Academic literature on the topic 'Pithomyces chartarum'

Pithomyces chartarum (Berk. & Curt.) M. B. Ellis was isolated from bluegrass sod (Poa pratensis L.) in Illinois, Indiana, and Wisconsin during July and August 1986. This is the first report of Pithomyces chartarum in the north central United States and the first report of the fungus in bluegrass sod. The fungus appears to be a saprophyte on senescent bluegrass leaves; its interest as a possible mycotoxin producer is underlined.

Smooth bromegrass (Bromus inermis Leyss.) is the most common perennial grass species cultivated for forage in North America. During late fall of 2004, smooth bromegrass plants in Lincoln, NE were observed to have brown lesions on leaf midveins that were several centimeters long. Symptomatic leaves were surface disinfested for 1 min in 2% NaOCl and incubated at 25°C on potato dextrose agar (PDA) and water agar. The fungus, Pithomyces chartarum (Berk. & Curt) Ellis, was isolated consistently and identified on the basis of morphological characteristics (1). Colonies were effused and black on PDA. Conidiophores measured 3.5 to 8 × 1.9 to 3.9 μm and were smooth and single. Conidia (7 to 25 × 9.5 to 14 μm) were broadly ellipsoidal, pale brown to dark brown, verrucose with mainly three transverse septa and one to two longitudinal septa. Pathogenicity tests were conducted on 50-day-old plants by spraying with a conidial suspension (2.5 × 105 spores per ml). Control plants were sprayed with sterile water. All plants were kept in a moist chamber (100% relative humidity) for 3 days and then transferred to a greenhouse (25°C, >70% relative humidity, and a 12-h photoperiod). One week after spraying, elongated lesions developed on leaf midveins of inoculated plants from which P. chartarum was consistently reisolated. No symptoms were observed on control plants. While P. chartarum has been described as a saprotroph or a parasite on a wide range of plants primarily in the tropics and subtropics, including the southern United States (2), it was reported previously on B. inermis only in Canada (3). This report expands the distribution and host range of P. chartarum as a pathogen in the United States. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute, Kew, Surrey, England, 1971. (2) D. F. Farr et al. Fungal Databases, Systematic Botany and Mycology Laboratory, On-line publication. ARS, USDA, 2005. (3) J. H. Ginns. Compendium of Plant Disease and Decay Fungi in Canada 1960-1980. Res. Br. Can. Agric. Publ. 1813, 1986.

Miscanthus × giganteus is a warm-season perennial grass, native to eastern Asia. Brought into the United States as a landscape plant, it is currently being considered as a potential biomass fuel crop. In August 2009, a newly established and a 2-year-old M. × giganteus field research trial near Lexington, KY were found to have 100% incidence of severe leaf blight. Brown, mosaic-like, coalesced necrotic lesions covered leaf blades and sheaths on every stand, ultimately killing some leaves and tillers. The disease was more destructive in the newly established trial where 4- to 5-month-old M. × giganteus tillers were killed. No fruiting bodies were found immediately on diseased leaves. However, surface-disinfested diseased leaf tissue produced a sooty black mass of conidia after 1 week following incubation in a petri dish moisture chamber at 25°C in the dark. Single conidia isolations were made on half-strength potato dextrose agar (HSPDA) amended with 25 mg/liter of rifamycin and incubated at 25°C. Morphological characteristics of the fungus fit those originally described for Pithomyces chartarum (Berk. & Curt.) M.B. Ellis (2). Colonies were fast growing on HSPDA, at first hyaline, then shortly punctiform, grayish black, up to 1-mm diameter, and then became confluent, producing several dark brown multicellular conidia on small peg-like denticles on branched conidiophores. Every detached conidium had a small piece of the denticle attached to its base. The conidia were echinulate, broadly ellipsoidal, pyriform, 18 to 29 × 11 to 18 μm, with three transverse septa, and a longitudinal septum constricted at the transverse septa. The identity of the fungus was confirmed by sequence analysis of the internal transcribed spacers (ITS) region of the nuclear ribosomal DNA. The 615-bp cloned and sequenced amplicon (Accession No. GU195649) was 99% identical to sequences from multiple isolates of Leptosphaerulina chartarum (anamorph Pithomyces chartarum) in the GenBank. Five potted M. × giganteus plants (45 days old) were spray inoculated with an aqueous conidial suspension (2 × 106 conidia/ml) and incubated in one tier of a two-tiered-growth chamber at 86 to 90% relative humidity. Initial incubation was in the dark at 26°C for 48 h, and thereafter at alternating 15 h of light (320 μmol) at 25°C and 9 h of darkness at 23°C. Control plants were sprayed with sterile water and incubated in the second tier of the same growth chamber. A week after inoculation, leaf blight developed on all inoculated plants, but not the controls. P. chartarum was reisolated from infected leaves 2 weeks after inoculation. To our knowledge, this is the first report of P. chartarum causing a disease on Miscanthus (3). The fungus is cosmopolitan, usually saprophytic, but can cause diseases on a wide range of plants as well as produce mycotoxins (3). It has been reported to cause a leaf spot of smooth bromegrass (Bromus inermis) in Nebraska (1) and a leaf blight of wheat (Triticum aestivum) in Hungary (4). The observed disease severity suggests P. chartarum could potentially limit M. × giganteus production as an ethanol feedstock. References: (1) C. Eken et al. Plant Dis. 90:108, 2006. (2) M. B. Ellis. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute, Kew, Surrey, England, 1971. (3) D. F. Farr et al. Fungal Databases, Systematic Mycology and Microbiology Laboratory. Online publication. ARS, USDA, 2010. (4) B. Tóth et al. J. Plant Pathol. 89:405, 2007.

There are few reports on diseases of switchgrass. In November 2009, light brown to white bleached spots (1 to 2 × 3 to 4 μm) were observed on ‘Alamo’ switchgrass (Panicum virgatum L.) grown in a growth chamber in Knoxville, TN, from surface-disinfested seed produced in Colorado. Symptomatic leaf tissue was surface sterilized, air dried, and plated on 2% water agar (WA) amended with 6.9 mg fenpropathrin/liter (Danitol 2.4 EC, Valent Chemical, Walnut Creek, CA) and 10 mg/liter rifampicin (Sigma-Aldrich, St. Louis, MO). Plates were incubated at 26°C in the dark for 5 days. A sporulating, dematiaceous, mitosporic fungus was observed and transferred to potato dextrose agar. Colonies were white to gray, with brown as conidia increased. Conidia ranged in size from 10 to 22.5 × 20 to 37.5 (average 15.2 × 26.5) μm. Conidia were golden to dark brown, broadly ellipsoidal, some pyriform, with one longitudinal septum and two to three transverse septa, sometimes constricted at the transverse septa. Based on microscopic examination, the fungus was identified as Pithomyces chartarum (Berk. & Curt.) M.B. Ellis (1); observations were consistent with the authority (2). Pathogenicity assays were conducted with 5-week-old ‘Alamo’ switchgrass grown from seed scarified with 60% sulfuric acid and surface-sterilized with 50% bleach. Seed were sown in 9 × 9-cm pots containing 50% (v/v) ProMix Potting and Seeding Mix (Premier Tech Horticulture, Québec, Canada) and 50% Turface ProLeague (Profile Products, Buffalo Grove, IL). Eight replicate pots with ~20 plants each were sprayed with a spore suspension of 5.7 × 105 spores/ml sterile water prepared from 6-day-old cultures grown on V8 juice agar in the dark. Two more pots were sprayed with sterile water to serve as controls. All plants were subjected to high humidity for 72 h by enclosure in a plastic bag. Plants were placed in a growth chamber at 25/20°C with a 12-h photoperiod. Leaf spot symptoms similar to the original disease were evident on plants in each of the eight replicate pots 6 to 10 days post-inoculation. Control plants had no symptoms. Lesions were excised from leaves, surface sterilized, and plated on WA. The resulting cultures were again identified as P. chartarum based on morphology. The internal transcribed spacer (ITS) region of rDNA from the original isolate and the pathogen recovered from plants in the pathogenicity tests were amplified with PCR using primers ITS4 and ITS5. PCR amplicons were obtained from both isolates, sequenced, and found to have 100% identity. A 580-bp sequence was deposited at GenBank (Accession No. JQ406588). The nucleotide sequence had 98 to 100% identity to the ITS sequences of isolates of Leptosphaerulina chartarum (anamorph: P. chartarum), including isolate Mxg-KY09-s4 (GU195649) from leaf spot on Miscanthus × giganteus in Kentucky (1), and isolates from leaf lesions on wheat (EF489400 and JX442978). To our knowledge, leaf spot caused by P. chartarum has not been described on switchgrass (3). Pithomyces chartarum is a seedborne pathogen of switchgrass, and may play a role in stand establishment. References: (1) M. O. Ahonsi et al. Plant Dis. 94:480, 2010. (2) M. B. Ellis. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute, Kew, Surrey, England. 1971. (3) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA, Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , 18 January 2013.

Fotossensibilização refere-se ao aumento da resposta à radiação ultravioleta da luz solar, causada por um agente fotodinâmico na pele. A sensibilidade à fotossensibilização de 80 cordeiros mestiços desmamados e manejados em lotação rotativa, durante 120 dias, foi avaliada em pastagem de Brachiaria brizantha cv. Marandu. Os cordeiros foram suplementados a 1% do seu peso corporal com os tratamentos, a saber: A - suplemento basal com 12% PB; B - suplemento com 18% de PB; C - suplemento com 18% de PB + propionato de Zn e D - suplemento com 18% de PB + cloreto de colina protegida. Ao término do experimento os animais foram abatidos. Os objetivos foram: avaliar o efeito da adaptação dos animais suplementados às condições de manejo em Brachiaria brizantha e a toxidez da planta aos cordeiros; caracterizar as causas da fotossensibilização; viabilizar o possível controle da verminose associada ao manejo de cordeiros em lotação rotativa e à suplementação mineral e proteica, com ou sem adição de aditivos; relacionar os teores de saponina e a presença de esporos de Pithomyces chartarum em amostras da forragem à ocorrência de casos de fotossensibilização hepatógena. O delineamento experimental foi em blocos completos e casualizados, com quatro tratamentos e quatro repetições, num total de 5 animais por tratamento. Realizou-se a análise da variância para as variáveis e as médias foram comparadas pelo teste t-Student ao nível de significância de 5%. Foram observadas baixas contagens de esporos de Pithomyces chartarum (0 - 15.000 esporos) na parte senescente da planta. A concentração de saponina protodioscina variou de 0,52 a 0,65%. Do 8º ao 58º dia ocorreram 20% de mortalidade dos animais. A avaliação histopatológica, do fígado dos animais que vieram a óbito, foi compatível com as lesões causadas pela saponina. Os padrões histológicos das lesões hepáticas encontradas nos animais, ao final do experimento, não diferiram entre os tratamentos, bem como para as análises bioquímicas: colesterol, triglicerídeos, bilirrubinas, proteína total, albumina, creatinina, ureia, AST, GGT. Ocorreram diferenças nas concentrações séricas de bilirrubinas, proteínas, albumina, AST, GGT, ureia, creatinina, colesterol, triglicerídeos, entre cordeiros sobreviventes e os que morreram. O método rotativo foi efetivo no controle da verminose, ficando a contagem de ovos por grama de fezes (OPG) abaixo de 500 ao final do experimento, não ocorrendo diferença entre os suplementos proteicos e entre os aditivos utilizados. Não houve efeito no desempenho dos cordeiros, que chegaram ao final do experimento, pela inclusão de suplementos proteicos e de aditivos.
Photosensitization refers to increase in response to ultraviolet radiation from sunlight, caused by a photodynamic agent into the skin. The sensitivity of the photosensitization at 80 crossbred lambs weaned was evaluated on Brachiaria brizantha cv. Marandu managed in rotational grazing for 120 days. Lambs were supplemented to 1% of their body weight with different treatments: A - basal supplement with 12% CP; B - supplement with 18% CP; C - supplement with18% CP + zinc proprionate and D - supplement with18 % of CP + protected choline chloride. At the end of the experiment the animals were slaughtered. The objectives were to evaluate the effect of adaptation of animals supplemented to handling Brachiaria brizantha and toxicity of the plant to lambs weaned; to characterize the causes of photosensitivity, the possible control of parasitism associated with the management of sheep grazing on rotational grazing, mineral supplementation and protein with or without the addition of additives; to relate the levels of saponin and the presence of spores Pithomyces chartarum in samples of forage and the occurrence of hepatic photosensitization. The experimental design was a complete randomized block design and assigned to four treatments and four replications for a total of five animals per treatment. The analysis of variance was performed and the means test t-Student a significance level of 5% for the effect of each treatment was used. Low count of Pithomyces chartarum spores (spores 0-15,000) in the senescent part of the plant was observed. The concentration of saponin protodioscine ranged from 0.52 to 0.65 %. Occurred between the 8º and 58º day mortality of 20 % of the animals. Histopathology of the liver of animals that died during the experiment was consistent with lesions determined by saponin. The histological patterns of liver lesions found in animals at the end of the experiment did not differ between treatments, as well as, for biochemical analysis: cholesterol, triglycerides, bilirubin, total protein, albumin, creatinine, urea, AST and GGT. There were differences in serum bilirubin, protein, albumin, AST, GGT, urea, creatinine, cholesterol and triglycerides between survivors and that died. The rotational grazing system was effective in the control of nematode parasites getting below 500 EPG at the end of the experiment, there was no difference between the protein concentrations, nor for the additives used. The additives zinc oxide and choline chloride did not improve the performance of sheep.

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Numerous outbreaks of photosensitization in herbivorous animals maintained on Brachiaria pastures occur in Brazil, and the economic losses caused are of great concern due to the large areas in the country planted with this grass. The vast majority of outbreaks has been attributed to the sporidesmin containing spores of Pithomyces chartarum, a fungus which occurs in many countries of temperate climate. However, there are differences between the liver lesions in animals that develop photosensitization on pastures of Brachiaria spp and the ones described in P. chartarum poisoning. In several outbreaks reported from Brazil, no evidence for toxicity of the spores was revealed. As the isolation of toxic saponins from Brachiaria grasses has been reported in the literature, the real cause of the photosensitization in Brazil needs to be clarified, in order to be able to adopt correct preventive measures to avoid the condition. The main objective of this study was to show the different epidemiological, clinical, pathological and toxicological aspects of the two poisonings, based on data from the literature and our own observations of pithomycotoxicosis in Portugal and on the data of the photosensitization which occurs on Brachiaria pastures in Brazil. We concluded that the saponin content of the grass is be responsible for the outbreaks of photosensitizing disease which occur annually on Brazilian pastures.
Numerosos surtos de fotossensibiliza??o em animais mantidos em pastos de Brachiaria spp v?m ocorrendo no Brasil e as perdas econ?micas resultantes t?m sido foco de preocupa??o, em especial devido ?s grandes ?reas cultivadas dessa gram?nea no pa?s. A maioria dessas ocorr?ncias vem sendo atribu?das ? esporidesmina, presente em esporos do fungo Pithomyces chartarum, que ocorre em muitos pa?ses de clima temperado. No entanto, h? diferen?as entre o aspecto an?tomo-histopatol?gico verificado no f?gado de animais que desenvolvem fotossensibiliza??o em pastos de Brachiaria spp e o descrito na intoxica??o por P. chartarum. Nos diversos surtos relatados no Brasil n?o se conseguiu demonstrar a toxidez dos esporos. Como o isolamento de saponinas t?xicas tem sido reportado em pastagens de Brachiaria, a causa dos surtos de fotossensibiliza??o no Brasil precisa ser esclarecida, para que corretas medidas preventivas sejam adotadas e, a doen?a evitada. Este trabalho tem por objetivo principal demonstrar, atrav?s das diferen?as epidemiol?gicas, cl?nico-patol?gicas e toxicol?gicas peculiares ?s duas condi??es, colhidas na literatura e confrontadas com nossas pr?prias observa??es sobre pitomicotoxicose em Portugal e intoxica??o pela Brachiaria sp no Brasil, que as saponinas contidas na Brachiaria sp s?o respons?veis pelos surtos de fotossensibiliza??o que ocorrem anualmente nas pastagens brasileiras.

Facial eczema disease (FE) is a secondary photosensitisation disease of ruminants caused by exposure to the mycotoxin sporidesmin. Resistance to FE has a significant genetic component and previous research has included a whole genome scan and investigation of candidate genes. The aim of this study was to use multiple approaches to identify genes associated with resistance to FE. ABC transporters have been considered as putative candidate genes for FE since the yeast ABC transporter, PDR5, was found to modulate sensitivity to sporidesmin in Saccharomyces cerevisiae. A previous study had shown that hepatic expression of the ovine ABC transporter, ABCB1, was induced following exposure to sporidesmin but only in resistant animals (Longley (1998) PhD Thesis, University of Otago). In the present study, using qRT-PCR, a difference in the expression of ABCB1 between resistant and susceptible animals was not confirmed. It is concluded that ABCB1 is not likely to be a candidate gene for FE. As the full genome sequences for several mammalian species are now available, phylogenetic analyses were used to identify the most likely mammalian ortholog of the yeast PDR5 protein. This analysis found that the yeast PDR5 protein was most closely related to the mammalian ABCG sub-family. The human ABCG sub-family has five members one of which, ABCG2, is a known xenobiotic transporter. Comparative mapping of ABCG2 indicated that it co-localised to a region of the sheep genome weakly associated with resistance to FE. The full-length sequence of ovine ABCG2 was determined and two synonymous polymorphisms were found. These two polymorphisms, together with an intronic SNP were genotyped across a panel of selection-line animals. The allele frequencies of the intronic SNP were found to be significantly different between the selection lines, providing evidence for the association of ABCG2 with resistance to FE. The hepatic expression of ABCG2 was examined but no differential expression between the selection-lines was observed. Global gene expression profiling via microarray analysis was undertaken as a novel approach to identify candidate genes. Differences in gene expression were examined between naïve and sporidesmin-dosed resistant and susceptible animals using a bovine cDNA microarray. A small number of differentially expressed genes were identified. Follow-up studies found that there were a relatively high number of errors in EST identity. Eight differentially expressed genes were selected for confirmation by Northern analysis. Six of these genes were shown to be differentially expressed, but neither the patterns nor the magnitude of the differential expression reflected that observed on the microarray. One of the six genes identified as differentially expressed was catalase, which has previously been implicated in resistance to FE. This finding validates the approach taken using gene expression profiling to identify candidate genes. The final approach used in this study necessitated the development and characterisation of an in vitro system for studying sporidesmin toxicity. The system chosen was a human hepatoma cell line, HepG2. To date the only effective treatment for FE is the prophylactic administration of high levels of zinc sulphate. The mechanism of protection by zinc is unknown, but zinc is known to be a potent modulator of gene expression. Conceptually, any genes modulated by zinc are possible candidates for resistance to FE. It was shown that zinc pre-treatment could protect HepG2 cells against sporidesmin-induced cytotoxicity. Equivalent protection was provided by the addition of zinc in the presence of the transcriptional inhibitor actinomycin D, suggesting that the mechanism of zinc protection is independent of de novo gene transcription. Overall, the goal of this project was to find genes to assist selection of sheep resistant to FE. Toward this goal, this research has identified several new candidate genes and avenues for investigation.