Ewald Sieverding

Hohenheim University, Stuttgart, Baden-Württemberg, Germany

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Publications (19)28.69 Total impact

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    ABSTRACT: A new Acaulospora species was isolated from the rhizosphere of Panicum maximum, Sporobolus indicus and Byrsonima crassifolia of a calcareous soil in Bayamo (Cuba). It was successfully propagated in single species cultures obtained after inoculation with multiple spores on Bracharia decumbens and Sorghum vulgare, respectively. It was also detected in several natural and agricultural sites in Northeastern Brazil. The spores are brown-yellow to yellowish brown, (50–)70–95(–112) μm in diam., and have a diagnostic pitted ornamentation on the outer surface of the structural wall layer. The pits are rounded, elliptical to elongated (vermiform or rugulate), and uniformly distributed leaving narrow bridges that regularly give the impression of a raised reticulum. Partial sequences of the LSU rRNA gene confirm the new fungus in a well separated, monophyletic clade within the Acaulosporaceae. The new fungus is here presented under the epithet Acaulospora herrerae in honor to Dr. Ricardo Herrera-Peraza, a highly appreciated former mycorrhizologist from La Habana, Cuba.
    Nova Hedwigia 01/2013; 97:401-413. · 0.81 Impact Factor
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    ABSTRACT: A new fungus in the Glomeromycetes was found in the high alpine and nival altitudes of Switzerland in the rhizosphere of several alpine plant species, with a wide soil pH range from 3.9–7.8. It forms bright yellow to dark yellow spores, 81–100 × 75–82 μm in diameter, laterally on the neck of sporiferous saccules, and has three spore walls. The outer wall is crowded with irregular pits that are 0.9–1.5 × (0.9–)1.5–3.5(–5.5) μm wide and 1.2–2.5 μm deep. Molecular analyses on the ITS region and partial LSU rDNA gene place the fungus phylogenetically in a monophyletic clade within the genus Acaulospora next to A. sieverdingii, A. paulinae, A. cavernata and A. punctata. An updated identification key for Acaulospora species is presented. The new fungus may co-occur in low frequency with species like A. alpina and A. paulinae in the alpine pastures between 2000 and 2600 m asl. However, it often is the most frequently and most abundantly found Acaulospora species at highest altitudes of plant life, i.e. at subnival and nival altitudes, where it was found in pioneer screes of shallowest soils and associated with pioneer plant species like Linaria alpina, Poa alpina and Saxifraga stellaris.
    Nova Hedwigia 01/2012; 95:105-122. · 0.81 Impact Factor
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    ABSTRACT: Concomitant morphological and molecular analyses have led to major breakthroughs in the taxonomic organization of the phylum Glomeromycota. Fungi in this phylum are known to form arbuscular mycorrhiza, and so far three classes, five orders, 14 families and 29 genera have been described. Sensulato, spore formation in 10 of the arbuscular mycorrhiza-forming genera is exclusively glomoid, one is gigasporoid, seven are scutellosporoid, four are entrophosporoid, two are acaulosporoid, and one is pacisporoid. Spore bimorphism is found in three genera, and one genus is associated with cyanobacteria. Here we present the current classification developed in several recent publications and provide a summary to facilitate the identification of taxa from genus to class level.
    IMA fungus. 12/2011; 2(2):191-9.
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    ABSTRACT: New ribosomal gene analyses reveal that Entrophospora is non-monophyletic and its type species E. infrequens closely related to Claroideoglomus species, which supports transfer of the Entrophosporaceae from Diversisporales to Glomerales as well as the 'ancestral' Claroideoglomus spp. to Albahypha gen. nov. Entrophospora baltica, supported as a separate clade within Diversisporales, is designated as type species for the new monospecific Sacculosporaceae. Entrophospora nevadensis, phylogenetically close to Diversipora spp. and Otospora bareae, is transferred to Tricispora gen. nov. (Diversiporaceae). Entrophospora, Sacculospora, and Tricispora are morphologically distinguished by spore wall structure, pattern of the two spore pore closures proximal and distal to the sporiferous saccule, and relative spore and sporiferous saccule sizes. The shape of the white hyphae subtending the spore base separates Albahypha spp. from Claroideoglomus spp.
    Mycotaxon -Ithaca Ny- 11/2011; 117:297-316. · 0.82 Impact Factor
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    ABSTRACT: Combined morphological and molecular biological analyses have achieved major advances in the taxonomy of fungal species in phylum Glomeromycota. In this study, we analyzed which species might not yet be attributed to their correct genus, focusing on Acaulospora myriocarpa , A. undulata, A. nicolsonii, and Scutellospora nodosa. Based on spore wall structure and phylogenetic support, we recombined the taxa as Archaeospora myriocarpa, Ar. undulata, Ambispora nicolsonii, and Cetraspora nodosa.
    Mycotaxon -Ithaca Ny- 11/2011; 117:429-434. · 0.82 Impact Factor
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    ABSTRACT: Species in the orders Glomerales and Diversisporales (Glomeromycetes) with glomoid spore formation are reorganized based on combined ribosomal sequence and morphological analyses. Within the Glomerales two genera in the Glomeraceae (Septoglomus, Simiglomus) and one genus in the Claroideoglomeraceae (Viscospora) are proposed as new. Paraglomerales species (thus far monogeneric) also form glomoid spores that may all germinate directly through the spore wall instead through subtending hyphae as in Glomerales.
    Mycotaxon -Ithaca Ny- 03/2011; 116:75-120. · 0.82 Impact Factor
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    ABSTRACT: Based on concomitant molecular analyses of the ribosomal gene and morphological characteristics, we divide the phylum Glomeromycota into three classes: Glomeromycetes, Archaeosporomycetes, and Paraglomeromycetes. Glomeromycetes are newly organized in three orders: Glomerales and Diversisporales, both forming typical vesicular arbuscular mycorrhiza with higher plants, and Gigasporales, forming arbuscular mycorrhiza without vesicles in the roots but with extra-radical auxiliary cells. Within the phylum, Archaeosporomycetes comprise exclusively bimorphic families and genera. The monogeneric Paraglomeromycetes species form glomoid spores that typically germinate directly through the spore wall instead through their subtending hyphae.
    Mycotaxon -Ithaca Ny- 03/2011; 116:365-379. · 0.82 Impact Factor
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    ABSTRACT: A new species of the genus Acaulospora (Glomeromycetes) was found in several mountainous to high mountainous grasslands in Switzerland and Southern Chile, at 1850–2050 m and 550–1600 m asl, respectively. The species has yellow-white to creamy and regularly globose to subglobose spores with a diameter of 105–129 μm. It is characterized by an ornamentation on the outer surface of the outer spore wall with point-like, concave and highly regular pits that are 1.1–2.0(–2.7) μm in diameter and at least as deep (1.4–3.5 μm) as wide. Phylogenetic analyses compiling partial sequences of the ITS of the ribosomal DNA place the species adjacent to A. cavernata, A. denticulata, A. paulinae and A. sieverdingii. The new fungus is described here under the epithet A. punctata. Many spores of the fungus were detected in the foreland of the retreating Morteratsch glacier near St. Moritz (Engadin, Switzerland) particularly in pioneer stands dominated by Epilobium fleischeri but also in plant-species rich older grasslands in larger distance to the glacier. It was also found in mountainous managed forests and grasslands in Southern Chile suggesting the worldwide distribution of the fungus in mountainous regions.
    Nova Hedwigia 01/2011; 93:353-362. · 0.81 Impact Factor
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    ABSTRACT: The development of communities of arbuscular mycorrhizal fungi (AMF) was investigated in the subalpine foreland of the glacier Morteratsch located at approx. 1900–2100m a.s.l. near Pontresina (Engiadin’ Ota, Switzerland). In particular, we asked if the succession of AMF communities follows or precedes the primary plant succession, and we checked the mycorrhizal status of the pioneer plant Epilobium fleischeri. Soil samples were taken at pioneer and dense grassland sites established during the last hundred years representing different periods of glacier retreat: 1875–1900, 1940–1950, 1970–1980 and 1990–2000. Extraradical hyphal length densities and AMF spore populations were analyzed in soil samples. Spore formation and mycorrhizal root colonization were monitored in trap cultures grown on Trifolium pratense, Lolium perenne, Plantago lanceolata and Hieracium pilosella or on E. fleischeri over 14 months. We found that E. fleischeri is strongly arbuscular mycorrhizal, but plants in closest distance to the glacier (glacier retreat in the last 4–6 years before sampling) were non-mycorrhizal. Spore densities and root colonization in trap cultures were generally low in samples from glacier stage 1990–2000. Highest spore density and colonization were found for the sites ice-free since 1970–1980, whilst highest AMF species richness and hyphal length densities were found at the sites ice-free since 1875–1900. Our findings show an establishment of a few AMF pioneer species (e.g. Diversispora versiformis and Acaulospora punctata) within 5–10 years and species rich AMF communities at sites ice-free for 100 years (28 species). Their succession generally follows the succession of the plant communities. We conclude that AMF pioneer species might be mainly distributed by wind transport while other AMF fungi (e.g. Glomus rubiforme and Glomus aureum) rather need a below-ground hyphal network to invade new areas.
    Pedobiologia 01/2011; 54(5):321-331. · 1.69 Impact Factor
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    ABSTRACT: The objective of this study was to test whether soil types can be characterized by their arbuscular mycorrhizal fungal (AMF) communities. To answer this question, a well-defined study area in the temperate climatic zone of Central Europe was chosen with a large spectrum of soils and parent materials. Representative soil samples were taken from three soil types (Cambisol, Fluvisol and Leptosol) at in total 16 sites differing in agricultural land use intensity (9 grasslands and 7 arable lands). AMF spores were isolated and morphologically identified directly from field soils and after reproduction in trap cultures. AMF diversity and community composition strongly depended on soil type and land use intensity, and several AMF species were characteristic for a specific soil type or a specific land use type and hence had a specific niche. In contrast, other AM fungi could be considered as ‘generalists’ as they were present in each soil type investigated, irrespective of land use intensity. An estimated 53% of the 61 observed AMF species could be classified as ‘specialists’ as (almost) exclusively found in specific soil types and/or under specific land use intensities; 28% appeared to be ‘generalists’ and 19% could not be classified. Plant species compositions (either natural or planted) had only a subordinate influence on the AMF communities. In conclusion, land use intensity and soil type strongly affected AMF community composition as well as the presence and prevalence of many AM fungi. Future work should examine how the differences in AMF species compositions affect important ecosystem processes in different soils and to which extent the loss of specific groups of AM fungi affect soil quality.
    Soil Biology & Biochemistry - SOIL BIOL BIOCHEM. 01/2010; 42(5):724-738.
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    ABSTRACT: The occurrence of arbuscular mycorrhizal fungi (AMF) was assessed by both morphological and molecular criteria in two salt marshes: (i) a NaCl site of the island Terschelling, Atlantic Coast, the Netherlands and (ii) a K(2)CO(3) marsh at Schreyahn, Northern Germany. The overall biodiversity of AMF, based on sequence analysis, was comparably low in roots at both sites. However, the morphological spore analyses from soil samples of both sites exhibited a higher AMF biodiversity. Glomus geosporum was the only fungus of the Glomerales that was detected both as spores in soil samples and in roots of the AMF-colonized salt plants Aster tripolium and Puccinellia sp. at both saline sites and on all sampling dates (one exception). In roots, sequences of Glomus intraradices prevailed, but this fungus could not be identified unambiguously from DNA of soil spores. Likewise, Glomus sp. uncultured, only deposited as sequence in the database, was widely detected by DNA sequencing in root samples. All attempts to obtain the corresponding sequences from spores isolated from soil samples failed consistently. A small sized Archaeospora sp. was detected, either/or by morphological and molecular analyses, in roots or soil spores, in dead AMF spores or orobatid mites. The study noted inconsistencies between morphological characterization and identification by DNA sequencing of the 5.8S rDNA-ITS2 region or part of the 18S rDNA gene. The distribution of AMF unlikely followed the salt gradient at both sites, in contrast to the zone formation of plant species. Zygotes of the alga Vaucheria erythrospora (Xanthophyceae) were retrieved and should not be misidentified with AMF spores.
    Environmental Microbiology 03/2009; 11(6):1548-61. · 5.76 Impact Factor
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    ABSTRACT: The aim of this study was to investigate sporulation dynamics of arbuscular mycorrhizal fungal (AMF) communities from agroecosystems differing in land use intensity in long-term experimental microcosms. These were set up with characteristic grassland plants (Lolium perenne, Trifolium pratense, Plantago lanceolata), and inoculated with soils from several grasslands and arable lands subjected to crop rotation or continuous monocropping. The microcosms were maintained under ambient light and temperature conditions over 3 years. A novel, localized sampling scheme was applied for attaining exclusively the newly formed spores at bimonthly intervals. Overall, 39 AMF species were detected by morphological spore identification. Some species were recovered from all sites, others exclusively from arable lands, or grasslands, or from all sites except under maize monocropping. Clear seasonal and successional AMF sporulation dynamics were revealed, implying different life strategies of different AMF species. A first group of Glomus spp., including G. mosseae, sporulated rapidly during the first season. A second group, including G. constrictum and G. fasciculatum, sporulated late in the first season and replaced the first group during subsequent seasons. A large third group, including G. invermaium, G. macrocarpum and G. sinuosum, sporulated much later, in the second or third season. Acaulospora, Archaeospora and Ambispora spp. sporulated mainly during spring and early summer, Scutellospora and Cetraspora spp. only in fall. While in the microcosms derived from arable lands, cumulative species numbers did not increase anymore after 2 years, the numbers still increased significantly in the microcosms from the grasslands indicating longer lasting periods of sporulation cycles. Remarkably, the arable land under organic farming produced the highest AMF species richness, even higher than the grasslands. In conclusion, AMF communities from distinct agro-ecosystems differed in species composition and seasonal and successional sporulation dynamics.
    Agriculture Ecosystems & Environment - AGR ECOSYST ENVIRON. 01/2009; 134(3):257-268.
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    ABSTRACT: Acaulospora alpina sp. nov. forms small (65-85 microm diam), dark yellow to orange-brown spores laterally on the neck of hyaline to subhyaline sporiferous saccules. The spores have a three-layered outer spore wall, a bi-layered middle wall and a three-layered inner wall. The surface of the second layer of the outer spore wall is ornamented, having regular, circular pits (1.5-2 microm diam) that are as deep as wide and truncated conical. A "beaded" wall layer as found in most other Acaulospora spp. is lacking. The spore morphology of A. alpina resembles that of A. paulinae but can be differentiated easily by the unique ornamentation with the characteristic pits and by the spore color. A key is presented summarizing the morphological differences among Acaulospora species with an ornamented outer spore wall. Partial DNA sequences of the ITS1, 5.8S subunit and ITS2 regions of ribosomal DNA show that A. alpina and A. paulinae are not closely related. Acaulospora lacunosa, which has similar color but has generally bigger spores, also has distinct rDNA sequences. Acaulospora alpina is a characteristic member of the arbuscular mycorrhizal fungal communities in soils with pH 3.5-6.5 in grasslands of the Swiss Alps at altitudes between 1800 and 2700 m above sea level. It is less frequent at 1300-1800 m above sea level, and it so far has not been found in the Alps below 1300 m or in the lowlands of Switzerland.
    Mycologia 01/2006; 98(2):286-94. · 2.11 Impact Factor
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    ABSTRACT: The vertical distribution of spores of arbuscular mycorrhizal fungi (AMF) was investigated in soil profiles of extensively and intensively managed agroecosystems, including two permanent grasslands, a vineyard and two continuously mono-cropped maize fields. The number of AMF spores decreased with increasing soil depth--most drastically in the grasslands and the vineyard--but there was a large diversity of AMF species even in the deepest soil layers (50-70 cm). This was particularly striking in the maize fields where the highest species numbers were found below ploughing depth. Some species sporulated mainly, or exclusively, in the deep soil layers, others mainly in the top layers. Soil samples were used to inoculate trap cultures. Up to 18 months after inoculation, there was no conspicuous difference in the species composition among the trap cultures representing different soil depths, and only a weak match to the species composition determined by analysis of field samples. Our results indicate that the AMF communities in deep soil layers are surprisingly diverse and different from the topsoil. Thus, deep soil layers should be included in studies to get a complete picture of AMF diversity.
    New Phytologist 02/2005; 165(1):273-83. · 6.74 Impact Factor
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    F. Oehl, D. Redecker, E. Sieverding
    01/2005;
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    E Sieverding, F Oehl
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    ABSTRACT: Arbuscular mycorrhizal fungal (AMF) species are soil born. They are obligate symbionts and they require a root of a higher plant to grow and to reproduce. Thus, they occur only under vegetation, or where plants grew. Some of the so far 190 species described can be considered to be generalists, e.g. Glomus mosseae, G. geosporum, G. etunicatum, G. constrictum, G. diaphanum, G. fasciculatum and Scutellospora calospora because they have been found in divers ecosystems. These, thus, must be considered to have invasive capabilities. Others are non-generalists only occurring under e.g. grassland vegetation. Extremely little is known about the natural invasion process of these fungi into an ecosystem. Newly formed pioneer vegetation in areas without former plant cover appear to become slowly colonized. Long-distance transport of AMF propagules can be by wind and water and potentially also by agricultural goods as carrier. Once established in an area the speed of local distribution is slow, often slower than root growth. Specific AMF species can persist several years in the soil even without a host plant. Successional changes of the composition of the native AMF species composition are known from agro-ecosystems, and these changes are strongly influenced by agricultural practices. Some practices dramatically decrease the biodiversity of the AMF species community. The invasion of AMF into areas of low AMF propagule density is seen to be positive for plant growth. It is speculated that the introduction of a 'foreign' AMF species does not have a negative impact on the ecology of an existing ecosystem with its existing AMF species community.
    01/2005;
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    ABSTRACT: Previous work has shown considerably enhanced soil fertility in agroecosystems managed by organic farming as compared to conventional farming. Arbuscular mycorrhizal fungi (AMF) play a crucial role in nutrient acquisition and soil fertility. The objective of this study was to investigate the diversity of AMF in the context of a long-term study in which replicated field plots, at a single site in Central Europe, had been cultivated for 22 years according to two "organic" and two "conventional" farming systems. In the 23rd year, the field plots, carrying an 18-month-old grass-clover stand, were examined in two ways with respect to AMF diversity. Firstly, AMF spores were isolated and morphologically identified from soil samples. The study revealed that the AMF spore abundance and species diversity was significantly higher in the organic than in the conventional systems. Furthermore, the AMF community differed in the conventional and organic systems: Glomus species were similarly abundant in all systems but spores of Acaulospora and Scutellospora species were more abundant in the organic systems. Secondly, the soils were used to establish AMF-trap cultures using a consortium of Plantago lanceolata, Trifolium pratense and Lolium perenne as host plants. The AMF spore community developing in the trap cultures differed: after 12 months, two species of the Acaulosporaceae (A. paulinae and A. longula) were consistently found to account for a large part of the spore community in the trap cultures from the organic systems but were found rarely in the ones from the conventional systems. The findings show that some AMF species present in natural ecosystems are maintained under organic farming but severely depressed under conventional farming, indicating a potentially severe loss of ecosystem function under conventional farming.
    Oecologia 04/2004; 138(4):574-83. · 3.01 Impact Factor
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    ABSTRACT: The impact of land use intensity on the diversity of arbuscular mycorrhizal fungi (AMF) was investigated at eight sites in the "three-country corner" of France, Germany, and Switzerland. Three sites were low-input, species-rich grasslands. Two sites represented low- to moderate-input farming with a 7-year crop rotation, and three sites represented high-input continuous maize monocropping. Representative soil samples were taken, and the AMF spores present were morphologically identified and counted. The same soil samples also served as inocula for "AMF trap cultures" with Plantago lanceolata, Trifolium pratense, and Lolium perenne. These trap cultures were established in pots in a greenhouse, and AMF root colonization and spore formation were monitored over 8 months. For the field samples, the numbers of AMF spores and species were highest in the grasslands, lower in the low- and moderate-input arable lands, and lowest in the lands with intensive continuous maize monocropping. Some AMF species occurred at all sites ("generalists"); most of them were prevalent in the intensively managed arable lands. Many other species, particularly those forming sporocarps, appeared to be specialists for grasslands. Only a few species were specialized on the arable lands with crop rotation, and only one species was restricted to the high-input maize sites. In the trap culture experiment, the rate of root colonization by AMF was highest with inocula from the permanent grasslands and lowest with those from the high-input monocropping sites. In contrast, AMF spore formation was slowest with the former inocula and fastest with the latter inocula. In conclusion, the increased land use intensity was correlated with a decrease in AMF species richness and with a preferential selection of species that colonized roots slowly but formed spores rapidly.
    Applied and Environmental Microbiology 06/2003; 69(5):2816-24. · 3.68 Impact Factor

Publication Stats

538 Citations
732 Downloads
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28.69 Total Impact Points

Institutions

  • 2004–2013
    • Hohenheim University
      • Institute of Plant Production and Agroecology in the Tropics and Subtropics
      Stuttgart, Baden-Württemberg, Germany
  • 2003–2006
    • Universität Basel
      • Botanical Institute
      Basel, BS, Switzerland