Among the environmental airborne fungi one of the most common is <i>Alternaria alternata</i>. From a clinical perspective Alternaria has long been associated with IgE-mediated, histamine-dependent mold allergy, allergic rhinitis, chronic rhinosinusitis (CRS) and asthma. Recently it has been proven that an abnormal immunological response to Alternaria most likely contributes to the pathogenesis of upper respiratory airway disorders. In this body of work, we present for the first time results of several sets of experiments including, 1) the analysis of A. alternata spore germination expressed sequence tags (ESTs), 2) the survey of global allergen homologues in fungal genomes, and 3) the first microarray experiment investigating airway epithelial cell responses to this fungus. In the first project, the analyses of the EST dataset offered a first look into the gene content of A. alternata and represents the beginning of future research of this ubiquitous fungus. Annotation and classification of ESTs revealed a number of genes that could be involved in the immunomodulation process of the human immune response toward fungi. We also discovered that the majority of known allergens are expressed during the spore germination phase of A. alternata. For investigating the allergenic potential of fungi we developed a whole genome approach by querying fungal genome sequences (<i>A. alternata, A. brassicicola,</i> and <i>Aspergillus fumigatus</i>) with a database of all known allergenic proteins from a taxonomically diverse group of organisms. Interestingly, we identified homologues of diverse types of allergens in these fungal genomes and also many homologues of allergens from other organisms including those from pollen, insects, and venoms. Finally, we investigated global gene expression changes of human airway cells in response to <i>A. alternata</i> and an ∆alt a 1 deletion mutant. We found that wild type Alternaria spores induced significant changes in gene expression patterns in human airway epithelial cells, especially known immune response genes. Furthermore, results of these analyses revealed that Alt a 1 is a major factor in inducing epithelial inflammatory responses. / Ph. D.

A foliar pathogen identified as a member of the genus Alternaria was isolated from blighted Sphenoclea zeylanica (gooseweed) collected in 1991 from a rice field near Los Banos, Laguna, Philippines. Inoculum density, dew period, and plant height are factors influencing biocontrol of S. zeylanica with this indigenous pathogen. Significantly higher percent reductions in plant height and dry weight were obtained and all plants were killed at higher inoculum concentrations with 8 h of dew. The number, germination, and virulence of conidia were significantly affected by production techniques, temperature, light condition, and incubation period. Exposure to continuous near-ultraviolet (NUV) light at 28$ sp circ$C stimulated sporulation on agar media and on solid substrates. Overall, the best production technique was the use of sorghum seeds using an equal quantity of sorghum seeds and water (w/v) incubated for four weeks. Another conidia production method using the sporulation medium (S-medium) technique was evaluated with the addition of 20 g L$ sp{-1}$ of calcium carbonate (CaCO$ sb3)$ and 2 ml of sterile distilled water. Primary 1/2 PDA at 18$ sp circ$C in the dark produced the most virulent conidia. This technique produced conidia relatively rapid, but was labour intensive. Host range studies using 49 plant species in 40 genera representing 20 families, selected by using a modified centrifugal phylogenetic and variety strategy indicated that only S. zeylanica was susceptible in the absence and presence of supplemental dew. On the basis of morphological and cultural characteristics, pathogenicity on the host, host specificity, and the absence of a previous record of this fungal pathogen on S. zeylanica, the binomial A. alternata f. sp. sphenocleae is proposed.

Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains viii, 70 p. : ill. Includes abstract. Includes bibliographical references (p. 64-70).

TA and TB toxins are host-specific phytotoxins produced by the fungus Alternaria alternata f. sp. Iycopersici, the causative agent of Alternaria stem canker disease in tomato. Both compounds are isolated as an equilibrium mixture of the esters formed by either the C(13) or C(14) hydroxy groups with the Re prochiral carboxy group of tricarballylic acid. The design and execution of syntheses for these toxins is necessary in order to study structure-function relationships for T A and TB toxins and their application as natural herbicides. The aim of the synthetic study presented in this thesis is to develop and implement a methodology for the synthesis of the C(1)-C(9) unit of the C17 amino¬pentol backbone of the TA and TB toxins with the required functional groups and appropriate stereochemistry using a chiral sulfoxide as an auxiliary to control the stereochemistry in key steps of the synthetic route. (2R,4S,5R,6R)-2,6-Dimethyloctane-1 ,4,5-triol, synthon B, and (2S,4R,5R)-1-aminononane-2,4,5,9-tetrol, synthon A were identified by retrosynthetic analysis of the C17 aminopentol backbone of TA toxin as key intermediates for a proposed synthesis. Further analysis of synthon B identified a C5 synthon that can be obtained from (2S)-malic acid by functional group transformations, chiral sulfoxide methodo¬logy and an appropriate protective group strategy. The work presented in the thesis shows that a protected intermediate corresponding to the abovementioned C5 synthon, (2S,4S)-2,4,5-trihydroxy:-pentanal can be prepared from (2S)-malic acid, but that using either Sharpless methodology or chiral sulfoxide methodology for the introduction of the third stereogenic centre and chain extension to a C9 unit, failed as a result of the steric crowding caused by the acetonide protecting group. As a result a different synthetic route is proposed. The results obtained in the work on TA toxin were applied to the synthesis of the C(1)-C(9) aminotetrol unit of the backbone of TB toxin. / Dissertation (MSc (Chemistry))--University of Pretoria, 2007. / Chemistry / unrestricted

No description available.

No description available.

Using the genome database of the phytopathogenic fungus, Alternaria brassicicola, we identified a gene with high homology to the cell wall integrity-associated mitogen-activated protein (MAP) kinase, Slt2 in the yeast, Saccharomyces cerevisiae. This MAP kinase consists of a predicted 1,251-bp open reading frame, and encodes a 416-amino-acid protein weighing 47501 Da. This homolog was designated AbSlt2 (A. brassicicola Slt2) and gene disruption knockout (KO) mutants were generated in an A. brassicicola wild type background. Several altered phenotypes were found in the mutants compared to the wild type. During growth in various liquid and solid media, the abslt2 mutants displayed slightly aberrant hyphal growth and were unable to develop at the same rate as wild type. Furthermore, scanning electron microscopy (SEM) analysis revealed the abslt2 mutants showed decreased penetration ability, underdeveloped appresoria, and altered morphology on the leaf surface of the host plant, Brassica oleracea (cabbage) when compared to wild type. Abslt2 mutant hyphae exhibited slower growth in planta ultimately resulting in highly reduced virulence. Complementation of the disruption mutant with the wild type gene fully restored pathogenicity. Therefore, AbSlt2 is a new pathogenicity and developmental factor in A. brassicicola. / Master of Science

Resumo: A mancha marrom de alternaria, causada pela Alternaria alternata f. sp. citri, afeta o tangor murcote causando lesões em folhas, ramos e frutos, acarretando em desfolha e manchas que depreciam o fruto comercialmente. Os objetivos deste trabalho foram verificar o efeito do meio de cultura no isolamento, da temperatura e do fotoperíodo no crescimento micelial do patógeno, avaliar a sensibilidade do patógeno à fungicidas in vitro e estabelecer o melhor produto e dose para o controle da doença no campo. As avaliações laboratoriais constaram de avaliações de crescimento micelial, medição do tamanho de conídios, concentração de conídos/mL e avaliação de meios de culturas para isolamento do patógeno. Os resultados do teste in vitro mostraram que os ingredientes ativos trifloxystrobin, iprodione, azoxystrobin, difenoconazole, pyraclostrobin, trifloxystrobin + propiconazole e trifloxystrobin + tebuconazole inibiram completamente o crescimento micelial do patógeno. No ensaio de campo todos os tratamento foram superiores a testemunha quanto a produtividade. Concluindo que o controle da doença é recomendado independente do produto utilizado. Entre os produtos utilizados o tratamento com trifloxystrobin + propiconazole foi rentável comparando-se custo e produtividade. / Abstract: The brown spot caused by Alternaria alternata f. sp. citri, affects the Murcott tangor causing lesions in leaves, branches and fruits, defoliation and depreciating the fruit commercially. The objectives of this work went to determine the influence of temperature, media culture and sensibility several fungicides and rates in vitro and in the field. The results showed that: In in vitro test the ingredients active trifloxystrobin, iprodione, azoxystrobin, difenoconazole, pyraclostrobin, trifloxystrobin + propiconazole and trifloxystrobin + tebuconazole inhibited the micelial growth of the pathogen completely. In the field all fungicides treatments were effectives with productivity. Among the used products the treatment trifloxystrobin + propiconazole was profitable being compared cost and productivity. / Orientador: Edson Luiz Furtado / Coorientador: Wilson Story Venâncio / Banca: Nilton Luiz de Souza / Banca: Maristella Dalla Pria / Mestre

Made available in DSpace on 2014-06-11T19:28:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-02-13Bitstream added on 2014-06-13T18:34:58Z : No. of bitstreams: 1 colturato_ab_me_botfca.pdf: 564408 bytes, checksum: 3f2cf7349d1ab5666c1d31ddf84e982f (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A mancha marrom de alternaria, causada pela Alternaria alternata f. sp. citri, afeta o tangor murcote causando lesões em folhas, ramos e frutos, acarretando em desfolha e manchas que depreciam o fruto comercialmente. Os objetivos deste trabalho foram verificar o efeito do meio de cultura no isolamento, da temperatura e do fotoperíodo no crescimento micelial do patógeno, avaliar a sensibilidade do patógeno à fungicidas in vitro e estabelecer o melhor produto e dose para o controle da doença no campo. As avaliações laboratoriais constaram de avaliações de crescimento micelial, medição do tamanho de conídios, concentração de conídos/mL e avaliação de meios de culturas para isolamento do patógeno. Os resultados do teste in vitro mostraram que os ingredientes ativos trifloxystrobin, iprodione, azoxystrobin, difenoconazole, pyraclostrobin, trifloxystrobin + propiconazole e trifloxystrobin + tebuconazole inibiram completamente o crescimento micelial do patógeno. No ensaio de campo todos os tratamento foram superiores a testemunha quanto a produtividade. Concluindo que o controle da doença é recomendado independente do produto utilizado. Entre os produtos utilizados o tratamento com trifloxystrobin + propiconazole foi rentável comparando-se custo e produtividade. / The brown spot caused by Alternaria alternata f. sp. citri, affects the Murcott tangor causing lesions in leaves, branches and fruits, defoliation and depreciating the fruit commercially. The objectives of this work went to determine the influence of temperature, media culture and sensibility several fungicides and rates in vitro and in the field. The results showed that: In in vitro test the ingredients active trifloxystrobin, iprodione, azoxystrobin, difenoconazole, pyraclostrobin, trifloxystrobin + propiconazole and trifloxystrobin + tebuconazole inhibited the micelial growth of the pathogen completely. In the field all fungicides treatments were effectives with productivity. Among the used products the treatment trifloxystrobin + propiconazole was profitable being compared cost and productivity.

A mancha de Alternaria causada pelo fungo Alternaria helianthi, é uma das doenças com maior potencial de dano na cultura do girassol no Brasil, uma vez que as condições climáticas favoráveis ao seu desenvolvimento coincidem com as principais épocas de plantio desta cultura. Considerando-se a importância da fotossíntese para as plantas, os patógenos podem interferir, inicialmente causando clorose, até atingir grandes áreas foliares com lesões necróticas, levando à perda de tecido e à desfolha. Para quantificar os efeitos da doença em folhas de girassol, foi medida a taxa de fotossíntese líquida (A) de folhas sadias e de folhas doentes durante o ciclo de crescimento da cultura, em duas épocas distintas de plantio. Através de uma equação matemática, a severidade da doença foi relacionada à fotossíntese ('&#946;'). Analisou-se, para o patossistema Girassol x Alternaria, a influência do patógeno nas áreas verdes remanescentes do tecido foliar. Foi observada redução das taxas fotossintéticas dos tecidos verdes remanescentes das folhas doentes, comprovando-se que existe lesão virtual para o patossistema Girassol x Alternaria. Os valores de '&#946;' encontrados variaram de 1,4 a 4,7, indicando que as épocas de plantio têm influência sobre a severidade da doença. Observou-se que folhas ainda sem lesões de plantas doentes apresentaram comprometimento fotossintético / The Alternaria blights in sunflower caused by the fungus Alternaria helianthi is one of the major diseases that affects sunflower in Brazil. The effects of them upon net photosynthetic rate of four different sunflower genotypes leaves were measured in the field. Alternaria blights reduced photosynthesis not only through a reduction in green leaf area, but also through an effect on photosynthesis of the remaining green leaf tissue. A mathematics approach was derived to relate the infected leaf area with net photosynthetic rate (&#946;). This relationship was used to analyse the pathosystem Sunflower x Alternaria. For all genotypes studied, a decrease in the photosynthetic rates of infected leaves was observed when compared to healthy leaves. ln addition, reduction in photosynthesis was observed in the remaining green leaf tissue of infected plants proving the existence of virtual lesions in sunflower leaves when infected by Alternaria helianthi. Values of &#946; ranged from 1,4 to 4,7, showing that season of planting has a strong influence upon severity of the disease.