Protocolo de tecnologia: selecao para resistencia a doencas em hortalicas. 5. Tomateiro - Pinta-preta (Alternaria solani).

1999

Mancha marrom de alternaria em tangerinas.

O primeiro relato sobre Alternaria em citros foi em 1903, na Austrália, mas há registros da doença em Israel, Turquia, Espanha, Colômbia, África do Sul e Estados Unidos. No Brasil, a primeira constatação da doença afetando exclusivamente tangerinas foi em 2001, no Rio de Janeiro, estando hoje disseminada em vários estados. A identificação da doença foi realizada em frutos de tangor ?Murcott? e tangerina ?Ponkan? e é causada pelo fungo Alternaria alternata f. sp. citri, que produz uma toxina específica para tangerinas e seus híbridos, não afetando laranjas doces, limões e limas ácidas.

Microscopia eletrônica de varredura da interação Alternaria solani - tomateiro suscetível e resistente.

Objetivando analisar os eventos iniciais das interações A. solani - L. hirsutum var. glabratum e A. solani - L. esculentum ev. Miller, será realizado um trabalho utilizando processamento para microscopia eletrônica de varredura.

Reação de genótipos de girassol à mancha de alternaria (alternariaster helianthi) em condições de campo, nas safras 2013/2014 e 2014/2015.

RESUMO: A reação de 23 genótipos de girassol à mancha de Alternaria foi avaliada em dois experimentos de campo, conduzidos em Londrina, PR, nas safras 2013/2014 e 2014/2015. Os experimentos foram semeados em outubro de 2013 e outubro de 2014. A severidade da doença, que ocorreu por infecção natural das plantas pelo fungo, foi avaliada na fase de desenvolvimento R3, utilizando uma escala diagramática da doença. Após a colheita, também foram avaliados a produtividade, o peso de mil aquênios e o teor de óleo. Em cada experimento, verificou-se diferença estatística significativa entre os híbridos avaliados em condições de campo, tanto para a severidade da doença, quanto para os componentes de produção. Nenhum genótipo de girassol apresentou resistência completa à mancha de Alternaria. ABSTRACT: The reaction of 23 sunflower genotypes to Alternaria leaf spot disease was evaluated in two field experiments carried out in Londrina, state of Paraná, Brazil, during 2013/2014 and 2014/2015 growing seasons. The experiments were sown in October 2013 and October 2014. Alternaria disease severity, under natural conditions in the field, was evaluated at the R3 growth stage with reference to a diagrammatic scale developed for this disease. After harvesting, yield, 1000-seed weight and oil content were also evaluated. For each experiment, statistical significance was observed among the evaluated genotypes for disease severity and yield components. None of the sunflower genotypes showed complete resistance to Alternaria leaf spot.

Severidade de mancha de alternaria em genótipos de girassol no Cerrado do Distrito Federal.

RESUMO: Este trabalho teve como objetivo comparar a severidade da mancha de Alternaria de genótipos de girassol em ambientes do Cerrado do Distrito Federal. Três experimentos foram avaliados, dois na Embrapa Cerrados (Planaltina, DF) e um localizado na Embrapa Produtos e Mercado (Recanto das Emas, DF). Foram feitas análises ao longo do ciclo da cultura com um intervalo de 15 dias, sendo a primeira aos 35 dias após emergência. Cada planta foi analisada em três partes: terço inferior, terço médio e terço superior. Ao final de cada experimento, a área abaixo da curva de progresso da doença (AACPD) foi calculada para cada genótipo. De acordo com os resultados observados, o ambiente de sequeiro na Embrapa Cerrados, que deteve a maior média da severidade da doença, entre os ambientes avaliados. Dentre os genótipos avaliados, MG 360 mostrou menor severidade da doença no sequeiro e AGUARA 06 no irrigado da Embrapa Cerrados. O genótipo BSG 42 na Embrapa Produtos e Mercado, se destacou pela menor severidade do fungo. Houve influência significativa do ambiente nos resultados de severidade da doença, que está estreitamente relacionada com os fatores climáticos como temperatura e umidade relativa do ar. A compreensão dessas condições favoráveis ao desenvolvimento do fungo é essencial quando se avalia a resistência em genótipos de girassol. ABSTRACT: This study had the purpose of comparing the severity of Alternaria leaf spot on genotypes of sunflower in the Brazilian Cerrado. Three field trials were established, two at Embrapa Cerrados (Planaltina, DF) and one at Embrapa Produtos e Mercados (Recanto das Emas, DF). Evaluations were made during the crop cycle every 15 days, the first one happening 35 days after crop emergency. Each plant was analyzed in three parts: lower, middle and upper thirds. At the end of each trial the average area under the disease progress curve (AUDPC), for each third, was calculated for all genotypes. According to the observed results, the dryland environment at Embrapa Cerrados had the highest mean disease severity, among the studied environments. Between the evaluated genotypes, MG360 showed less severity in dryland and AGUARA 06 in the irrigated environment at Embrapa Cerrados. At Embrapa Produtos e Mercado the genotype that presented the best performance was BRS G42. Environmental conditions deeply affected the trials, mainly temperature and relative humidity. Their influence on Alternaria leaf spot epidemics in the Cerrado region must be studied in more detail, to avoid misinterpreting data when evaluating sunflower genotypes for resistance to this important fungal disease.

Isolation of Alternaria alternata from an emollient cream:implications for public health

A specimen of emollient cream, which was observed to be contaminated peripherally with a filamentous fungus was examined for the presence of fungi and the resulting fungal colonies were examined phenotypically and genotypically. Subsequent DNA extraction and PCR amplification of the large internal transcribed spacer region [ITS1-5.8S-ITS2] yielded an amplicon of 512 bp. Sequence analysis identified this as Alternaria alternata at the 100% homology level with all 512/512 bases called. This organism has been previously reported as a cause of opportunistic infections involving skin and immunocompromised patients. This is the first report of an emollient cream as a source of this organism. It highlights the need for proper management of such preparations in order to minimize the potential spread of fungi to susceptible patient populations.

Molecular characterisation of Alternaria linicola and its detection in linseed

Nucleotide sequences of the ribosomal DNA (rDNA) internal transcribed spacers (ITS) 1 and 2 and a 1068 bp section of the beta-tubulin gene divided seven designated species of Alternaria into five taxa. Stemphylium botryosum formed a sixth closely related taxon. Isolates of A. linicola possessed an identical ITS sequence to one group of A. solani isolates, and two clusters of A. linicola isolates, revealed from beta-tubulin gene data to show minor variation, were as genetically similar to isolates of A. solani as they were to each other. We suggest, therefore, that A. linicola falls within the species A. solani. Similar results suggest that A. lini falls within the species A. alternata. RAPD analysis of the total genomic DNA from the Alternaria spp. concurred with the nucleotide sequence analyses. An oligonucleotide primer (ALP) was selected from the rDNA ITS1 region of A. linicola/A. solani. PCR with primers ALP and ITS4 (from a conserved region of the rDNA) amplified a c. 536 bp fragment from isolates of A. linicola and A. solani but not from other Alternaria spp. nor from other fungi which may be associated with linseed. These primers amplified an identical fragment, confirmed by Southern hybridization, from DNA released from infected linseed seed and leaf tissues. These primers have the potential to be used also for the detection of A. solani in host tissues.

Atmospheric Concentrations of Alternaria, Cladosporium, Ganoderma and Didymella Spores Monitored in Cork (Ireland) and Worcester (England) During the Summer of 2010

This study represents the first international intercomparison of fungal spore observations since 1990, focusing on atmospheric concentrations of Alternaria, Cladosporium, Ganoderma and Didymella spores. The campaigns were performed at sites located in Cork (Ireland) and Worcester (England) during summer 2010. Observations were made using Hirst-type volumetric spore traps and corresponding optical identification at the genus level by microscope. The measurements at both sites (including meteorological parameters) were compared and contrasted. The relationships between the fungal spore concentrations with selected meteorological parameters were investigated using statistical methods and multivariate regression trees (MRT). The results showed high correlations between the two sites with respect to daily variations. Statistically significant higher spore concentrations for Alternaria, Cladosporium and Ganoderma were monitored at the Worcester site. This result was most likely due to the differences in precipitation and local fungal spore sources at the two sites. Alternaria and Cladosporium reached their maxima a month earlier in Cork than in Worcester, and Didymella with Ganoderma peaked simultaneously with similar diurnal trends found for all the investigated spore types. MRT analysis helped to determine threshold values of the meteorological parameters that exerted most influence on the presence of spores: they were found to vary at the two sites. Our results suggest that the aeromycological profile is quite uniform over the British Isles, but a description of bioaerosols with respect to overall load and daily concentration can be quite diverse although the geographical difference between sites is relatively small. These variations in the concentrations therefore need to be explored at the national level

Determination of Alternaria spp. Habitats Using 7-Day Volumetric Spore Trap, Hybrid Single Particle Lagrangian Integrated Trajectory Model and Geographic Information System

There are many species among the Alternaria genus, which hosts on economically important crops causing significant yield losses. Less attention has been paid to fungi hosting on plants constituting substantial components of pastures and meadows. Alternaria spp. spores are also recognised as important allergens. A 7-day volumetric spore trap was used to monitor the concentration of airborne fungal spores. Air samples were collected in Worcester, England (2006–2010). Days with a high spore count were then selected. The longest episode that occurred within a five year study was chosen for modelling. Two source maps presenting distribution of crops under rotation and pastures in the UK were produced. Back trajectories were calculated using the HYSPLIT model. In ArcGIS clusters of trajectories were studied in connection with source maps by including the height above ground level and the speed of the air masses. During the episode no evidence for a long distance transport from the continent of Alternaria spp. spores was detected. The overall direction of the air masses fell within the range from South-West to North. The back trajectories indicated that the most important sources of Alternaria spp. spores were located in the West Midlands of England.

Potential Sources of Airborne Alternaria spp. spores in South-west Spain

Fungi belonging to the genus of Alternaria are recognised as being significant plant pathogens, and Alternaria allergens are one of themost important causes of respiratory allergic diseases in Europe. This study aims to provide a detailed and original analysis of Alternaria transport dynamics in Badajoz, SW Spain. This was achieved by examining daily mean and hourly observations of airborne Alternaria spores recorded during days with high airborne concentrations of Alternaria spores (N100 s m−3) from 2009 to 2011, as well as four inventory maps of major Alternaria habitats, the overall synoptic weather situation and analysis of air mass transport using Hybrid Single Particle Lagrangian Integrated Trajectory model and geographic information systems. Land use calculated within a radius of 100 km from Badajoz shows that crops and grasslands are potentially the most important local sources of airborne Alternaria spores recorded at the site. The results of back trajectory analysis showthat, during the examined four episodes, the two main directions where Alternaria source areas were located were: (1) SW–W; and (2) NW–NE. Regional scale and long distance transport could therefore supplement the airborne catch recorded at Badajoz with Alternaria conidia originating from sources such as crops and orchards situated in other parts of the Iberian Peninsula.

Investigating and Predicting Atmospheric Concentrations of Allergenic Fungal Spores (Alternaria, Cladosporium, Didymella and Ganoderma)

Air quality is an increasing concern of the European Union, local authorities, scientists and most of all inhabitants that become more aware of the quality of the surrounding environment. Bioaerosols may be consisted of various elements, and the most important are pollen grains, fungal spores, bacteria, viruses. More than 100 genera of fungal spores have been identified as potential allergens that cause immunological response in susceptible individuals. Alternaria and Cladosporium have been recognised as the most important fungal species responsible for respiratory tract diseases, such as asthma, eczema, rhinitis and chronic sinusitis. While a lot of attention has been given to these fungal species, a limited number of studies can be found on Didymella and Ganoderma, although their allergenic properties were proved clinically. Monitoring of allergenic fungal spore concentration in the air is therefore very important, and in particular at densely populated areas like Worcester, UK. In this thesis a five year spore data set was presented, which was collected using a 7-day volumetric spore trap, analysed with the aid of light microscopy, statistical tests and geographic information system techniques. Although Kruskal-Wallis test detected statistically significant differences between annual concentrations of all examined fungal spore types, specific patterns in their distribution were also found. Alternaria spores were present in the air between mid-May/mid-June until September-October with peak occurring in August. Cladosporium sporulated between mid-May and October, with maximum concentration recorded in July. Didymella spores were seen from June/July up to September, while peaks were found in August. Ganoderma produced spores for 6 months (May-October), and maximum concentration could be found in September. With respect to diurnal fluctuations, Alternaria peaked between 22:00h and 23:00h, Cladosporium 13:00-15:00h, Didymella 04:00-05:00h and 22:00h-23:00h and Ganoderma from 03:00h to 06:00h. Spatial analysis showed that sources of all fungal species were located in England, and there was no evidence for a long distance transport from the continent. The maximum concentration of spores was found several hours delayed in comparison to the approximate time of the spore release from the crops. This was in agreement with diurnal profiles of the spore concentration recorded in Worcester, UK. Spores of Alternaria, Didymella and Ganoderma revealed a regional origin, in contrast to Cladosporium, which sources were situated locally. Hence, the weather conditions registered locally did not exhibit strong statistically significant correlations with fungal spore concentrations. This has had also an impact on the performance of the forecasting models. The best model was obtained for Cladosporium with 66% of the accuracy.

Cutaneous Infection by Different Alternaria Species in a Liver Transplant Recipient

Fungal invasive infections are rare in general population but are an emergent cause of infection in the immunocompromized population, especially in the solid organ transplant recipients. Herein the authors report a clinical case of a liver transplanted patient suffering a cutaneous co-existent infection with A. alternata as well as A. infectoria. To our knowledge this is the first case of cutaneous concomitant infection due to those two species reported not only in Portugal but also worldwide. The patient was treated with surgical excision of the lesions and oral itraconazol without relapse.

Effects of gamma radiation on the growth of Alternaria alternata and on the production of alternariol and alternariol monomethyl ether in sunflower seeds

The objective of the present study was to evaluate the effects of different gamma radiation doses on the growth of Alternaria alternata and on the production of toxins alternariol (AOH), and alternariol monomethyl ether (AME) in sunflower seed samples. After irradiation with 2, 5 and 7 kGy, the spore mass was resuspended in sterile distilled water and the suspension was inoculated into sunflower seeds. The number of colony-forming units per gram (CFU/g) was determined after culture on Dichloran Rose Bengal Chloramphenicol and Dichloran Chloramphenicol Malt Extract Agar. The presence of AOH and AME was investigated by liquid chromatography coupled to mass spectrometry. The radiation doses used resulted in a reduction of the number of A. alternata CFU/g and of AOH and AME levels when compared to the nonirradiated control group. Maximum reduction of the fungus (98.5%) and toxins (99.9%) was observed at a dose of 7 and 5 kGy, respectively. Under the present conditions, gamma radiation was found to be an alternative for the control of A. alternata and, consequently, of AOH and AME production in sunflower seeds. (C) 2009 Elsevier Ltd. All rights reserved.

Effects of gamma-radiation on the fungus Alternaria alternata in artificially inoculated cereal samples

The objective of this study was to evaluate the effects of different gamma-radiation doses on the growth of Alternaria alternata in artificially inoculated cereal samples. Seeds and grains were divided into four groups: Control Group (not irradiated), and Groups 1, 2 and 3, inoculated with an A. alternata spore suspension (1 x 10(6) spores/mL) and exposed to 2, 5 and 10 kGy, respectively. Serial dilutions of the samples were prepared and seeded on DRBC (dichloran rose bengal chloramphenicol agar) and DCMA (dichloran chloramphenicol malt extract agar) media, after which the number of colony-forming units per gram was determined in each group. In addition, fungal morphology after irradiation was analyzed by scanning electron microscopy (SEM). The results showed that ionizing radiation at a dose of 5 kGy was effective in reducing the growth of A. alternata. However, a dose of 10 kGy was necessary to inhibit fungal growth completely. SEM made it possible to visualize structural alterations induced by the different gamma-radiation doses used. (C) 2009 Elsevier Ltd. All rights reserved.

Susceptibility of citrus species to Alternaria alternata, the causal agent of the Alternaria brown spot

Alternaria alternata, the causal agent of Alternaria brown spot (ABS), causes necrosis on leaves, twigs, and fruit, reducing the productivity and quality of fruits. Tangerines and their hybrids are highly susceptible to the disease. Species, hybrids, and cultivars of Citrus from the germplasm bank of the Estacao Experimental de Citricultura de Bebedouro, São Paulo, Brazil, were evaluated in 2004 and 2005 with respect to their resistance to A. alternata, both through natural infection and by inoculation. Detached leaves were also used to demonstrate susceptibility or resistance to the disease. Ten cultivars of Satsumas (Citrus unshiu), and 14 cultivars of Clementine mandarin (C. clementina) did not show any symptoms of the disease in their leaves, either through natural infection or when inoculated in the field. The Burguess SRA-412, Wallent SRA-438, Carvalhais, Ampefy SRA-459, Ananas SRA, and Macaque SRA-426 mandarin hybrids (C. reticulata) did not show symptoms of the disease under natural or artificial infection in the field. Some cultivars of C. deliciosa, C. tangerina, C. erythrosa, and C. temple showed symptoms of the disease, even though no previous record of their susceptibility to Alternaria brown spot had been previously reported. The hybrids Fairchild, Nova, Page, Fortune, and Sunburst were susceptible to the disease. However, Fremont mandarin (a crossing between C. clementina and C. reticulata), Encore (C. nobilis x C. deliciosa), and Fallglo (C. reticulata x C. paradisi) did not show symptoms in field, and few symptoms were verified in detached leaves. These materials are promising for the cultivation of tangerines, and will enable genetic improvement for the development of cultivars resistant to Alternaria brown spot. (c) 2007 Elsevier B.V. All rights reserved.