-elektronmikroskopie. Colletotrichum acutatum vanaf Protea vorm gemelaniseerde appressoria op die blaaroppervlak, terwyl C. acutatum vanaf Hakea klein hoeveelhede van beide gemelaniseerde en ongemelaniseerde appressoria vorm. Meeste van die appressoria wat deur C. acutatum vanaf Protea gevorm word, vorm op die aanhegtingspunte tussen selle en op die periklinale wande van die epidermale selle. Vanuit hierdie studie is dit duidelik dat C. acutatum f. sp. hakea nie 'n patogeen van Protea is nie. Gevolglik hou die huidige gebruik van hierdie isolaat as biologiese beheer agent van Hakea in Suid-Afrika geen gevaar in vir inheemse Protea spesies nie. Colletotrichum acutatum vanaf Protea (alhoewel dit naverwant is aan C. acutatum f. sp. hakea) is 'n patogeen van Protea en hierdie stelling is ook bevestig deur histologiese waarnemmgs. Ter samevatting het hierdie studie getoon dat verskeie Colletotrichum spesies geassosieer word met siektes van Proteaceae. Hierdie spesies het van mekaar verskil rakende patogenisiteit en aggressiwiteit nadat hulle op sekere protea kultivars geïnokuleer is. Hierdie verskille kon gedeeltelik verklaar word deur die gedrag van C. acutatum op die blaaroppervlaktes van verskillende protea kultivars. Dit is duidelik dat die verspreiding van die verskillende spesies, hulle aggressiwiteit op verskillende Proteaceae en hul infeksie metodes verder ondersoek moet word. Hierdie studie verskaf 'n basis vir toekomstige navorsing rakende lang-termyn effektiewe bestuur van hierdie patogene in fynbos aanplantings.

No description available.

published_or_final_version / Ecology and Biodiversity / Master / Master of Philosophy

Thesis (M. Phil.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 100-117).

Thesis (Ph. D.)--Rutgers University, 2008. / "Graduate Program in Plant Biology." Includes bibliographical references.

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: James A. Hawk, Dept. of Plant & Soil Science. Includes bibliographical references.

No description available.

Made available in DSpace on 2014-06-11T19:32:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2002-07Bitstream added on 2014-06-13T18:43:53Z : No. of bitstreams: 1 peres_nar_dr_botfca.pdf: 1562293 bytes, checksum: 80875212025872cc8702cb8d95533821 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A podridão floral, causada por Colletotrichum acutatum, afeta flores de citros e induz à abscisão de frutos jovens, sendo considerada um sério problema na maioria das áreas úmidas onde se produz citros nas Américas. O controle da doença é feito pela pulverização de fungicidas durante a florada porém, uma das dificuldades é determinar o momento ideal para o controle. Um modelo de previsão foi desenvolvido na Flórida para indicar a necessidade de pulverização, considerando a quantidade de inóculo, chuvas e molhamento foliar. Este modelo foi avaliado durante três anos consecutivos na região de Itapetininga-SP. Verificou-se que mediante a aplicação do modelo obteve-se um bom controle da doença, tendo-se evitado duas pulverizações desnecessárias em comparação com o calendário, em 1999, e uma pulverização, comparado ao esquema do produtor, em 2000 e 2001. Um novo sistema de previsão para controle da podridão floral (PFD-FAD) foi desenvolvido incorporando outros fatores que também influenciam a ocorrência da doença, como o histórico do pomar, a suscetibilidade da variedade, o estágio de desenvolvimento da florada, assim como chuva, molhamento foliar e nível de inóculo, além da data da última... . / Postbloom fruit drop (PFD), caused by Colletotrichum acutatum Simmonds, infects petals of citrus flowers and induces the abscission of fruitlets. The disease can cause serious losses in most humid areas where citrus is produced in the Americas. The disease is controlled by fungicide applications during the bloom but it is difficult to properly time applications. A model was developed in Florida to schedule fungicide applications based on the amount of inoculum and the amount of rainfall and leaf wetness for the last 5 days. This model was evaluated during three consecutive years in Itapetininga-SP, Brazil. Results showed that applications following the model provided good control of the disease and saved two sprays compared to the calendar program in 1999, and one spray compared to the grower’s choice in 2000 and 2001. A new advisory system (PFD-FAD) was developed to be more widely applicable by incorporating risk factors that are inherent in any planting which affected by PFD incidence. The history of the disease in the grove, the varietal susceptibility, the stage of the bloom, as well as the rain, leaf wetness, the amount of inoculum and the last spray date were considered. Field tests in 2001 showed that the system provided good control of the disease with only one fungicide application. Benomyl is considered one of the most effective products for PFD control but despite that C. acutatum is not highly sensitive to benomyl in culture. The mycelial growth and conidial germination is inhibited by 80% at concentration of 1.0 μg/mL, but higher concentrations do not completely inhibit the growth of the fungus. Colletotrichum gloeosporioides, a common saprophyte and causal agent of anthracnose of fruits postharvest, is completely inhibit by 1.0 μg/mL... (Complete abstract, click electronic address below).

Orientadora : Profª. Drª. Sandra Mara Woranovicz Barreira / Coorientador : Prof. Dr. Alan Guilherme Gonçalves / Dissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências da Saúde, Programa de Pós-Graduação em Ciências Farmacêuticas. Defesa: Curitiba, 22/02/2013 / Inclui referências : f. 108-115 / Área de concentração: Insumos, medicamentos e correlatos / Resumo: A inativação fotodinâmica (PDI) consiste em um tipo de intervenção baseado na associação de luz, fotossensibilizador e oxigênio molecular (O2), que resulta na destruição de um alvo biológico específico. Dentre os fotossensibilizadores empregados na PDI, 5,10,15,20-tetraquis(N-metilpiridino-4-il)porfirina (Tetra-Py+ ) tem demonstrado ser efetivo na fotoinativação de diversos micro-organismos. Colletotrichum graminicola é um fitopatógeno que causa antracnose foliar e do colmo em milho (Zea mays L.). C. graminicola é altamente resistente em condições ambientais, sendo também resistente a fungicidas comumente empregados na agricultura. Dessa forma, a antracnose tem causado impacto importante nas culturas de milho do Brasil. Além disso, o uso abusivo de fungicidas na cultura do milho representa um problema de saúde pública. Assim, o objetivo do presente trabalho foi avaliação da fotoinativação de C. graminicola utilizando Tetra-Py +, além de quatro derivados porfirínicos com ambos os grupos N-metil-piridina catiônica meso-ligados e grupos fenil meso-ligados (Tri-Py+, Di -cis-Py+, Di-trans-Py+ e Mono-Py+). Com esse propósito, os experimentos foram realizados empregando suspensões de conídios padronizadas a 105 e 104 conídios / mL. As concentrações dos fotossensibilizadores foram 5, 10, 15 e 25 M e o tempo de irradiação máximo foi ajustado para 20 minutos. Além dos ensaios de fotoinativação, três tipos de experimentos controles foram executados simultaneamente: controle claro, branco e controle escuro. A fotoestabilidade das porfirinas e a produção de oxigênio singlete foram determinadas para todos os compostos. Entre as porfirinas avaliadas, apenas o derivado Di-cis-Py+ demonstrou toxicidade no escuro e, assim, não foi utilizado para estudos de PDI. As outras porfirinas evidenciaram propriedades fotoinativadoras em diferentes níveis, que foram relacionadas com o número de cargas e sua distribuição na estrutura da molécula. Estas características estruturais também refletiram na fotoestabilidade e produção de oxigênio singlete. As porfirinas Tri-Py+ e Di-trans-Py+ demonstraram os melhores resultados, ocorrendo fotoinativação completa na concentração de 5 M, com um tempo de irradiação de cinco minutos. A porfirina Tetra-Py+ mostrou uma propriedade fotoinativadora mais branda, para a qual a fotoinativação total foi evidente na concentração de 50 M, para o mesmo período de cinco minutos irradiação. Por sua vez, a porfirina Mono- Py+ foi o derivado menos eficaz (25 M, 20 minutos), inativando totalmente apenas a suspensão de conídios menos concentrada. Como conclusão, a fotoinativação de C. graminicola empregando meso-tetra-arilporfirinas catiônicas como fotossensibilizadores ocorreu em níveis significativos, demonstrando a possibilidade de utilização desses compostos em associação com a luz solar para inativação do micro-organismo. Esse processo pode contribuir para o controle da antracnose na cultura do milho no Brasil. Palavras-chave: Porfirinas. Síntese química. Inativação fotodinâmica. Colletotrichum. / Abstract: Photodynamic inactivation (PDI) is a type of intervention based on the association of light, photosensitizer and molecular oxygen (O2), which results in the destruction of a specific biological target. Among the photosensitizers utilized in PDI, 5,10,15,20- tetrakis(N-methyl pyridinium-4-yl)porphyrin (Tetra-Py+ ) has demonstrated to be effective in the photoinactivation of diverse microorganisms. Colletotrichum graminicola is a fungal pathogen that causes leaf and stalk anthracnose in maize (Zea mays). C. graminicola is highly resistant under environmental conditions, being also resistant to fungicides commonly used in agriculture. In this way, anthracnose has caused an important impact in Brazil's maize crops. In addition, the abusive use of fungicides in maize cultivation represents a public health issue. Thus, the objective of the present work was the evaluation of C. graminicola photoinactivation using Tetra-Py+, plus four porphyrin-derivatives having both meso-linked N-methyl-pyridine cationic centers and meso-linked phenyl groups (Tri-Py+, Di-trans-Py+, Di-cis-Py+ and Mono-Py+). For this purpose, experiments were performed with standardized conidial suspensions at 105 and 104 conidia/mL. The concentrations of the photosensitizers were 5, 10, 15 and 25 ?M and the maximum irradiation time was set to 20 minutes. In addition to the photoinactivation assays, three types of control experiments were simultaneously executed: blank, light control and dark control. Porphyrin photo-stability and production of oxygen singlet were also determined for all compounds. Among the porphyrins herein evaluated, only Di-cis- Py+ derivative demonstrated toxicity in the dark and thereby it was not employed for PDI studies. The other porphyrins presented photoinactivating properties at varying levels that were related to the number of charges and their distribution in the molecule structure. These structural features also reflected in the photo-stability and singlet oxygen production. Porphyrins Tri-Py+ and Di-trans-Py+ demonstrated the best results, giving complete photoinactivation at 5 ?M with an irradiation time of five minutes. Porphyrin Tetra-Py+ showed a milder photoinactivation property, which was complete at 50 ?M with the same irradiation time. Porphyrin Mono-Py+ was the least effective derivative (25 ?M, twenty minutes), resulting in total inactivation only for the less concentrated conidial suspension. In conclusion, the photoinactivation of C.. graminicola using cationic meso-substituted porphyrins occurred in significant levels, demonstrated the possibility of using these compounds in combination with sunlight for inactivation of microorganism. This process may contribute to the control of maize anthracnose qin Brazil. Key-words: Porphyrins. Chemical synthesis. Photodynamic inactivation. Colletotrichum

Orientador: Nilton Luiz de Souza / Resumo: A podridão floral, causada por Colletotrichum acutatum, afeta flores de citros e induz à abscisão de frutos jovens, sendo considerada um sério problema na maioria das áreas úmidas onde se produz citros nas Américas. O controle da doença é feito pela pulverização de fungicidas durante a florada porém, uma das dificuldades é determinar o momento ideal para o controle. Um modelo de previsão foi desenvolvido na Flórida para indicar a necessidade de pulverização, considerando a quantidade de inóculo, chuvas e molhamento foliar. Este modelo foi avaliado durante três anos consecutivos na região de Itapetininga-SP. Verificou-se que mediante a aplicação do modelo obteve-se um bom controle da doença, tendo-se evitado duas pulverizações desnecessárias em comparação com o calendário, em 1999, e uma pulverização, comparado ao esquema do produtor, em 2000 e 2001. Um novo sistema de previsão para controle da podridão floral (PFD-FAD) foi desenvolvido incorporando outros fatores que também influenciam a ocorrência da doença, como o histórico do pomar, a suscetibilidade da variedade, o estágio de desenvolvimento da florada, assim como chuva, molhamento foliar e nível de inóculo, além da data da última... (Resumo completo, clicar acesso eletrônico abaixo). / Abstract: Postbloom fruit drop (PFD), caused by Colletotrichum acutatum Simmonds, infects petals of citrus flowers and induces the abscission of fruitlets. The disease can cause serious losses in most humid areas where citrus is produced in the Americas. The disease is controlled by fungicide applications during the bloom but it is difficult to properly time applications. A model was developed in Florida to schedule fungicide applications based on the amount of inoculum and the amount of rainfall and leaf wetness for the last 5 days. This model was evaluated during three consecutive years in Itapetininga-SP, Brazil. Results showed that applications following the model provided good control of the disease and saved two sprays compared to the calendar program in 1999, and one spray compared to the grower's choice in 2000 and 2001. A new advisory system (PFD-FAD) was developed to be more widely applicable by incorporating risk factors that are inherent in any planting which affected by PFD incidence. The history of the disease in the grove, the varietal susceptibility, the stage of the bloom, as well as the rain, leaf wetness, the amount of inoculum and the last spray date were considered. Field tests in 2001 showed that the system provided good control of the disease with only one fungicide application. Benomyl is considered one of the most effective products for PFD control but despite that C. acutatum is not highly sensitive to benomyl in culture. The mycelial growth and conidial germination is inhibited by 80% at concentration of 1.0 μg/mL, but higher concentrations do not completely inhibit the growth of the fungus. Colletotrichum gloeosporioides, a common saprophyte and causal agent of anthracnose of fruits postharvest, is completely inhibit by 1.0 μg/mL... (Complete abstract, click electronic address below). / Doutor