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Fungal Colonization (fungal + colonization)
Selected AbstractsSeasonal and substrate preferences of fungi colonizing leaves in streams: traditional versus molecular evidenceENVIRONMENTAL MICROBIOLOGY, Issue 2 2005Liliya G. Nikolcheva Summary Aquatic hyphomycetes are the main fungal decomposers of plant litter in streams. We compared the importance of substrate (three leaf species, wood) and season on fungal colonization. Substrates were exposed for 12 4-week periods. After recovery, mass loss, fungal biomass and release of conidia by aquatic hyphomycetes were measured. Fungal communities were characterized by counting and identifying released conidia and by extracting and amplifying fungal DNA (ITS2), which was subdivided into phylotypes by denaturing gradient gel electrophoresis (DGGE) and terminal-restriction fragment length polymorphism (T-RFLP). Mass loss, fungal biomass and reproduction were positively correlated with stream temperature. Conidial diversity was highest between May and September. Numbers of different phylotypes were more stable. Principal coordinate analyses (PCO) and canonical analyses of principal coordinates (CAP) of presence/absence data (DGGE bands, T-RFLP peaks and conidial species) showed a clear seasonal trend (P, 0.002) but no substrate effect (P, 0.88). Season was also a significant factor when proportional similarities of conidial communities or relative intensities of DGGE bands were evaluated (P, 0.003). Substrate was a significant factor determining DGGE band intensities (P = 0.002), but did not significantly affect conidial communities (P = 0.50). Both traditional and molecular techniques suggest that strict exclusion of fungi by substrate type is rare, and that presence of different species or phylotypes is governed by season. Biomasses of the various taxa (based on DGGE band intensities) were related to substrate type. [source] Fungi isolated from Picea abies infested by the bark beetle Ips typographus in the Bia,owie,a forest in north-eastern PolandFOREST PATHOLOGY, Issue 2 2010T. Kirisits Summary The assemblage of fungi occurring in the sapwood of Norway spruce (Picea abies) and in bark beetle galleries following attack by the Eurasian spruce bark beetle Ips typographus was investigated in the Bia,owie,a forest in north-eastern Poland. Fungi were isolated from blue-stained sapwood of beetle-infested spruce trees in June 2002, and a few isolates were also obtained from ascospores and conidia taken from perithecia and asexual structures occurring in the gallery systems of the insects. The mycobiota of I. typographus in the Bia,owie,a forest was dominated by ophiostomatoid fungi, which were represented by seven species. Four species, including Ceratocystis polonica, Grosmannia penicillata, Ophiostoma ainoae and Ophiostoma bicolor were isolated at high frequencies, whereas three other taxa, Ceratocystiopsis minuta, Ceratocystiopsis alba and a Pesotum sp. were rare. The anamorphic fungus Graphium fimbriisporum and yeasts also occurred occasionally. In addition, the basidiomycete Gloeocystidium ipidophilum was relatively common. The pathogenic blue-stain fungus C. polonica was the dominant fungal associate of I. typographus in the Bia,owie,a forest, which is consistent with a previous study at this area in the 1930s. Ceratocystis polonica was the most frequently isolated species at the leading edge of fungal colonization in the sapwood and had on an average penetrated deeper into the wood than other fungal associates. This suggests that it acts as a primary invader into the sapwood after attack by I. typographus in the Bia,owie,a forest, followed by O. bicolor, O. ainoae, G. ipidophilum and G. penicillata. Thus far, the Bia,owie,a forest is one of the few areas in Europe, where C. polonica has been reported as a dominate fungal associate of I. typographus. [source] In vitro characterization of Inocutis jamaicensis and experimental inoculation of Eucalyptus globulus standing treesFOREST PATHOLOGY, Issue 5 2009S. Lupo Summary Lesions of variable size, associated with the hymenomycete Inocutis jamaicensis, a white-rot fungus, have been observed on the stems of Eucalyptus globulus trees in Uruguay. The aim of this study was to evaluate some ecophysiological characteristics of I. jamaicensis and assess its ability to colonize E. globulus trees of two different seed origins (Geeveston and Jeeralang) and the clone, 334-1-AR, obtained by micropropagation (ENCE, Spain). The growth of an I. jamaicensis isolate (MVHC11379) was evaluated at 25°C in a medium with a water potential of 0 (, = 0). The growth rate did not vary significantly with a growth medium pH of between 4 and 7. I. jamaicensis showed no growth at either 5 or 37°C at any pH or , tested. Weight loss of heartwood and sapwood of different plant provenances inoculated with I. jamaicensis under laboratory conditions was evaluated, and significant differences observed. Lignin-modifying enzyme activity was evaluated in culture medium with or without E. globulus sawdust as substrate or inducer. Laccase activity was observed with sawdust and manganese peroxidase activity with and without sawdust. Only slight activity of aryl-alcohol oxidase and lignin peroxidase was detected without sawdust. Experimental inoculation with I. jamaicensis of 3-year-old Geeveston and Jeeralang, and of 4-year-old 334-1-AR stems, resulted in successful fungal colonization of 56% of the 334-1-AR, 50% of Geeveston and 25% of Jeeralang trees. Only the heartwood was decayed. In 334-1-AR, the rotted wood was delimited by a reaction zone. Wood characteristics and the ability of I. jamaicensis to overcome the chemical reactions in the tree could partially explain differences in susceptibility to the fungus among provenances observed under natural and laboratory conditions. [source] Induced resistance of Norway spruce, variation of phenolic compounds and their effects on fungal pathogensFOREST PATHOLOGY, Issue 2 2000P. C. Evensen Summary Three clones of Norway spruce (Picea abies) were studied for their response to mass-inoculation with the blue-stain fungus Ceratocystis polonica. The effect of different pretreatments (fungal inoculation and wounding) before mass-inoculation was investigated for their possible role in an acquired resistance reaction. Pretreated trees showed enhanced resistance to the subsequent mass-inoculation relative to control trees that received no pretreatment. Furthermore, the fungal colonization of inoculated trees was less than that of wounded trees. The phenolic content of the bark, analysed by RP-HPLC, was compared in trees receiving different treatments. Trees inoculated with C. polonica had higher average concentration of (+)-catechin, taxifolin and trans-resveratrol than wounded trees. Both inoculated and wounded trees had higher average concentrations of these compounds than control trees. The effect of the phenolic extract of Norway spruce bark on the growth of the root rot fungus Heterobasidion annosum and the blue-stain fungi C. polonica and Ophiostoma penicillatum were investigated in vitro. Heterobasidion annosum was not negatively affected, and the extracts had fungistatic effects on the blue-stain fungi. The growth of O. penicillatum was more inhibited than the growth of the more aggressive C. polonica. [source] Trends in fungal colonization of pancreatic necrosis in patients undergoing necrosectomy for acute pancreatitisHPB, Issue 2 2005N. K. K. KING Abstract Background. This study examines fungal colonization of post-inflammatory pancreatic necrosis in a cohort of patients undergoing open surgical necrosectomy in a single, tertiary referral unit over a 10-year period. Methods. The charts of all patients with acute pancreatitis who underwent surgical necrosectomy during the period January 1992 to December 2001 were examined. Following exclusions a population of 30 patients were identified. There were 18 men with a median (range) age of 42 (20,69) years. Sixteen (53%) underwent surgery because of positive fine needle aspirates and the remainder underwent surgery on clinical grounds. Twenty-nine (97%) received antibiotics prior to necrosectomy. Principal outcomes were the results of microbiological culture with reference to isolation of fungi, site of isolates, trends in colonization and outcome. Results. Candida were cultured from pancreatic necrosis in 5 (17%). These 5 individuals also had positive candidal cultures from sputum or bronchial aspirates. There were no deaths in patients with fungal colonization of necrosis. There was no change in the annual incidence of fungal colonization of necrosis over the study period. Conclusion. Although this is a small study, there are two consistent observations: mortality in fungal colonization of necrosis was low and there was no change in the annual incidence of fungal colonization of necrosis over the decade. Discrepancies between these findings and those of previous reports mandate larger prospective evaluation. [source] Frost Injury as a Possible Inciting Factor in Bud and Shoot Necroses of Fraxinus excelsior L.JOURNAL OF PHYTOPATHOLOGY, Issue 9 2005P. M. Pukacki Abstract Large numbers of European ash have died in Poland in all age classes during the last ten years. The characteristic symptom occurring on shoots of planted and self-sown seedlings was bark necroses starting from the shoot apex, necrotic buds, or leaf and twig scars. The results showed that in the bud tissue of cold acclimated European ash extracellular and intracellular ice formation occurred at approximately ,9 and ,32°C, respectively. In deacclimated plants in spring water supercooling is limited by the heterogenous ice nucleation temperature and consequently the cold tolerance is ,9 to ,4°C for bud tissues and ,13 to ,9°C for shoots. Isolations of fungi were performed from dead buds and from necroses occurring on the main stem. Alternaria alternata, Fusarium lateritium and Phomopsis scobina were among the fungi occurring in both these organs at frequencies of more than 7%. Cylindrocarpon heteronemum, Diplodia mutila and Tubercularia vulgaris from necroses were only isolated in frequencies; 3.3, 1.2 and 5.4%, respectively. It seems likely that freezing injury is the inciting factor, which combined with fungal colonization manifests itself as fatal damage to European ash buds and shoots. [source] An enzyme-linked immunosorbent assay for monitoring of Aspergillus ochraceus growth in coffee powder, chilli powder and poultry feedLETTERS IN APPLIED MICROBIOLOGY, Issue 1 2006S. Anand Abstract Aims:, The work was carried out to develop an immunoassay for estimation of Aspergillus ochraceus biomass on solid substrate. Methods and Results:, An indirect noncompetitive enzyme-linked immunosorbent assay (ELISA) was developed for determination of fungal biomass in food commodities using antibody raised against A. ochraceus mycelial antigen. The sensitivity of the assay was linear in the range of 10,160 ,g fungal biomass per millilitre extract of coffee (R2 = 0·989), poultry feed (R2 = 0·987) and chilli (R2 = 0·989). The growth of A. ochraceus in the food commodities like chilli, coffee beans and poultry feed, under the influence of two levels of moisture (20% and 30%) were monitored by the ELISA. The maximum fungal colonization was observed in poultry feed (9·8 and 11·8 mg g,1) followed by coffee beans (6·8 and 11·3 mg g,1) and chilli (5·1 and 6·3 mg g,1) at 20% and 30% moisture after 20 days of incubation. Similarly the fungus produced maximum ochratoxin A in poultry feed (25 and 120 ,g g,1) followed by coffee beans (8 and 24 ,g g,1) and chilli (0·2 and 0·45 ,g g,1) at 20% and 30% moisture after 20 days of incubation. Conclusions:, The method can be used for quantitative estimation of fungal biomass and comparison of fungal colonization in food substrates varying in composition. Significance and Impact of the Study:, The method can be adapted for studying the fungal colonization in different solid substrates under different culture condition. The method is sensitive to mould colonization of ,0·02% (w/w) and can be used for early detection of specific fungal infestation in food commodities. [source] Layers of defense responses to Leptosphaeria maculans below the RLM1 - and camalexin-dependent resistancesNEW PHYTOLOGIST, Issue 2 2009Mattias Persson Summary ,,Plants have evolved different defense components to counteract pathogen attacks. The resistance locus resistance to Leptosphaeria maculans 1 (RLM1) is a key factor for Arabidopsis thaliana resistance to L. maculans. The present work aimed to reveal downstream defense responses regulated by RLM1. ,,Quantitative assessment of fungal colonization in the host was carried out using quantitative polymerase chain reaction (qPCR) and GUS expression analyses, to further characterize RLM1 resistance and the role of salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) in disease development. Additional assessments of A. thaliana mutants were performed to expand our understanding of this pathosystem. ,,Resistance responses such as lignification and the formation of vascular plugs were found to occur in an RLM1 -dependent manner, in contrast to the RLM1 -independent increase in reactive oxygen species at the stomata and hydathodes. Analyses of mutants defective in hormone signaling in the camalexin-free rlm1Lerpad3 background revealed a significant influence of JA and ET on symptom development and pathogen colonization. ,,The overall results indicate that the defense responses of primary importance induced by RLM1 are all associated with physical barriers, and that responses of secondary importance involve complex cross-talk among SA, JA and ET. Our observations further suggest that ET positively affects fungal colonization. [source] Calluna vulgaris root cells show increased capacity for amino acid uptake when colonized with the mycorrhizal fungus Hymenoscyphus ericaeNEW PHYTOLOGIST, Issue 3 2002Sergei G. Sokolovski Summary ,,Ericoid mycorrhizas are believed to improve N nutrition of many ericaceous plant species that typically occur in habitats with impoverished nutrient status, by releasing amino acids from organic N forms. Despite the ubiquity of mycorrhizal formation the mechanisms and regulation of nutrient transport in mycorrhizal associations are poorly understood. ,,We used an electrophysiological approach to study how amino acid transport characteristics of Calluna vulgaris were affected by colonization with the ericoid mycorrhiza fungus Hymenoscyphus ericae . ,,Both the Vmax and Km parameters of amino acid uptake were affected by fungal colonization in a manner consistent with an increased availability of amino acid to the plant. ,,The ecophysiological significance of altered amino acid transport in colonized root cells of C. vulgaris is discussed. [source] Spatial differences in acquisition of soil phosphate between two arbuscular mycorrhizal fungi in symbiosis with Medicago truncatulaNEW PHYTOLOGIST, Issue 2 2000F. A. SMITH Responses of Medicago truncatula to colonization by two arbuscular mycorrhizal fungi, Scutellospora calospora isolate WUM 12(2) and Glomus caledonium isolate RIS 42, were compared in the light of previous findings that the former fungus can be ineffective as a beneficial microsymbiont with some host plants. The plants were grown individually in two-compartment systems in which a lateral side arm containing soil labelled with 33P was separated from the main soil compartment by a nylon mesh that prevented penetration by roots but not fungal hyphae. Fungal inoculum was applied as a root,soil mixture in a band opposite the side arm. Nonmycorrhizal controls were set up similarly, without inoculum. There were harvests at 28, 35, 42 and 49 d. Both sets of mycorrhizal plants grew better than nonmycorrhizal plants and initially had higher concentrations of P in shoots and roots. Plants grown with S. calospora grew better than plants grown with G. caledonium, and this was associated with somewhat greater fungal colonization in terms of intraradical hyphae and numbers of arbuscules. Scutellospora calospora formed denser hyphae at root surfaces than G. caledonium. By 28 d there were extensive hyphae of both fungi in the side arms, and after 35 d S. calospora produced denser hyphae there than G. caledonium. Nevertheless, there was very little transfer of 33P via S. calospora to the plant at 28 d, and thereafter its transfer increased at a rate only c. 33% of that via G. caledonium. The results showed that plants colonized by S. calospora preferentially obtained P from sites in the main soil chamber relatively close to the roots, compared with plants colonized by G. caledonium. Hence formation of a highly beneficial arbuscular mycorrhizal symbiosis does not necessarily depend on development of hyphae at a distance from the roots or on large-scale translocation of P from distant sites. The results are discussed in relation to previous studies with compartmented systems that have involved the same fungi. Possible causes of the variable effects of S. calospora in symbiosis with different host plants are briefly assessed. Differences in spatial abilities of individual arbuscular mycorrhizal fungi to acquire P might have strong ecological implications for plant growth in soils low in P. [source] Post-harvest fungal quality of selected chewing sticksORAL DISEASES, Issue 2 2003E Etebu OBJECTIVE:, To study post-harvest fungal overgrowth on chewing sticks used for oral hygiene measures and role of disinfection. METHODS: ,The post-harvest fungal spoilage of chewing sticks ( Garcinia kola , Glyphea brevis and Azadirachta indica ) was investigated by subjecting the chewing sticks to different preparatory methods (some disinfected in 0.7% sodium hypochlorite before storage), storage conditions (unsealed or sealed in clear polythene) and different storage periods (2, 3 and 4 weeks). RESULTS: ,Significant differences ( P = 0.05) in mean percentage fungal colonization were dependent on plant type and storage period, but not on preparative methods and storage conditions. There were, however, significant interactions between chewing sticks and preparative methods, storage conditions and storage periods, respectively. Azadirachta indica was observed to be more susceptible to post-harvest spoilage organisms than other test plants. Generally, percentage fungal colonization increased with increase in storage period. Four genera, Penicillium spp., Aspergillus spp., Mucor spp. and Botryodiplodia spp., were implicated with post-harvest colonization of chewing sticks after 4 weeks of storage. CONCLUSION: ,The use of harvested chewing sticks after prolonged storage period is therefore not advisable for oral hygiene measures. [source] Maize mutants affected at distinct stages of the arbuscular mycorrhizal symbiosisTHE PLANT JOURNAL, Issue 2 2006Uta Paszkowski Summary Maize mutants affected in the symbiotic interaction with the arbuscular mycorrhizal fungus Glomus mosseae have been found by a visual, macroscopic screen in a Mutator -tagged population of maize. Seven mutants have been identified, falling into three phenotypic classes. For each class one mutant has been characterized in more detail. The nope1 (noperception 1) mutant does not support appressoria formation of G. mosseae, suggesting the absence of a plant-encoded function necessary for early recognition prior to contact. The phenotype segregated as a monogenic recessive trait, indicating that a mutation in a single locus abolished compatibility of maize to G. mosseae. On a second mutant termed taci1 (taciturn 1), appressoria form at reduced frequency but their morphology is normal and leads to penetration of the rhizodermis. However, intraradically, the majority of hyphae are septate, resulting in terminated fungal spreading. This phenotype suggests that the mutation of taci1 has an effect on recognition and on cortex invasion. Segregation analysis indicates taci1 to carry a recessive mutation. In contrast, wild-type fungal morphology has been recorded in the Pram1 (Precocious arbuscular mycorrhiza 1) mutant, which displays enhanced and earlier fungal invasion. This trait segregates in a dominant fashion indicative of a gain-of-function mutation affecting the plant's control over restricting fungal colonization. [source] The characterization of novel mycorrhiza-specific phosphate transporters from Lycopersicon esculentum and Solanum tuberosum uncovers functional redundancy in symbiotic phosphate transport in solanaceous speciesTHE PLANT JOURNAL, Issue 2 2005Réka Nagy Summary Solanaceous species are among the >200 000 plant species worldwide forming a mycorrhiza, that is, a root living in symbiosis with soil-borne arbuscular-mycorrhizal (AM) fungi. An important parameter of this symbiosis, which is vital for ecosystem productivity, agriculture, and horticulture, is the transfer of phosphate (Pi) from the AM fungus to the plant, facilitated by plasma membrane-spanning Pi transporter proteins. The first mycorrhiza-specific plant Pi transporter to be identified, was StPT3 from potato [Nature414 (2004) 462]. Here, we describe novel Pi transporters from the solanaceous species tomato, LePT4, and its orthologue StPT4 from potato, both being members of the Pht1 family of plant Pi transporters. Phylogenetic tree analysis demonstrates clustering of both LePT4 and StPT4 with the mycorrhiza-specific Pi transporter from Medicago truncatula [Plant Cell, 14 (2002) 2413] and rice [Proc. Natl Acad. Sci. USA, 99 (2002) 13324], respectively, but not with StPT3, indicating that two non-orthologous mycorrhiza-responsive genes encoding Pi transporters are co-expressed in the Solanaceae. The cloned promoter regions from both genes, LePT4 and StPT4, exhibit a high degree of sequence identity and were shown to direct expression exclusively in colonized cells when fused to the GUS reporter gene, in accordance with the abundance of LePT4 and StPT4 transcripts in mycorrhized roots. Furthermore, extensive sequencing of StPT4 -like clones and subsequent expression analysis in potato and tomato revealed the presence of a close paralogue of StPT4 and LePT4, named StPT5 and LePT5, respectively, representing a third Pi transport system in solanaceous species which is upregulated upon AM fungal colonization of roots. Knock out of LePT4 in the tomato cv. MicroTom indicated considerable redundancy between LePT4 and other Pi transporters in tomato. [source] Treatment of Candida infection in patients with infected pancreatic necrosisBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 7 2000G. Farkas Background The purpose of this review was to determine the incidence of Candida infection in patients with infected pancreatic necrosis, to determine the most frequent risk factors and to assess the best treatment approach for disseminated candidal infections. Methods Of 145 patients with infected pancreatic necrosis identified, 30 (21 per cent) were infected with C. albicans. Risk factors identified in patients with Candida infection included the presence of necrotic tissue, and the use of broad-spectrum antibiotics, intravascular catheters and parenteral nutrition. Results With one exception, all cases involved mixed bacterial and fungal infections. The positive fungal result was obtained either during or after operation. Sixteen of the 30 patients displayed fungal colonization, while the other 14 had disseminated fungal infection. There were two deaths in the disseminated group, but none in the colonization group. In both fatal cases, flucytosine was applied. When fluconazole was used against disseminated fungal infection, no death was noted. Recently, prophylactic fluconazole has also been used in 20 patients with infected pancreatic necrosis, with no evidence of fungal infection after operation. Conclusion The combination of adequate surgical treatment with effective antibiotics and early antifungal therapy is the ideal management approach for infected pancreatic necrosis with Candida infection. Fluconazole may be regarded as an efficient drug for the prophylaxis of candidiasis. © 2000 British Journal of Surgery Society Ltd [source] | |||||||||||||||||||||||||