| cerato-ulmin, a hydrophobin secreted by the causal agents of dutch elm disease, is a parasitic fitness factor. | dutch elm disease is caused by the aggressive ophiostoma novo-ulmi and the nonaggressive o. ulmi. both secrete the protein cerato-ulmin (cu). to determine what role cu plays in the pathology of dutch elm disease, we constructed a cu overexpression mutant of the nonaggressive o. ulmi h5. stable integration of a single copy of the cu gene from the aggressive o. novo-ulmi into the genome of the nonaggressive isolate resulted in increased secretion of cu protein. trials with american elm, ulmus amer ... | 1997 | 9344630 |
| novel structures of two virus-like rna elements from a diseased isolate of the dutch elm disease fungus, ophiostoma novo-ulmi. | the nucleotide sequences of 2 of the 10 mitochondrial double-stranded (ds) rna segments in a diseased isolate, log 1/3-8d2 (ld), of ophiostoma novo-ulmi, rna-7 (1057 nucleotides) and rna-10 (317-330 nucleotides), have been determined. both rnas are a-u-rich, but in southern and northern blots, no hybridization with mitochondrial dna or rna could be detected. only very short open reading frames were found in both rnas. as most of its sequence is unrelated to any of the other ld dsrnas, rna-7 may ... | 1998 | 9501045 |
| evolutionary relationships among putative rna-dependent rna polymerases encoded by a mitochondrial virus-like rna in the dutch elm disease fungus, ophiostoma novo-ulmi, by other viruses and virus-like rnas and by the arabidopsis mitochondrial genome. | the nucleotide sequence (2617 nucleotides) of virus-like double-stranded (ds) rna 3a in a diseased isolate, log1/3-8d2 (ld), of the ascomycete fungus ophiostoma novo-ulmi has been determined. one strand of the dsrna contains an open reading frame (orf) with the potential to encode a protein of 718 amino acids, and the complementary strand contains two smaller orfs with the potential to encode proteins of 178 and 182 amino acids, respectively. the large orf contains 12 uga codons which code for t ... | 1998 | 9657003 |
| isolation of adenylate cyclase gene-specific sequences from ophiostoma novo-ulmi, candida albicans, and agaricus bisporus by pcr. | degenerate primers corresponding to consensus sequences in the catalytic domains of known fungal adenylate cyclases were used to isolate gene-specific homologs from the dutch elm disease pathogen ophiostoma novo-ulmi, the dimorphic human pathogen candida albicans, and the commercial mushroom agaricus bisporus. all three fungi gave the expected pcr product of about 390 bp. computer searches of the databases revealed that the products generated from o. novo-ulmi and c. albicans were highly similar ... | 1998 | 9767719 |
| multiple mitochondrial viruses in an isolate of the dutch elm disease fungus ophiostoma novo-ulmi. | the nucleotide sequences of three mitochondrial virus double-stranded (ds) rnas, rna-4 (2599 nucleotides), rna-5 (2474 nucleotides), and rna-6 (2343 nucleotides), in a diseased isolate log1/3-8d2 (ld) of the dutch elm disease fungus ophiostoma novo-ulmi have been determined. all these rnas are a-u-rich (71-73% a + u residues). using the fungal mitochondrial genetic code in which uga codes for tryptophan, the positive-strand of each of rnas 4, 5, and 6 contains a single open reading frame (orf) w ... | 1999 | 10329574 |
| sequence analysis of the chitin synthase a gene of the dutch elm pathogen ophiostoma novo-ulmi indicates a close association with the human pathogen sporothrix schenckii. | degenerate oligonucleotide primers were designed according to conserved regions of the chitin synthase gene family and used to amplify a 621 basepair (bp) fragment from genomic dna of ophiostoma novo-ulmi, the causal agent of dutch elm disease. the amplification product was used as a hybridization probe to screen a library of genomic dna sequences and to retrieve a full-length chitin synthase gene (chsa). the putative coding region of the gene was 2619 bp long, lacked introns, and encoded a poly ... | 1999 | 10524253 |
| detection of an rna-dependent rna polymerase in mitochondria from a mitovirus-infected isolate of the dutch elm disease fungus, ophiostoma novo-ulmi. | rna-dependent rna polymerase (rdrp) activity has been detected in mitochondria from an isolate of ophiostoma novo-ulmi infected with o. novo-ulmi mitovirus 6 (onumv6). the reaction products corresponded to the double-stranded and single-stranded forms of onumv6 rna. western blot analysis using antibodies raised against a conserved rdrp region has detected a protein of ca. 80 kda in onumv6-infected mitochondria, close to the predicted size of the onumv6 rdrp. no rdrp activity or protein was detec ... | 2000 | 10704332 |
| a gene associated with filamentous growth in ophiostoma novo-ulmi has rna-binding motifs and is similar to a yeast gene involved in mrna splicing. | the col1 gene was isolated from ophiostoma novo-ulmi using the techniques of insertional mutagenesis and plasmid rescue. sequence analyses suggest that the col1 gene encodes a unique protein of 826 amino acids with consensus-type rna-binding domains, most similar to a putative protein from schizosaccharomyces pombe which resembles the c-terminus of the saccharomyces cerevisiae u4/u6 splicing factor prp24. disruption of the col1 gene produced the yeast-like col1 mutant. the inability of the mutan ... | 2000 | 10743565 |
| real time rt-pcr quantification and northern analysis of cerato-ulmin ( cu) gene transcription in different strains of the phytopathogens ophiostoma ulmi and o. novo-ulmi. | cerato-ulmin is a surface protein that belongs to the class of fungal proteins known as hydrophobins. this class ii hydrophobin is produced throughout the life cycle and in all developmental stages of ophiostoma novo-ulmi and o. ulmi; the aggressive and non-aggressive pathogens responsible for dutch elm disease. since yeast/mycelial transitions are often important to pathogenesis in dimorphic fungi such as ophiostoma, we have examined the levels and abundance of cu mrna in the yeast and mycelial ... | 2003 | 14513363 |
| cytochemical labeling for fungal and host components in plant tissues inoculated with fungal wilt pathogens. | antibodies to detect pectin in present investigations attached to distinct fibrils in vessel lumina. in carnation infected with an isolate of fusarium oxysporum f.sp., labeling of pathogen cells also occurred; in a resistant cultivar (cv.), it was coincident with proximate pectin fibrils and linked to altered fungal walls, which was the opposite in the susceptible cv., indicating that hindrance of pathogen ability to degrade pectin may be related to resistance. labeling of the fungus in culture ... | 2004 | 15327706 |
| crystallization and preliminary x-ray diffraction studies of a fungal hydrolase from ophiostoma novo-ulmi. | dutch elm disease fungus ophiostoma novo-ulmi contains a hydrolase activity which catalyses the resolution of racemic ethyl naproxen to the corresponding acid. the recombinant enzyme has been crystallized by the vapour-diffusion method in two crystal forms. the crystals of the first form belong to space group p2(1)2(1)2, with unit-cell parameters a = 115.9, b = 174.4, c = 62.1 a. the enzyme also crystallizes in space group p2(1)2(1)2, with unit-cell parameters a = 72.9, b = 212.7, c = 61.7 a. sy ... | 2004 | 15388939 |
| selective acquisition of novel mating type and vegetative incompatibility genes via interspecies gene transfer in the globally invading eukaryote ophiostoma novo-ulmi. | the dutch elm disease fungus ophiostoma novo-ulmi, which has destroyed billions of elm trees worldwide, originally invaded europe as a series of clonal populations with a single mating type (mat-2) and a single vegetative incompatibility (vic) type. the populations then rapidly became diverse with the appearance of the mat-1 type and many vegetative incompatibility types. here, we have investigated the mechanism using isolates from sites in portugal at which the rapid evolution of o. novo-ulmi p ... | 2006 | 16367844 |
| a nine-year genetic survey of the causal agent of dutch elm disease, ophiostoma novo-ulmi in winnipeg, canada. | the causal agent of dutch elm disease, ophiostoma ulmi s. lat., has been spreading across north america since the 1920s. the population of the pathogen in winnipeg, manitoba, canada was surveyed in 1993 and 2002 using a combination of rapd marker analysis, vegetative compatibility tests, and surveys for viral double-stranded rna (dsrna). the data presented here show that the population, based on the vegetative compatibility and rapd analysis, was highly genetically uniform, and has remained so f ... | 2006 | 16617009 |
| sequence of rna-dependent rna polymerase genes provides evidence for three more distinct mitoviruses in ophiostoma novo-ulmi isolate ld. | three of the twelve double-stranded (ds) rnas, dsrnas 1a, 1b and 3b, which are located in the mitochondria of a diseased isolate, ld, of the dutch elm disease fungus, ophiostoma novo-ulmi have been cdna cloned and sequenced. examination of the sequences of the rdrp genes predicted from the nucleotide sequences of the three dsrnas suggest that they constitute the genome of three new mitoviruses. | 2006 | 16791417 |
| transgenic american elm shows reduced dutch elm disease symptoms and normal mycorrhizal colonization. | the american elm (ulmus americana l.) was once one of the most common urban trees in eastern north america until dutch-elm disease (ded), caused by the fungus ophiostoma novo-ulmi, eliminated most of the mature trees. to enhance ded resistance, agrobacterium was used to transform american elm with a transgene encoding the synthetic antimicrobial peptide esf39a, driven by a vascular promoter from american chestnut. four unique, single-copy transgenic lines were produced and regenerated into whole ... | 2007 | 17310333 |
| the sporadic occurrence of a group i intron-like element in the mtdna rnl gene of ophiostoma novo-ulmi subsp. americana. | the presence of group i intron-like elements within the u7 region of the mtdna large ribosomal subunit rna gene (rnl) was investigated in strains of ophiostoma novo-ulmi subsp. americana from canada, europe and eurasia, and in selected strains of o. ips, o. minus, o. piceae, o. ulmi, and o. himal-ulmi. this insertion is of interest as it has been linked previously to the generation of plasmid-like mtdna elements in diseased strains of o. novo-ulmi. among 197 o. novo-ulmi subsp. americana strains ... | 2008 | 18406119 |
| use of insertional mutagenesis to tag putative parasitic fitness genes in the dutch elm disease fungus ophiostoma novo-ulmi subsp. novo-ulmi. | we used insertional mutagenesis to produce genetically tagged mutants of the dutch elm disease fungus ophiostoma novo-ulmi subsp. novo-ulmi. we first optimized transformation of o. novo-ulmi protoplasts by the restriction enzyme mediated integration method. a concentration of 80 u of hindiii with 108 fungal protoplasts and 5 microg of plasmid dna was the most efficient for generating a high number of o. novo-ulmi mutants carrying a single insertion in their genome. mycelium- and yeast-like growt ... | 2008 | 18772944 |
| a satellite rna of ophiostoma novo-ulmi mitovirus 3a in hypovirulent isolates of sclerotinia homoeocarpa. | abstract two genetically distinct double-stranded rna (dsrna) elements were identified in hypovirulent isolates of sclerotinia homoeocarpa, the causal agent of dollar spot of turfgrass. the large dsrna (l-dsrna) was consistently present in all hypovirulent isolates, whereas the small dsrna (s-dsrna) was found only in some hypovirulent isolates. virulence comparisons revealed that there was no significant difference between isolates containing one or both dsrnas. therefore, the l-dsrna appears to ... | 2004 | 18943067 |
| hypovirulence-associated double-stranded rna from sclerotinia homoeocarpa is conspecific with ophiostoma novo-ulmi mitovirus 3a-ld. | abstract the nucleotide sequence of the hypovirulence-associated double-stranded rna (dsrna) in hypovirulent isolate sh12b of sclerotinia homoeocarpa, the causal agent of dollar spot of turf grass, was determined. this large dsrna (l-dsrna) is 2,632 bp long and is a and u rich (61.0% a+u residues). one strand of this dsrna contains an open reading frame (orf) with the potential to encode a protein of 720 amino acids. this orf contains 12 uga codons, predicted to encode tryptophan in ascomycete m ... | 2003 | 18944069 |
| two natural cerato-ulmin (cu)-deficient mutants of ophiostoma novo-ulmi: one has an introgressed o. ulmi cu gene, the other has an o. novo-ulmi cu gene with a mutation in an intron splice consensus sequence. | summary the nucleotide sequences of the cerato-ulmin (cu) genes of two naturally occurring pathogenic cu-deficient mutants, pg470 and maff8, of the dutch elm disease fungus, ophiostoma novo-ulmi, were determined. the pg470 cu gene sequence was identical to that of cu-secreting isolates of o. novo-ulmi, except for a g to a mutation in the gt splice consensus sequence at the start of intron 1, suggesting that the cu deficiency was due to a splicing defect in the premrna. in contrast, the maff8 cu ... | 2000 | 20572985 |
| identification of transcripts up-regulated in asexual and sexual fruiting bodies of the dutch elm disease pathogen ophiostoma novo-ulmi. | suppression subtractive hybridization cdna libraries were prepared from asexual synnemata (s-lib) and sexual perithecia (p-lib) fruiting bodies of the dutch elm disease pathogen ophiostoma novo-ulmi subsp. novo-ulmi isolate h327 (mating-type mat1-1) consisting of 630 and 401 cdna clones, respectively. both libraries were differentially screened in duplicate with forward and reverse subtracted probes. up-regulated s-lib transcripts included those with homologies to phosphoenolpyruvate carboxykina ... | 2010 | 20725133 |
| functional categorization of unique expressed sequence tags obtained from the yeast-like growth phase of the elm pathogen ophiostoma novo-ulmi. | the highly aggressive pathogenic fungus ophiostoma novo-ulmi continues to be a serious threat to the american elm (ulmus americana) in north america. extensive studies have been conducted in north america to understand the mechanisms of virulence of this introduced pathogen and its evolving population structure, with a view to identifying potential strategies for the control of dutch elm disease. as part of a larger study to examine the genomes of economically important ophiostoma spp. and the g ... | 2011 | 21864383 |
| rnaseq analysis highlights specific transcriptome signatures of yeast and mycelial growth phases in the dutch elm disease fungus ophiostoma novo-ulmi. | fungal dimorphism is a complex trait and our understanding of the ability of fungi to display different growth morphologies is limited to a small number of model species. here we study a highly aggressive dimorphic fungus, the ascomycete ophiostoma novo-ulmi, which is a model in plant pathology and the causal agent of dutch elm disease. the two growth phases that this fungus displays, i.e., a yeast phase and mycelial phase, are thought to be involved in key steps of disease development. we used ... | 2015 | 26384770 |
| a genomic comparison of putative pathogenicity-related gene families in five members of the ophiostomatales with different lifestyles. | ophiostomatoid fungi are vectored by their bark-beetle associates and colonize different host tree species. to survive and proliferate in the host, they have evolved mechanisms for detoxification and elimination of host defence compounds, efficient nutrient sequestration, and, in pathogenic species, virulence towards plants. here, we assembled a draft genome of the spruce pathogen ophiostoma bicolor. for our comparative and phylogenetic analyses, we mined the genomes of closely related species ( ... | 2017 | 28215351 |
| functional annotation of the ophiostoma novo-ulmi genome: insights into the phytopathogenicity of the fungal agent of dutch elm disease. | the ascomycete fungus ophiostoma novo-ulmi is responsible for the pandemic of dutch elm disease that has been ravaging europe and north america for 50 years. we proceeded to annotate the genome of the o. novo-ulmi strain h327 that was sequenced in 2012. the 31.784-mb nuclear genome (50.1% gc) is organized into 8 chromosomes containing a total of 8,640 protein-coding genes that we validated with rna sequencing analysis. approximately 53% of these genes have their closest match to grosmannia clavi ... | 2014 | 25539722 |
| from yeast to hypha: defining transcriptomic signatures of the morphological switch in the dimorphic fungal pathogen ophiostoma novo-ulmi. | yeast-to-hypha transition is a major morphological change in fungi. molecular regulators and pathways that are involved in this process have been extensively studied in model species, including saccharomyces cerevisiae. the mitogen-actived protein kinase (mapk) cascade, for example, is known to be involved in the yeast-to-pseudohypha switch. yet the conservation of mechanisms regulating such morphological changes in non-model fungi is still poorly understood. here, we investigate cell remodeling ... | 2016 | 27846799 |
| diversity in yeast-mycelium dimorphism response of the dutch elm disease pathogens: the inoculum size effect. | dutch elm disease (ded) is caused by the dimorphic fungi ophiostoma ulmi, ophiostoma novo-ulmi, and ophiostoma himal-ulmi. a cell population density-dependent phenomenon related to quorum sensing was previously shown to affect the reversible transition from yeast-like to mycelial growth in liquid shake cultures of o. novo-ulmi nrrl 6404. since the response to external stimuli often varies among ded fungal strains, we evaluated the effect of inoculum size on 8 strains of the 3 species of ded agen ... | 2016 | 27068623 |
| control of yeast-mycelium dimorphism in vitro in dutch elm disease fungi by manipulation of specific external stimuli. | dutch elm disease (ded) fungi exhibit yeast-mycelium dimorphism both in planta and in vitro. however, previously published data on the transition between these two growth forms in vitro were mostly obtained from a single strain. we examined the effect of six factors on yeast-mycelium dimorphism in vitro in ten strains of ophiostoma ulmi, ophiostoma novo-ulmi and ophiostoma himal-ulmi. nitrogen sources, calcium, and yeast extract, altogether with inhibitors of phosphodiesterase (caffeine) and dio ... | 2014 | 25442291 |
| geosmithia-ophiostoma: a new fungus-fungus association. | in europe as in north america, elms are devastated by dutch elm disease (ded), caused by the alien ascomycete ophiostoma novo-ulmi. pathogen dispersal and transmission are ensured by local species of bark beetles, which established a novel association with the fungus. elm bark beetles also transport the geosmithia fungi genus that is found in scolytids' galleries colonized by o. novo-ulmi. widespread horizontal gene transfer between o. novo-ulmi and geosmithia was recently observed. in order to ... | 2017 | 28875260 |
| bark and wood tissues of american elm exhibit distinct responses to dutch elm disease. | tolerance to dutch elm disease (ded) has been linked to the rapid and/or high induction of disease-responsive genes after infection with the fungus ophiostoma novo-ulmi. although the fungal infection by o. novo-ulmi primarily takes places in xylem vessels, it is still unclear how xylem contributes to the defense against ded. taking advantage of the easy separation of wood and bark tissues in young american elm saplings, here we show that most disease-responsive genes exhibited higher expression ... | 2017 | 28769110 |
| genome-wide analysis of secondary metabolite gene clusters in ophiostoma ulmi and ophiostoma novo-ulmi reveals a fujikurin-like gene cluster with a putative role in infection. | the emergence of new microbial pathogens can result in destructive outbreaks, since their hosts have limited resistance and pathogens may be excessively aggressive. described as the major ecological incident of the twentieth century, dutch elm disease, caused by ascomycete fungi from the ophiostoma genus, has caused a significant decline in elm tree populations (ulmus sp.) in north america and europe. genome sequencing of the two main causative agents of dutch elm disease (ophiostoma ulmi and op ... | 2017 | 28659888 |
| plant signals during beetle (scolytus multistriatus) feeding in american elm (ulmus americana planch). | american elms were devastated by an outbreak of dutch elm disease is caused by the fungus ophiostoma novo-ulmi brasier that originated in asia and arrived in the early 1900s. in spite of decades of study, the specific mechanisms and disease resistance in some trees is not well understood. the fungus is spread by several species of bark beetles in the genus scolytus, during their dispersal and feeding. our objective was to understand elm responses to beetle feeding in the absence of the fungus to ... | 2017 | 28448744 |
| long-term impact of ophiostoma novo-ulmi on leaf traits and transpiration of branches in the dutch elm hybrid 'dodoens'. | to better understand the long-term impact of ophiostoma novo-ulmi brasier on leaf physiology in 'dodoens', a dutch elm disease-tolerant hybrid, measurements of leaf area, leaf dry mass, petiole anatomy, petiole hydraulic conductivity, leaf and branch water potential, and branch sap flow were performed 3 years following an initial artificial inoculation. although fungal hyphae were detected in fully expanded leaves, neither anatomical nor morphological traits were affected, indicating that there ... | 2016 | 26843210 |
| establishment of invasive and non-invasive reporter systems to investigate american elm-ophiostoma novo-ulmi interactions. | dutch elm disease (ded), caused by ascomycete fungi in the ophiostoma genus, is the most devastating disease of american elm (ulmus americana) trees. cerato ulmin (cu), a hydrophobin secreted by the fungus, has been implicated in the development of ded, but its role in fungal pathogenicity and virulence remains uncertain and controversial. here, we describe reporter systems based on the cu promoter and three reporter proteins (gfp, gus and luc), developed as research tools for quantitative and q ... | 2014 | 25139300 |
| widespread horizontal transfer of the cerato-ulmin gene between ophiostoma novo-ulmi and geosmithia species. | previous work had shown that a sequence homologous to the gene encoding class ii hydrophobin cerato-ulmin from the fungus ophiostoma novo-ulmi, the causal agent of dutch elm disease (ded), was present in a strain of the unrelated species geosmithia species 5 (ascomycota: hypocreales) isolated from ulmus minor affected by ded. as both fungi occupy the same habitat, even if different ecological niches, the occurrence of horizontal gene transfer was proposed. in the present work we have analysed fo ... | 2014 | 25110129 |
| host responses and metabolic profiles of wood components in dutch elm hybrids with a contrasting tolerance to dutch elm disease. | changes occurring in the macromolecular traits of cell wall components in elm wood following attack by ophiostoma novo-ulmi, the causative agent of dutch elm disease (ded), are poorly understood. the purpose of this study was to compare host responses and the metabolic profiles of wood components for two dutch elm (ulmus) hybrids, 'groeneveld' (a susceptible clone) and 'dodoens' (a tolerant clone), that have contrasting survival strategies upon infection with the current prevalent strain of ded. | 2014 | 24854167 |
| two novel mitoviruses from a canadian isolate of the dutch elm pathogen ophiostoma novo-ulmi (93-1224). | ophiostoma novo-ulmi is the causative agent of dutch elm disease (ded). it is an ascomycetous filamentous fungus that ranks as the third most devastating fungal pathogen in canada. the disease front has spread eastward and westward from the epicentre in ontario and quebec and is threatening elm populations across the country. numerous mitigation strategies have been tried to eradicate this pathogen, but success has thus far been limited. an alternative approach might utilize double-stranded rna ... | 2013 | 23924036 |
| sequencing of the dutch elm disease fungus genome using the roche/454 gs-flx titanium system in a comparison of multiple genomics core facilities. | as part of the dna sequencing research group of the association of biomolecular resource facilities, we have tested the reproducibility of the roche/454 gs-flx titanium system at five core facilities. experience with the roche/454 system ranged from <10 to >340 sequencing runs performed. all participating sites were supplied with an aliquot of a common dna preparation and were requested to conduct sequencing at a common loading condition. the evaluation of sequencing yield and accuracy metrics w ... | 2013 | 23542132 |
| leaf trait dissimilarities between dutch elm hybrids with a contrasting tolerance to dutch elm disease. | previous studies have shown that ophiostoma novo-ulmi, the causative agent of dutch elm disease (ded), is able to colonize remote areas in infected plants of ulmus such as the leaf midrib and secondary veins. the objective of this study was to compare the performances in leaf traits between two dutch elm hybrids 'groeneveld' and 'dodoens' which possess a contrasting tolerance to ded. trait linkages were also tested with leaf mass per area (lma) and with the reduced young's modulus of elasticity ... | 2013 | 23264236 |
| chemical changes in ulmus minor xylem tissue after salicylic acid or carvacrol treatments are associated with enhanced resistance to ophiostoma novo-ulmi. | application of endogenous plant hormone salicylic acid (sa) or essential oil component carvacrol (ca) in elms enhances tree resistance to the dutch elm disease pathogen, although the effect of these compounds on tree metabolism is unknown. the chemical changes induced by sa or ca treatments in ulmus minor were studied through gas chromatography-mass spectrometry (gc-ms) analysis of xylem tissues. treatments consisted of fortnightly irrigating seedlings with water, sa or ca at 600 mg l⁻¹. the che ... | 2012 | 22910373 |
| suppression of polygalacturonase gene expression in the phytopathogenic fungus ophiostoma novo-ulmi by rna interference. | the fungal pathogen, ophiostomo novo-ulmi, has been responsible for the rapid decline of american elm (ulmus americana) across north america and remains a serious threat to surviving elm populations. the production of pectinolytic polygalacturonase enzymes has been implicated as a virulence factor for many fungal pathogens, including o. novo-ulmi. previous work has shown that the targeted disruption of the endopolygalacturonase gene locus epg1 of o. novo-ulmi reduced, but did not eliminate pecti ... | 2010 | 20176124 |
| do mites phoretic on elm bark beetles contribute to the transmission of dutch elm disease? | dutch elm disease (ded) is a destructive vascular wilt disease of elm (ulmus) trees caused by the introduced ascomycete fungus ophiostoma novo-ulmi. in europe, this ded pathogen is transmitted by elm bark beetles in the genus scolytus. these insects carry phoretic mites to new, suitable habitats. the aim of this study was to record and quantify conidia and ascospores of o. novo-ulmi on phoretic mites on the three elm bark beetle species scolytus multistriatus, scolytus pygmaeus, and scolytus sco ... | 2010 | 19967528 |
| genes within genes: multiple laglidadg homing endonucleases target the ribosomal protein s3 gene encoded within an rnl group i intron of ophiostoma and related taxa. | in some ascomycete fungi, ribosomal protein s3 (rps3) is encoded within a group i intron (ml2449) that is inserted in the u11 region of the mitochondrial large subunit rdna (rnl) gene. previous characterization of the ml2449 intron in strains of ophiostoma novo-ulmi subspecies americana (dutch elm disease) revealed a complex genes-within-genes arrangement whereby a laglidadg homing endonuclease gene (heg) is inserted into the rps3 gene near the 3' terminus, creating a hybrid rps3-laglidadg fusio ... | 2009 | 19597163 |
| fungal colonization and host defense reactions in ulmus americana callus cultures inoculated with ophiostoma novo-ulmi. | the host-pathogen interaction leading to dutch elm disease was analyzed using histo- and cyto-chemical tests in an in vitro system. friable and hard susceptible ulmus americana callus cultures were inoculated with the highly aggressive pathogen ophiostoma novo-ulmi. inoculated callus tissues were compared with water-treated callus tissues and studied with light microscopy (lm), transmission-electron microscopy (tem), and scanning-electron microscopy (sem). new aspects of this interaction are des ... | 2009 | 19453222 |
| the pathogen causing dutch elm disease makes host trees attract insect vectors. | dutch elm disease is caused by the fungal pathogen ophiostoma novo-ulmi which is transmitted by the native elm bark beetle, hylurgopinus rufipes. we have found that four semiochemicals (the monoterpene (-)-beta-pinene and the sesquiterpenes (-)-alpha-cubebene, (+)-spiroaxa-5,7-diene and (+)-delta-cadinene) from diseased american elms, ulmus americana, synergistically attract h. rufipes, and that sesquiterpene emission is upregulated in elm trees inoculated with o. novo-ulmi. the fungus thus mani ... | 2005 | 16271975 |
| metabolic distinction of ulmus minor xylem tissues after inoculation with ophiostoma novo-ulmi. | dutch elm disease (ded) is the most devastating and widespread disease of elms. the pathogen, ophiostoma novo-ulmi, spreads systemically causing xylem vessels blocking and cavitation, and ultimately resulting in the development of a wilt syndrome. twig samples from susceptible and resistant ulmus minor trees were harvested at 0, 5, 15, 30, 60, and 120 days post-inoculation (dpi) with o. novo-ulmi. fourier transform-infrared (ft-ir) spectroscopy, in tandem with chemometrics, was used to monitor c ... | 2005 | 16176827 |
| fourier transform-infrared spectroscopy as a new method for evaluating host resistance in the dutch elm disease complex. | resistance of elms (ulmus spp.) to the pathogenic fungus ophiostoma novo-ulmi brasier depends on chemical and anatomical factors that confine the spread of the pathogen in the vascular system of the host. this study focused on detecting chemical differences in 4-year-old ulmus minor mill. seedlings before and after inoculation with a virulent o. novo-ulmi isolate. according to symptom development over 60 days, the trees were divided into resistant (0-33% wilting) and susceptible (67-100% wilting ... | 2005 | 16076781 |
| seasonal changes in wood formation of ulmus pumila and u. minor and its relation with dutch elm disease. | elms containing narrow and scattered vessels have been reported to be more resistant to ophiostoma novo-ulmi (dutch elm disease pathogen) than elms with large and contiguous vessels. however, recent measurements in ulmus pumila and u. minor showed a contrary trend. the pin method was applied to 4-yr-old branches of eight clones planted in madrid. during 2002, radial growth increments and vessel diameters were measured monthly, and beetle trapping was undertaken weekly. u. minor formed larger ves ... | 2005 | 15869660 |
| correlation of resistance and h2o2 production in ulmus pumila and ulmus campestris cell suspension cultures inoculated with ophiostoma novo-ulmi. | the dutch elm disease (ded) pathogen ophiostoma novo-ulmi buissm. elicited the production of h2o2 in cell suspension cultures of the resistant species ulmus pumila l. this response was not observed in suspensions of the susceptible elm u. campestris mill. h2o2 production started after a lag time of 30-40 min following inoculation, peaked between 4 and 6 h and lasted up to 24 h. treatment of the suspensions with exogenously added h2o2 did not cause accumulation of the sesquiterpene phytoalexins m ... | 2001 | 11299016 |
| lack of association between cerato-ulmin production and virulence in ophiostoma novo-ulmi. | cerato-ulmin (cu), a hydrophobin produced by ophiostoma novo-ulmi, has been implicated in the pathogenicity of this fungus on elm. we have generated a cu- mutant by transformation-mediated gene disruption of a highly virulent (aggressive) strain of o. novo-ulmi. the inability of the mutant to synthesize cu was confirmed by transcript analysis as well as turbidity and immunological measurements. bioassay of the cu- strain in highly susceptible elm trees indicated no difference in the virulence pa ... | 1996 | 8810070 |
| nucleotide-sequence analysis indicates that a dna plasmid in a diseased isolate of ophiostoma novo-ulmi is derived by recombination between two long repeat sequences in the mitochondrial large subunit ribosomal rna gene. | the nucleotide sequence of a mitochondrial plasmid (2234 bp) in a diseased isolate of ophiostoma novo-ulmi, and sequences of the mitochondrial dna that overlap and flank the plasmid end-points, have been determined. the plasmid was shown to be derived from the o. novo-ulmi mitochondrial large subunit ribosomal rna gene and contained most of intron 1, the whole of exon 2, and probably the first part of intron 2. within intron 1 there is an open reading frame with the potential to encode a 323 ami ... | 1995 | 8536313 |
| de-novo generation of mitochondrial dna plasmids following cytoplasmic transmission of a degenerative disease in ophiostoma novo-ulmi. | a mitochondrial dna plasmid was detected in an isolate of ophiostoma novo-ulmi with a degenerative disease. the dna plasmid was shown to be derived from the mitochondrial dna and to map to a region corresponding to the large ribosomal rna coding region. the dna plasmid was not transmitted into sexual (ascospore) progeny, irrespective of whether the diseased isolate acted as the female or male parent. transmission of the disease to healthy, plasmid-free, "recipient" isolates by hyphal anastomosis ... | 1993 | 8299172 |