RESUMEN
A compact and negatively charged acceptor group, N-(cyanamino)sulfonyl, is introduced for dye design and its influence on the absorption and emission spectra of the "push-pull" chromophores is demonstrated with 1,3,6-tris[(cyanamino)sulfonyl]-8-aminopyrene. The new sulfonamides, including O-phosphorylated (3-hydroxyazetidine)-N-sulfonyl, are negatively charged electron acceptors and auxochromes. 1-Aminopyrenes decorated with the new sulfonamides have three or six negative charges (pH ≥8), low m/z ratios, high mobilities in an electric field, and yellow to orange emission. We labeled maltodextrin oligomers by reductive amination, separated the products by electrophoresis, and demonstrated their high brightness in a commercial DNA analyzer and the distribution of the emission signal among the detection channels.
RESUMEN
BACKGROUND: Whereas an increasing number of pathogenic and mutualistic ascomycetous species were sequenced in the past decade, species showing a seemingly neutral association such as root endophytes received less attention. In the present study, the genome of Phialocephala subalpina, the most frequent species of the Phialocephala fortinii s.l. - Acephala applanata species complex, was sequenced for insight in the genome structure and gene inventory of these wide-spread root endophytes. RESULTS: The genome of P. subalpina was sequenced using Roche/454 GS FLX technology and a whole genome shotgun strategy. The assembly resulted in 205 scaffolds and a genome size of 69.7 Mb. The expanded genome size in P. subalpina was not due to the proliferation of transposable elements or other repeats, as is the case with other ascomycetous genomes. Instead, P. subalpina revealed an expanded gene inventory that includes 20,173 gene models. Comparative genome analysis of P. subalpina with 13 ascomycetes shows that P. subalpina uses a versatile gene inventory including genes specific for pathogens and saprophytes. Moreover, the gene inventory for carbohydrate active enzymes (CAZymes) was expanded including genes involved in degradation of biopolymers, such as pectin, hemicellulose, cellulose and lignin. CONCLUSIONS: The analysis of a globally distributed root endophyte allowed detailed insights in the gene inventory and genome organization of a yet largely neglected group of organisms. We showed that the ubiquitous root endophyte P. subalpina has a broad gene inventory that links pathogenic and saprophytic lifestyles.
Asunto(s)
Ascomicetos/genética , Endófitos/genética , Raíces de Plantas/microbiología , Ascomicetos/metabolismo , Ascomicetos/ultraestructura , Biología Computacional/métodos , Elementos Transponibles de ADN , Endófitos/metabolismo , Endófitos/ultraestructura , Ontología de Genes , Transferencia de Gen Horizontal , Genes Fúngicos , Genoma Fúngico , Genómica/métodos , Familia de Multigenes , Interferencia de ARN , Secuencias Repetitivas de Ácidos Nucleicos , Metabolismo Secundario/genéticaRESUMEN
BACKGROUND: Mitochondrial (mt) markers are successfully applied in evolutionary biology and systematics because mt genomes often evolve faster than the nuclear genomes. In addition, they allow robust phylogenetic analysis based on conserved proteins of the oxidative phosphorylation system. In the present study we sequenced and annotated the complete mt genome of P. subalpina, a member of the Phialocephala fortinii s.l. - Acephala applanata species complex (PAC). PAC belongs to the Helotiales, which is one of the most diverse groups of ascomycetes including more than 2,000 species. The gene order was compared to deduce the mt genome evolution in the Pezizomycotina. Genetic variation in coding and intergenic regions of the mtDNA was studied for PAC to assess the usefulness of mt DNA for species diagnosis. RESULTS: The mt genome of P. subalpina is 43,742 bp long and codes for 14 mt genes associated with the oxidative phosphorylation. In addition, a GIY-YIG endonuclease, the ribosomal protein S3 (Rps3) and a putative N-acetyl-transferase were recognized. A complete set of tRNA genes as well as the large and small rRNA genes but no introns were found. All protein-coding genes were confirmed by EST sequences. The gene order in P. subalpina deviated from the gene order in Sclerotinia sclerotiorum, the only other helotialean species with a fully sequenced and annotated mt genome. Gene order analysis within Pezizomycotina suggests that the evolution of gene orders is mostly driven by transpositions. Furthermore, sequence diversity in coding and non-coding mtDNA regions in seven additional PAC species was pronounced and allowed for unequivocal species diagnosis in PAC. CONCLUSIONS: The combination of non-interrupted ORFs and EST sequences resulted in a high quality annotation of the mt genome of P. subalpina, which can be used as a reference for the annotation of other mt genomes in the Helotiales. In addition, our analyses show that mtDNA loci will be the marker of choice for future analysis of PAC communities.
Asunto(s)
Ascomicetos/genética , Evolución Molecular , Genoma Fúngico/genética , Genoma Mitocondrial/genética , Secuencia Conservada/genética , ADN Mitocondrial/genética , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Duplicación de Gen/genética , Orden Génico/genética , Reordenamiento Génico/genética , Sitios Genéticos/genética , Marcadores Genéticos , Sistemas de Lectura Abierta/genética , Filogenia , Polimorfismo Genético , Alineación de Secuencia , Especificidad de la Especie , Transcriptoma/genéticaRESUMEN
Interactions of Betula pendula and Picea abies with dark septate endophytes of the Phialocephala fortinii-Acephala applanata species complex (PAC) were studied. PAC are ubiquitous fungal root symbionts of many woody plant species but their ecological role is largely unknown. Sterile birch and spruce seedlings in monoculture and mixed culture were exposed to four PAC strains, added either singularly or paired in all possible combinations at 18°C and 23°C. Plant and fungal biomass was determined after 4 months. The most significant factors were strain and host combination. One of the strains significantly reduced biomass gain of spruce but not of birch. Plant biomass was negatively correlated with total endophytic fungal biomass in half of the strain - plant combinations. Endophytic PAC biomass was four times higher in spruce (≈ 40 mg g(-1) drw) than in birch (≈ 10 mg g(-1) drw). Competition between strains was strain-dependent with some strains significantly reducing colonization density of other strains, and, thus, attenuating adverse effects of 'pathogenic' strains on plant growth in some strain - plant combinations. Biomass gain of spruce but not of birch was significantly reduced at higher temperature. In conclusion, host, fungal genotype, colonization density and presence of a competing PAC strain were the main determining factors for plant growth.
Asunto(s)
Betula/microbiología , Picea/microbiología , Plantones/microbiología , Ascomicetos/crecimiento & desarrollo , Ascomicetos/fisiología , Betula/crecimiento & desarrollo , Biomasa , Endófitos/fisiología , Hongos , Picea/crecimiento & desarrollo , Raíces de Plantas/microbiología , Plantones/crecimiento & desarrolloRESUMEN
BACKGROUND: Fungi are asexually and sexually reproducing organisms that can combine the evolutionary advantages of the two reproductive modes. However, for many fungi the sexual cycle has never been observed in the field or in vitro and it remains unclear whether sexual reproduction is absent or cryptic. Nevertheless, there are indirect approaches to assess the occurrence of sex in a species, such as population studies, expression analysis of genes involved in mating processes and analysis of their selective constraints. The members of the Phialocephala fortinii s. l. - Acephala applanata species complex (PAC) are ascomycetes and the predominant dark septate endophytes that colonize woody plant roots. Despite their abundance in many ecosystems of the northern hemisphere, no sexual state has been identified to date and little is known about their reproductive biology, and how it shaped their evolutionary history and contributes to their ecological role in forest ecosystems. We therefore aimed at assessing the importance of sexual reproduction by indirect approaches that included molecular analyses of the mating type (MAT) genes involved in reproductive processes. RESULTS: The study included 19 PAC species and > 3, 000 strains that represented populations from different hosts, continents and ecosystems. Whereas A. applanata had a homothallic (self-fertile) MAT locus structure, all other species were structurally heterothallic (self-sterile). Compatible mating types were observed to co-occur more frequently than expected by chance. Moreover, in > 80% of the populations a 1:1 mating type ratio and gametic equilibrium were found. MAT genes were shown to evolve under strong purifying selection. CONCLUSIONS: The signature of sex was found in worldwide populations of PAC species and functionality of MAT genes is likely preserved by purifying selection. We hypothesize that cryptic sex regularely occurs in the PAC and that further field studies and in vitro crosses will lead to the discovery of the sexual state. Although structurally heterothallic species prevail, it cannot be excluded that homothallism represents the ancestral breeding system in the PAC.
Asunto(s)
Ascomicetos/genética , Ascomicetos/fisiología , Demografía , Evolución Molecular , Genes del Tipo Sexual de los Hongos/genética , Secuencia de Bases , Cartilla de ADN/genética , Genética de Población , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Reproducción/genética , Reproducción/fisiología , Selección Genética , Análisis de Secuencia de ADNRESUMEN
Root endophytes are common and genetically highly diverse suggesting important ecological roles. Yet, relative to above-ground endophytes, little is known about them. Dark septate endophytic fungi of the Phialocephala fortinii s.l.-Acephala applanata species complex (PAC) are ubiquitous root colonizers of conifers and Ericaceae, but their ecological function is largely unknown. Responses of Norway spruce seedlings of two seed provenances to inoculations with isolates of four PAC species were studied in vitro. In addition, isolates of Phialocephala subalpina from two populations within and one outside the natural range of Norway spruce were also included to study the effect of the geographic origin of P. subalpina on host response. The interaction of PAC with Norway spruce ranged from neutral to highly virulent and was primarily isolate-dependent. Variation in virulence was much higher within than among species, nonetheless only isolates of P. subalpina were highly virulent. Disease caused by P. subalpina genotypes from the native range of Norway spruce was more severe than that induced by genotypes from outside the natural distribution of Norway spruce. Virulence was not correlated with the phylogenetic relatedness of the isolates but was positively correlated with the extent of fungal colonization as measured by quantitative real-time PCR.
Asunto(s)
Ascomicetos/crecimiento & desarrollo , Endófitos/crecimiento & desarrollo , Picea/microbiología , Enfermedades de las Plantas/microbiología , Raíces de Plantas/microbiología , Ascomicetos/genética , Ascomicetos/patogenicidad , ADN de Hongos/genética , Variación Genética , Genotipo , Geografía , Filogenia , Plantones/microbiología , VirulenciaRESUMEN
Fungi of the Phialocephala fortinii sensu lato-Acephala applanata species complex (PAC) are ubiquitous endophytic colonizers of tree roots in which they form genotypically diverse communities. Measurement of the colonization density of each of the fungal colonizers is a prerequisite to study the ecology of these communities. Up to now, there is no method readily available for the quantification of PAC strains co-colonizing the same root. The new DNA quantification method presented here is based on the amplification of microsatellites by competitive polymerase chain reaction (PCR). The method proved to be suitable to detect and quantify at least two strains within one single sample by the addition of a known amount of mycelium of a reference strain before DNA extraction. The method exploits the correlation between the reference/target ratio of light emitted during microsatellite detection (peak ratio) and the reference/target ratio of mycelial weights to determine the biomass of the target strain. Hence, calibration curves were obtained by linear regression of the peak ratios on the weight ratios for different mixtures of reference and target strains. The slopes of the calibration curves and the coefficients of determination were close to 1, indicating that peak ratios are good predictors of weight ratios. Estimates of fungal biomass in mycelial test mixtures of known composition laid within the 95% prediction interval and deviated on average by 16% (maximally 50%) from the true biomass. On average, 3-6% of the root biomass of Norway spruce seedlings consisted of mycelial biomass of either one of two inoculated PAC strains. Biomass estimates obtained by real-time quantitative PCR were correlated with the estimates obtained by the microsatellite-based method, but variation between the two estimates from the same root was high in some samples. The microsatellite-based DNA quantification method described here is currently the best method for strainwise estimation of endophytic biomass of PAC fungi in small root samples.
Asunto(s)
Ascomicetos/crecimiento & desarrollo , Biomasa , Repeticiones de Microsatélite , Micelio/crecimiento & desarrollo , Micología/métodos , Ascomicetos/genética , ADN de Hongos/genética , ADN de Hongos/aislamiento & purificación , Micelio/genética , Picea/microbiología , Raíces de Plantas/microbiología , Reacción en Cadena de la Polimerasa , Análisis de RegresiónRESUMEN
A nested single-copy locus-based quantitative PCR (qPCR) assay and a multicopy locus-based qPCR assay were developed to estimate endophytic biomass of fungal root symbionts belonging to the Phialocephala fortinii sensu lato-Acephala applanata species complex (PAC). Both assays were suitable for estimation of endophytic biomass, but the nested assay was more sensitive and specific for PAC. For mycelia grown in liquid cultures, the correlation between dry weight and DNA amount was strong and statistically significant for all three examined strains, allowing accurate prediction of fungal biomass by qPCR. For mycelia colonizing cellophane or Norway spruce roots, correlation between biomass estimated by qPCR and microscopy was strain dependent and was affected by the abundance of microsclerotia. Fungal biomass estimated by qPCR and microscopy correlated well for one strain with poor microsclerotia formation but not for two strains with high microsclerotia formation. The accuracy of qPCR measurement is constrained by the variability of cell volumes, while the accuracy of microscopy can be hampered by overlapping fungal structures and lack of specificity for PAC. Nevertheless, qPCR is preferable because it is highly specific for PAC and less time-consuming than quantification by microscopy. There is currently no better method than qPCR-based quantification using calibration curves obtained from pure mycelia to predict PAC biomass in substrates. In this study, the DNA amount of A. applanata extracted from 15 mm of Norway spruce fine root segments (mean diameter, 610 microm) varied between 0.3 and 45.5 ng, which corresponds to a PAC biomass of 5.1 +/- 4.5 microg (estimate +/- 95% prediction interval) and 418 +/- 264 microg.
Asunto(s)
Ascomicetos/crecimiento & desarrollo , Ascomicetos/genética , Biomasa , Micología/métodos , Raíces de Plantas/microbiología , Reacción en Cadena de la Polimerasa/métodos , Simbiosis , Ascomicetos/aislamiento & purificación , Ascomicetos/fisiología , Medios de Cultivo/química , ADN de Hongos/análisis , ADN de Hongos/genética , Microscopía , Micelio/crecimiento & desarrollo , Picea/microbiología , Sensibilidad y EspecificidadRESUMEN
Members of the Phialocephala fortinii sensu lato -Acephala applanata species complex (PAC) are the dominant root endophytes of woody plants in temperate and boreal forests. In the present study, the mating type (MAT) idiomorphs of eight species belonging to the PAC were cloned. Because direct cloning of MAT idiomorphs was not possible, species phylogenetically placed between the PAC and other helotialean species with characterized MAT locus were used for an intermediate cloning step. Whereas A. applanata showed a homothallic organization structure of the MAT locus, all other species either contained the MAT1-1 or MAT1-2 idiomorph indicative of heterothallism. A Tc1-like transposable element was found within the MAT locus of A. applanata. Analysis of A. applanata strains collected over a broad geographical range showed that the transposable element was present in all A. applanata strains, suggesting an ancient transposition event. Moreover, a partial MAT1-1-1 gene was identified within MAT1-2 idiomorphs, a common phenomenon in the order Helotiales. However, this partial gene was not fixed in all populations of the species. The evolution of the MAT locus with regard to different mating systems is discussed for the species complex.
Asunto(s)
Ascomicetos/genética , Proteínas Fúngicas/genética , Genes del Tipo Sexual de los Hongos , Secuencia de Aminoácidos , Ascomicetos/química , Ascomicetos/clasificación , Ascomicetos/aislamiento & purificación , Mapeo Cromosómico , Proteínas Fúngicas/química , Datos de Secuencia Molecular , Filogenia , Picea/microbiología , Pinus/microbiología , Alineación de Secuencia , Árboles/microbiología , Vaccinium/microbiologíaRESUMEN
Conifer twigs showing brown felt blight were collected along 100-m long transects at the timberline in the Swiss Alps and single-hyphal-tip cultures were prepared. Forty-seven of the sequenced 48 strains were Herpotrichia juniperi based on sequence comparisons of the internal transcribed spacers (ITS). A non-sporulating strain was tentatively identified as another, undescribed Herpotrichia species. Herpotrichia coulteri was not isolated. Most strains were from Juniperus communis var. saxatilis, the rest from Picea abies and Pinus mugo. Each twig was colonized by a different genotype as revealed by ISSR-PCR fingerprinting. More than one clone was present on some needles and twigs. Thus, importance of vegetative mycelial growth for dispersal seems to be limited to the spread of the disease to twigs of the same tree or of immediately adjacent trees, and, consequently, dispersal occurs mainly by ascospores. The H. juniperi strains could be assigned to five distinct groups based on the ISSR-PCR data. The strains from P. abies formed one of these groups but the other groups did not correlate with either host, transect or position along the transects. Multi-locus analysis based on beta-tubulin, elongation factor 1-alpha and ITS sequences confirmed the subdivision into five groups. Population differentiation among groups was distinct with N(ST) values varying between 0.545 and 0.895. H. juniperi seems to be composed of several cryptic species, one of them specific to P. abies.
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Ascomicetos/clasificación , Ascomicetos/aislamiento & purificación , Enfermedades de las Plantas/microbiología , Tracheophyta/microbiología , Ascomicetos/genética , ADN de Hongos/genética , ADN Espaciador Ribosómico/genética , Proteínas Fúngicas/genética , Datos de Secuencia Molecular , FilogeniaRESUMEN
Dark, septate endophytes (DSE) were isolated from roots and needles of dwarf Picea abies and from roots of Vaccinium spp. growing on a permafrost site in the Jura Mountains in Switzerland. Two of the isolates sporulated after incubation for more than one year at 4 degrees C. One of them was a hitherto undescribed helotialean ascomycete Phaeomollisia piceae gen. sp. nov., the other was a new species of Phialocephala, P. glacialis sp. nov. Both species are closely related to DSE of the Phialocephala fortinii s. lat.-Acephala applanata species complex (PAC) as revealed by phylogenetic analyses of the ITS and 18S rDNA regions. Morphologically dissimilar fungi, such as Vibrissea and Loramyces species, are phylogenetically also closely linked to the new species and the PAC. Cadophora lagerbergii and C. (Phialophora) botulispora are moved to Phialocephala because Phialocephala dimorphospora and P. repens are the closest relatives. Several Mollisia species were closely related to the new species and the PAC according to ITS sequence comparisons. One DSE from needles of Abies alba and one from shoots of Castanea sativa formed Cystodendron anamorphs in culture. Their identical 18S sequences and almost identical ITS sequences indicated Mollisia species as closest relatives, suggesting that Mollisia species are highly euryoecious.
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Ascomicetos/genética , Filogenia , Picea/microbiología , Ascomicetos/clasificación , Ascomicetos/crecimiento & desarrollo , Ascomicetos/aislamiento & purificación , ADN de Hongos/genética , ADN Ribosómico/genética , ADN Espaciador Ribosómico/genética , Hojas de la Planta/microbiología , Raíces de Plantas/microbiología , Análisis de Secuencia de ADNRESUMEN
Phialocephala fortinii s.1. and Acephala applanata are the dominant dark septate endophytes (DSE) in roots of many trees and shrubs. Population genetic analysis led to the discovery of morphologically indistinguishable but reproductively isolated cryptic species (CSP) within Phialocephala fortinii s.1. In the present study we show that sequence data of two coding (beta-tubulin and translation elongation factor [EF-lalpha]) and three noncoding DNA loci confirm subdivision of P. fortinii s.1. and allow to differentiate seven CSP of P. fortinii. In addition we show that strains collected throughout Europe can be classified correctly based on these sequence markers. Statistically significant differences in growth response on different media were observed among CSP of P. fortinii and A. applanata. Growth inhibition on MEA amended with 100 mgl(-1) cycloheximide had the strongest differential effect of all physiological traits examined. In contrast exoenzyme production (laccase, proteinase, pectinase, phenol-oxidase, amylase, cytochrome oxidase and tyrosinase) rarely helped to differentiate CSP of P. fortinii. However A. applanata was a strong producer of amylases, laccases and proteinases. Based on these data we propose to assign species rank to six CSP of P. fortinii: P. turiciensis, P. letzii, P. europaea, P. helvetica, P. uotolensis, P. subalpina spp. nov. and P. fortinii s.s.
Asunto(s)
Ascomicetos/clasificación , Ascomicetos/genética , Ascomicetos/crecimiento & desarrollo , Ascomicetos/metabolismo , Biodiversidad , Medios de Cultivo/química , ADN de Hongos/genética , Enzimas/metabolismo , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Datos de Secuencia Molecular , Factor 1 de Elongación Peptídica/genética , Filogenia , Raíces de Plantas/microbiología , Polimorfismo de Longitud del Fragmento de Restricción , Análisis de Secuencia de ADN , Especificidad de la Especie , Esporas Fúngicas/citología , Tubulina (Proteína)/genéticaRESUMEN
Patterns of colonization of conifer roots by dark septate endopyhtes of the Phialocephala fortinii s. lat. species complex in nurseries in Switzerland and Lithuania were studied. The potential for man-mediated genotype flow was estimated for two Swiss nurseries based on customers' addresses and the number of delivered plants. Two hundred and forty-nine strains from three Swiss and five Lithuanian nurseries and an afforestation site were characterized using a combination of inter-simple sequence repeat-anchored PCR (ISSR-PCR), single-copy RFLP analysis, and sequence analysis. P. fortinii s. lat. was abundant in nursery seedlings, but the frequency of seedlings colonized varied considerably among and within nurseries. Ten cryptic species (CSP) of P. fortinii s. lat. were identified, including four hitherto undiscovered CSP. P. helvetica was the dominant species in Swiss nurseries, whereas P. fortinii s. str. was the most abundant species in Lithuanian nurseries and the afforestation site. Swiss nurseries deliver plants over distances of more than 200km indicating the high potential for man-mediated genotype flow in P. fortinii s. lat.
Asunto(s)
Ascomicetos/aislamiento & purificación , Plantones/microbiología , Árboles/microbiología , Ascomicetos/clasificación , Ascomicetos/genética , ADN de Hongos/genética , Lituania , Datos de Secuencia Molecular , Raíces de Plantas/microbiología , Polimorfismo de Longitud del Fragmento de Restricción , Análisis de Secuencia de ADN , SuizaRESUMEN
Species of the Phialocephala fortinii s.l.-Acephala applanata complex are the dominant dark septate endophytes (DSE) in roots of species belonging to the Pinaceae. The two species Phialocephala subalpina and P. fortinii s.s. belong to the most widely distributed species within this complex. In the present study, 15 polymorphic microsatellite loci were developed for these two closely related species. Strains of a community which were analysed previously using single-copy restriction fragment length polymorphism were screened with the new markers. Microsatellites were suitable to classify the two species and to recognize individuals within species.
RESUMEN
Sequence data of two coding and three non-coding loci were used to study the taxonomic identity within and relatedness among seven previously defined cryptic species (CSP) of Phialocephala fortinii and Acephala applanata using two approaches of species recognition. Identification of taxonomic groups corresponding to CSP was ambiguous in some cases when applying solely the genealogical concordance phylogenetic species recognition (GCPSR) concept. The definition of groups corresponding to CSP using GCPSR was complicated due to shared sequence haplotypes between CSP, unresolved CSP for several loci, and possible introgression. GCPSR in conjunction with a population genetic approach improved resolution significantly and the CSP status could be confirmed for all seven CSP of P. fortinii s.l. The most critical step in both analyses was the definition of groups. The combination of several classes of markers differing in resolution helped to define species boundaries.
Asunto(s)
Ascomicetos/clasificación , ADN de Hongos/genética , Micología/métodos , Ascomicetos/genética , Análisis por Conglomerados , ADN de Hongos/química , Proteínas Fúngicas/genética , Genética de Población , Datos de Secuencia Molecular , Factor 1 de Elongación Peptídica/genética , Filogenia , Reacción en Cadena de la Polimerasa/métodos , Polimorfismo de Longitud del Fragmento de Restricción , Análisis de Secuencia de ADN , Tubulina (Proteína)/genéticaRESUMEN
The genetic structure of the root endophytes Phialocephala fortinii s.l. and Acephala applanata was analyzed in two undisturbed forests. A total of 606 strains isolated from surface-sterilized, fine roots of Picea abies and Vaccinium myrtillus were examined. Two new cryptic species of P. fortinii were recognized and host specialization of A. applanata was confirmed. This species was almost exclusively isolated from roots of P. abies. The index of association did not deviate significantly from zero within any population, suggesting that recombination occurs or had occurred. Significant gene but no genotype flow was detected among study sites for P. fortinii s.l. In contrast, several isolates of A. applanata with both identical multi-locus haplotype and identical ISSR fingerprint were found in both study sites indicating genotype flow or a recent common history.
Asunto(s)
Ascomicetos/genética , Flujo Génico , Árboles/microbiología , Ascomicetos/clasificación , Ascomicetos/crecimiento & desarrollo , Genética de Población , Picea/microbiología , Raíces de Plantas/microbiología , Suiza , Vaccinium myrtillus/microbiologíaRESUMEN
Phialocephala fortinii sensu lato was isolated from Picea abies roots that had been collected from the same 3 x 3-m forest plot in 2001 and 2004, to examine the spatial and temporal dynamics of this fungal community. RFLP analysis was used to define the multilocus haplotype (MLH) of each isolate. Pielou's measure of association and chi(2) tests of independence were employed to examine the randomness of patterns of spatial distribution of MLH observed in 2001 and 2004. Population differentiation between the two samplings was tested using the G(ST) statistic. In 2001, 144 strains of 28 MLH were isolated; in 2004, 139 strains of 29 MLH. Abundant MLH in 2001 also prevailed in 2004, and the same two cryptic species were dominant in both collections. The probability of being isolated in both years increased with increasing frequency of an MLH. The patterns of spatial distribution of most MLH did not differ between years. The G(ST) values indicated identity of the two collections. Communities of P. fortinii sensu lato remain spatially and genetically stable for at least 3 yr.
Asunto(s)
Ascomicetos/fisiología , Picea/microbiología , Raíces de Plantas/microbiología , Ascomicetos/clasificación , Ascomicetos/genética , Ascomicetos/crecimiento & desarrollo , Ascomicetos/aislamiento & purificación , Southern Blotting , ADN de Hongos/genética , ADN de Hongos/aislamiento & purificación , Filogenia , Polimorfismo de Longitud del Fragmento de RestricciónRESUMEN
Acephala applanata gen. et sp. nov. is described. A. applanata is a dark-septate endophyte (DSE) of conifer roots and belongs to the Phialocephala fortinii species complex. Several genetic markers, including isozymes, inter-simple-sequence-repeat (ISSR) fingerprints, single-copy restriction fragment length polymorphisms (RFLP) and sequences of the internal transcribed spacers (ITS), let us unambiguously separate isolates of A. applanata from isolates of P. fortinii s.l. and other dark-septate endophytes. Alleles at four RFLP loci and two fixed nucleotides in the ITS region were diagnostic for A. applanata. One of the fixed nucleotides resulted in the addition of an Afa I restriction site. PCR amplification with primers prITS4 and the newly developed primer PF-ITS_F (ACT CTG AAT GTT AGT GAT GTC TGA GT) and restriction digestion with Afa I yielded three fragments (203 bp, 117 bp, 56 bp) in A. applanata but only two (260 bp and 117 bp) in P. fortinii s.l. Population differentiation (GST) between A. applanata and other cryptic species of P fortinii was pronounced, and the index of association (IA) did not deviate significantly from zero, showing that recombination occurs or had occurred in A. applanata. Although isolates of A. applanata never were observed to sporulate, it can be distinguished morphologically from P fortinii s.l. by the scarcity of aerial mycelium, significantly slower growth and denser mycelium on cellophane overlaid on water agar. These phenotypic characteristics, combined with diagnostic RFLP alleles and/or PCR-RFLP of the ITS fragment with the fixed Afa I restriction site, unequivocally allow identification of A. applanata.
Asunto(s)
Ascomicetos/genética , Ascomicetos/fisiología , Raíces de Plantas/microbiología , Simbiosis , Ascomicetos/clasificación , Ascomicetos/aislamiento & purificación , Análisis por Conglomerados , Dermatoglifia del ADN , ADN de Hongos/química , ADN de Hongos/genética , ADN de Hongos/metabolismo , ADN Espaciador Ribosómico/genética , Desoxirribonucleasas de Localización Especificada Tipo II/metabolismo , Frecuencia de los Genes , Isoenzimas/genética , Datos de Secuencia Molecular , Morfogénesis , Micelio/crecimiento & desarrollo , Filogenia , Polimorfismo de Longitud del Fragmento de Restricción , Recombinación Genética , Secuencias Repetitivas de Ácidos Nucleicos , Análisis de Secuencia de ADNRESUMEN
The genetic structure of the root-endophyte Phialocephala fortinii was analyzed in three study sites using 11 single-copy RFLP probes. A total of 541 strains isolated from surface-sterilized, fine roots (diameter 0.5-3 mm) of Norway spruce (Picea abies) were examined. The average gene diversity (H) was high in all three study sites. Cluster analysis showed that up to four well-separated clusters of multi-locus haplotypes were present within the sites. Significant population subdivision was detected among these clusters, suggesting that groups of multi-locus haplotypes were reproductively isolated and that P. fortinii is a species complex composed of several cryptic species. This hypothesis was supported by ISSR-PCR which showed clusters consistent with those of the multi-locus haplotypes identified by RFLP analysis. In contrast, ITS sequence analysis did not allow to separate the species as clearly. The index of association (IA) did not deviate significantly from zero within any cryptic species, suggesting that recombination occurs within these species. Cryptic species occurred sympatrically. Thalli of two cryptic species were detected in the same 5-mm-long root segment in one instance. No significant differentiation was observed among populations of the same cryptic species in forest stands located approximately 5 km from each other. This finding is consistent with significant gene flow over this spatial scale. In addition, several isolates with both identical multi-locus haplotype and identical ISSR fingerprint were found at each study site indicating genotype flow or a recent common history between study sites.
Asunto(s)
Ascomicetos/clasificación , Ascomicetos/genética , Recombinación Genética , Ascomicetos/aislamiento & purificación , Análisis por Conglomerados , Dermatoglifia del ADN , ADN de Hongos/análisis , ADN de Hongos/aislamiento & purificación , ADN Espaciador Ribosómico/química , ADN Espaciador Ribosómico/aislamiento & purificación , Genes Fúngicos , Variación Genética , Haplotipos , Filogenia , Picea/microbiología , Raíces de Plantas/microbiología , Reacción en Cadena de la Polimerasa , Polimorfismo de Longitud del Fragmento de Restricción , Análisis de Secuencia de ADNRESUMEN
Phenotypic and genotypic variability of 18 endophytic Guignardia strains from different host plants (Anacardiaceae: Anacardium giganteum, Myracrodruon urundeuva, Spondias mombin; Apocynaceae: Aspidosperma polyneuron; Ericaceae: Rhododendron sp.; Fabaceae: Bowdichia nitida; Leguminosae: Cassia occidentalis; Rutaceae: Citrus aurantium) growing in different sites in Brazil was assessed by means of morphometric measurements and inter-single-sequence-repeat-anchored polymerase chain reaction (ISSR-PCR) amplifications of the DNA. Morphology of conidia and ascospores and growth rates of the Brazilian isolates corresponded well with those of G. mangiferae. Multiple correspondence analysis (MCA) of the ISSR-PCR data yielded three groups of strains, which did, however, not correspond either to the host or to the geographic origin. The same individual tree hosted genotypically different strains indicating multiple infections. Phylogeny based on ITS1-5.8S-ITS2 sequence analyses confirmed conspecificity of the Brazilian isolates with G. mangiferae (syn. G. endophyllicola).