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Stéphane Declerck - One of the best experts on this subject based on the ideXlab platform.
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Fungicides With Contrasting Mode of Action Differentially Affect Hyphal Healing Mechanism in Gigaspora sp. and Rhizophagus irregularis
Frontiers in plant science, 2021Co-Authors: Victor Hugo Rodriguez-morelos, Maryline Calonne-salmon, Vincent Bremhorst, Mónica Garcés-ruiz, Stéphane DeclerckAbstract:Fungicides are widely used in conventional agriculture to control fungal diseases, but may also affect non-target microorganisms such as arbuscular mycorrhizal (AM) fungi. These root symbionts develop extended mycelial networks within the soil via mechanisms such as anastomosis that indistinctly concerns intact and damaged hyphae, the latter being named hyphal healing mechanism (HHM). The HHM differs between Glomeraceae and Gigasporaceae. However, the effects of fungicides on this mechanism in unknown. Here, the impact of azoxystrobin, pencycuron, flutolanil and fenpropimorph at 0.02 and 2 mg L−1 were tested in vitro on the HHM of Gigaspora sp. MUCL 52331 and Rhizophagus irregularis MUCL 41833, and repair events visualized carefully under a dissecting bright-field light microscope. Azoxystrobin was the more detrimental for both AM fungi at 2 mg L−1, while fenpropimorph impacted only R. irregularis (stimulating at low and inhibiting at high concentration). Conversely, flutolanil and pencycuron did not impact any of the two AMF fungi. The mechanisms involved remains to be elucidated, but perturbation in the still-to-be firmly demonstrated spitzenkorper or in sterols content as well as a process of hormesis are possible avenues that deserve to be explored in view of a rationale management of chemicals to control fungal pathogens without harming the beneficial AM fungi.
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Hyphal healing mechanism in the arbuscular mycorrhizal fungi Scutellospora reticulata and Glomus clarum differs in response to severe physical stress.
FEMS microbiology letters, 2007Co-Authors: Ivan Enrique De La Providencia, F. Fernández, Stéphane DeclerckAbstract:The hyphal healing mechanism (HHM) has been shown to differ between Gigasporaceae and Glomeraceae. However, this process has not been considered under (severe) physical stress conditions. Scutellospora reticulata and Glomus clarum strains were cultured monoxenically. The impact of long distance separating cut extremities of hyphae and of multiple injuries within hyphae on the HHM was monitored. For long distances (> 5000 mu m) separating cut extremities, hyphae healing was observed in half the cases in S. reticulata and was absent in G. clarum. For multiple-injured hyphae, the HHM was always oriented towards the complete recovery of hyphae integrity in S. reticulata, while in G. clarum, the growing hyphal tips (GHTs) could indifferently reconnect cut sections, by-pass cut sections or develop into the environment. Hyphae behaviour under severe physical stress clearly differentiated S. reticulata from G. clarum, suggesting that both fungi have developed different strategies for colony growth to survive under adverse conditions.
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Life History Strategies in Gigasporaceae: insight from monoxenic culture
Soil Biology, 2005Co-Authors: Francisco Adriano De Souza, Stéphane Declerck, Yolande Dalpé, Ivan Enrique De La Providencia, Nathalie Séjalon-delmasAbstract:During the past years, there has been an increased interest in the role of arbuscular mycorrhizal (AM) fungal biodiversity for the functioning of terrestrial ecosystems and in the application of AM fungal technology for agricultural and land rehabilitation schemes. However, one major bottleneck in AM research is the lack of knowledge on ecology, and in particular on life history strategies (LHS) among the different AM fungal families (Hart et al. 2001; Hart and Klironomos 2002). The LHS of an organism is a product of its evolutionary past, and is expressed in the fungal life cycle, i.e. patterns of growth, differentiation, storage and, especially, reproduction (Begon et al. 1996). In order to understandAM fungal ecology, it is central to appreciate species life history traits and genetic diversity. Monoxenic cultures of AM fungi are exploited here to study these issues, with special emphasis on the family Gigasporaceae.
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Arbuscular mycorrhizal fungi reveal distinct patterns of anastomosis formation and hyphal healing mechanisms between different phylogenic groups.
The New phytologist, 2004Co-Authors: Ivan Enrique De La Providencia, Francisco Adriano De Souza, F. Fernández, Nathalie Séjalon Delmas, Stéphane DeclerckAbstract:The significance of anastomosis formation and the hyphal healing mechanism (HHM) for functionality and integrity of the arbuscular mycorrhizal (AM) fungal mycelial network remains poorly documented. Four Glomeraceae and three Gigasporaceae were cultured monoxenically. Anastomosis formation was assessed using the grid line method, while HHM was time-lapse monitored. In intact mycelial networks, the number of anastomosis per hyphal length was higher for Glomeraceae than for Gigasporaceae strains. Glomeraceae strains studied always formed anastomosis between different hyphae, whereas anastomosis in the Gigasporaceae more often concerned hyphal bridges within the same hyphae. In both families the HHM corresponded to a four-step process; first septum formation; second initiation of growing hyphal tips (GHTs); third GHT elongation, orientation and contact; and fourth GHT fusion and cytoplasmic/protoplasmic flux re-establishment. These four steps differentiated Glomeraceae from Gigasporaceae. The type and number of anastomosis per hyphal length, and the HHM differed considerably between Glomeraceae and Gigasporaceae families representing a supplementary character that distinguishes these two families and may be of significance in ecological studies of AM fungi.
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Mycelium Development and Architecture, and Spore Production of Scutellospora reticulata in Monoxenic Culture with Ri T-DNA Transformed Carrot Roots
Mycologia, 2003Co-Authors: Francisco Adriano De Souza, Stéphane DeclerckAbstract:Mycelium development and architecture and spore production were studied in Scutellospora reticulata from single-spore isolates grown with Ri T-DNA transformed carrot root-organ culture in monoxenic system. Culture establishment, anastomosis occurrence and auxiliary cell development also were examined. Seventy percent of the pregerminated disinfected spores colonized the transformed carrot roots. After 8 mo, the average spore production was 56 (24–130) per 30 cm3 of medium. Of the spores produced, 75% germinated and produced new generations in monoxenic culture. The mycelium network was formed by thick light-brown hyphae, which exhibit two major architecture patterns related to either root colonization or resource exploitation, and lower-order hyphae, bearing auxiliary cells, branched absorbing structures (BAS), hyphal swellings (HS) and forming anastomoses. BAS were formed abundantly in extramatrical mycelium and frequently had HS resembling vesicles, a feature not previously reported in the Gigasporaceae, to the best of our knowledge. Few anastomosis were observed within the mycelium and most often corresponded to a healing mechanism that form hypha bridges to reconnect broken hyphae or overcoming obstructed areas within a hypha. Numerous auxiliary cells were produced during culture development and their role was inferred. [KEYWORDS: anastomosis, arbuscular mycorrhizal fungi, auxiliary cell, branched absorbing structures, Gigasporaceae, Glomeromycota, hyphal swelling, monoxenic culture
Francisco Adriano De Souza - One of the best experts on this subject based on the ideXlab platform.
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Arbuscular mycorrhizal fungal diversity in rhizosphere spores versus roots of an endangered endemic tree from Argentina: Is fungal diversity similar among forest disturbance types?
Applied Soil Ecology, 2016Co-Authors: Florencia Soteras, Nicolás Pastor, Flávia Carneiro Mendes, Daniele Ruela Mendes, Francisco Adriano De Souza, Gabriel Grilli, Bruno Coutinho Moreira, Maria Catarina Megumi Kasuya, Daniel Renison, Alejandra G. BecerraAbstract:Abstract The aim of this study was to compare the arbuscular mycorrhizal fungal (AMF) community of the rhizosphere and inside the roots of the perennial Polylepis australis tree. Three forest types differing in their structural complexity due to anthropogenic disturbances were chosen at three different sites at the high mountains of central Argentina. Rhizosphere spores and P. australis roots of four randomly selected trees were isolated from 36 soil samples, DNA was extracted and the 18S rDNA fragments were amplified by nested-PCR. The products were analyzed by DGGE and the bands were excised for sequencing. In total, 36 OTUs were defined from 56 DGGE bands successfully sequenced. Forest disturbance types showed similar communities of AMF, as rhizosphere spores and within the roots of P. australis. However, DGGE clustering showed mainly differences between rhizosphere spores and root-colonizing AMF. Members of Glomeraceae, Pacisporaceae, Acaulosporaceae and Gigasporaceae were shown in rhizosphere spore samples. Root samples showed only members of Acaulosporaceae and Gigasporaceae, which might be complementary in terms of soil resources exploration. The prevalence of the root system with their community of symbionts might explain the resilience of AMF soil communities to forests structural changes. This study presents evidence of a possible preference in the AMF–P. australis interaction.
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Arbuscular mycorrhizal fungal diversity in rhizosphere spores versus roots of an endangered endemic tree from Argentina: Is fungal diversity similar among forest disturbance types?
'Elsevier BV', 2016Co-Authors: Soteras, María Florencia, Francisco Adriano De Souza, Moreira, Bruno Coutinho, Grilli Gabriel, Pastor Nicolás, Mendes, Flávia Carneiro, Daniela Ruela De ,carvalho, Renison Daniel, Kasuya, Maria Catarina Megumi, Becerra, Alejandra GabrielaAbstract:The aim of this study was to compare the arbuscular mycorrhizalfungal (AMF) community of the rhizosphere and inside the roots of theperennial Polylepis australis tree. Three forest types differing in theirstructural complexity due to anthropogenic disturbances were chosen atthree different sites at the high mountains of central Argentina.Rhizosphere spores and P. australis roots of four randomly selected treeswere isolated from 36 soil samples, DNA was extracted and the 18S rDNAfragments were amplified by nested-PCR. The products were analyzed byDGGE and the bands were excised for sequencing. In total, 36 OTUs weredefined from 56 DGGE bands successfully sequenced. Forest disturbancetypes showed similar communities of AMF, as rhizosphere spores and withinthe roots of P. australis. However, DGGE clustering showed mainlydifferences between rhizosphere spores and root-colonizing AMF. Membersof Glomeraceae, Pacisporaceae, Acaulosporaceae and Gigasporaceae wereshown in rhizosphere spore samples. Root samples showed only members ofAcaulosporaceae and Gigasporaceae, which might be complementary in termsof soil resources exploration. The prevalence of the root system withtheir community of symbionts might explain the resilience of AMF soilcommunities to forests structural changes. This study presents evidenceof a possible preference in the AMF- P. australis interaction.Fil: Soteras, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Moreira, Bruno Coutinho. Universidade Federal de Viçosa; BrasilFil: Grilli, Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Pastor, Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Mendes, Flávia Carneiro. Universidade Federal de Viçosa; BrasilFil: Carvalho, Daniela Ruela de. Universidade Federal de Viçosa; BrasilFil: Renison, Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; ArgentinaFil: Kasuya, Maria Catarina Megumi. Universidade Federal de Viçosa; BrasilFil: Souza, Francisco Adriano de. Núcleo de Biologia Aplicada; BrasilFil: Becerra, Alejandra Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentin
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Life History Strategies in Gigasporaceae: insight from monoxenic culture
Soil Biology, 2005Co-Authors: Francisco Adriano De Souza, Stéphane Declerck, Yolande Dalpé, Ivan Enrique De La Providencia, Nathalie Séjalon-delmasAbstract:During the past years, there has been an increased interest in the role of arbuscular mycorrhizal (AM) fungal biodiversity for the functioning of terrestrial ecosystems and in the application of AM fungal technology for agricultural and land rehabilitation schemes. However, one major bottleneck in AM research is the lack of knowledge on ecology, and in particular on life history strategies (LHS) among the different AM fungal families (Hart et al. 2001; Hart and Klironomos 2002). The LHS of an organism is a product of its evolutionary past, and is expressed in the fungal life cycle, i.e. patterns of growth, differentiation, storage and, especially, reproduction (Begon et al. 1996). In order to understandAM fungal ecology, it is central to appreciate species life history traits and genetic diversity. Monoxenic cultures of AM fungi are exploited here to study these issues, with special emphasis on the family Gigasporaceae.
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Arbuscular mycorrhizal fungi reveal distinct patterns of anastomosis formation and hyphal healing mechanisms between different phylogenic groups.
The New phytologist, 2004Co-Authors: Ivan Enrique De La Providencia, Francisco Adriano De Souza, F. Fernández, Nathalie Séjalon Delmas, Stéphane DeclerckAbstract:The significance of anastomosis formation and the hyphal healing mechanism (HHM) for functionality and integrity of the arbuscular mycorrhizal (AM) fungal mycelial network remains poorly documented. Four Glomeraceae and three Gigasporaceae were cultured monoxenically. Anastomosis formation was assessed using the grid line method, while HHM was time-lapse monitored. In intact mycelial networks, the number of anastomosis per hyphal length was higher for Glomeraceae than for Gigasporaceae strains. Glomeraceae strains studied always formed anastomosis between different hyphae, whereas anastomosis in the Gigasporaceae more often concerned hyphal bridges within the same hyphae. In both families the HHM corresponded to a four-step process; first septum formation; second initiation of growing hyphal tips (GHTs); third GHT elongation, orientation and contact; and fourth GHT fusion and cytoplasmic/protoplasmic flux re-establishment. These four steps differentiated Glomeraceae from Gigasporaceae. The type and number of anastomosis per hyphal length, and the HHM differed considerably between Glomeraceae and Gigasporaceae families representing a supplementary character that distinguishes these two families and may be of significance in ecological studies of AM fungi.
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PCR-Denaturing Gradient Gel Electrophoresis Profiling of Inter- and Intraspecies 18S rRNA Gene Sequence Heterogeneity Is an Accurate and Sensitive Method To Assess Species Diversity of Arbuscular Mycorrhizal Fungi of the Genus Gigaspora
Applied and environmental microbiology, 2004Co-Authors: Francisco Adriano De Souza, George A. Kowalchuk, Paula Leeflang, Johannes A. Van Veen, Eric SmitAbstract:Despite the importance of arbuscular mycorrhizal fungi in the majority of terrestrial ecosystems, their ecology, genetics, and evolution are poorly understood, partly due to difficulties associated with detecting and identifying species. We explored the inter- and intraspecies variations of the 18S rRNA genes of the genus Gigaspora to assess the use of this marker for the discrimination of Gigaspora isolates and of Gigasporaceae populations from environmental samples. Screening of 48 Gigaspora isolates by PCR-denaturing gradient gel electrophoresis (DGGE) revealed that the V3-V4 region of the 18S rRNA gene contained insufficient variation to discriminate between different Gigaspora species. In contrast, the patterns of 18S ribosomal DNA (rDNA) heterogeneity within the V9 region of this marker could be used for reliable identification of all recognized species within this genus. PCR-DGGE patterns provided insight into some putative misidentifications and could be used to differentiate geographic isolates of G. albida, G. gigantea, and G. margarita but not G. rosea. Two major clusters were apparent based upon PCR-DGGE ribotype patterns, one containing G. albida, G. candida, G. ramisporophora, and G. rosea and the other containing G. decipiens and G. margarita. Dissection of the DGGE patterns by cloning, DGGE screening, and sequencing confirmed these groupings and revealed that some ribotypes were shared across species boundaries. Of the 48 isolates examined, only two displayed any spore-to-spore variation, and these exceptions may be indicative of coisolation of more than one species or subspecies within these cultures. Two Brazilian agricultural soils were also analyzed with a Gigasporaceae-specific nested PCR approach, revealing a dominance of G. margarita within this family.
Florencia Soteras - One of the best experts on this subject based on the ideXlab platform.
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Arbuscular Mycorrhizal Fungal Communities of High Mountain Ecosystems of South America: Relationship with Microscale and Macroscale Factors
Fungal Biology, 2019Co-Authors: Florencia Soteras, Gabriel Grilli, Eugenia Menoyo, Alejandra Gabriela BecerraAbstract:The high mountain ecosystems of South America represent one of the main hotspots of biodiversity. There is an increasing interest in disentangling global patterns of arbuscular mycorrhizal fungi (AMF). Recently studies postulated that the majority of AMF taxa are cosmopolitan, although community composition changes depend on microscale and macroscale factors. In this Chapter we reviewed the studies performed at high mountain ecosystems of South America analyzing the richness of morphospecies and structure of AMF communties in relation to microscale (host species, pH, N, P) and macroscale factors (latitude, temperature, precipitation). AMF communities differed in both scales being associated with sampling site, vegetation type or host identity. Glomeraceae and Gigasporaceae families were related to micro- and macro-scale factors, while Acaulosporaceae did not show significant relationships with neither micro- nor with macro-scale factors. At higher scales, AMF community composition of tropical and temperate ecosystems differed due to latitude, precipitation and temperature. Meanwhile, at lower scales soil characteristics and host species became the most relevant factors in differentiating AMF composition of sites. AMF communities of high mountain forests of South America are differentially affected by the particular characteristics of these environments different from the cosmopolitan pattern.
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Biodiversity of Arbuscular Mycorrhizal Fungi in South America: A Review
Fungal Biology, 2019Co-Authors: M. Noelia Cofré, Florencia Soteras, Marta Noemi Cabello, M. Del Rosario Iglesias, Silvana Velázquez, Camila Lucía Abarca, Lucía Risio, Emanuel Ontivero, Laura S. Domínguez, Mónica A. LugoAbstract:Arbuscular mycorrhizal fungi (AMF) are a cosmopolitan group of root symbionts associated with about 80% of earth plants. Current morphological and molecular classification describes around 300 and 1000 AMF taxa respectively. Despite the communities of AMF of many ecological divisions, biomes and ecosystems remain entirely unstudied, cumulative information has increased considerably over the last years, particularly for South America (SA). In this Chapter we reviewed the published literature of AMF morphological richness for SA in order to evaluate richness patterns across the ecological divisions of the region. The compiled data included 2187 records. The 186 morphological taxa identified in the literature evidenced an increasing interest in the study of these fungi in the region, yet with an uneven distribution among ecodivisions within the Amazonia, Atlantic forest, Caatinga and Chaco, which were the main research focus. Glomeraceae species predominated in all ecodivisions with Acaulosporaceae and Gigasporaceae alternated as the second predominant family. It is difficult to draw broad scale conclusions about richness changes among ecological divisions in SA as there are many that remain unstudied and others poorly sampled (e.g. Guianan lowlands and Patagonia respectively). Therefore, further studies of these ecosystems should be encouraged.
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Arbuscular mycorrhizal fungal diversity in rhizosphere spores versus roots of an endangered endemic tree from Argentina: Is fungal diversity similar among forest disturbance types?
Applied Soil Ecology, 2016Co-Authors: Florencia Soteras, Nicolás Pastor, Flávia Carneiro Mendes, Daniele Ruela Mendes, Francisco Adriano De Souza, Gabriel Grilli, Bruno Coutinho Moreira, Maria Catarina Megumi Kasuya, Daniel Renison, Alejandra G. BecerraAbstract:Abstract The aim of this study was to compare the arbuscular mycorrhizal fungal (AMF) community of the rhizosphere and inside the roots of the perennial Polylepis australis tree. Three forest types differing in their structural complexity due to anthropogenic disturbances were chosen at three different sites at the high mountains of central Argentina. Rhizosphere spores and P. australis roots of four randomly selected trees were isolated from 36 soil samples, DNA was extracted and the 18S rDNA fragments were amplified by nested-PCR. The products were analyzed by DGGE and the bands were excised for sequencing. In total, 36 OTUs were defined from 56 DGGE bands successfully sequenced. Forest disturbance types showed similar communities of AMF, as rhizosphere spores and within the roots of P. australis. However, DGGE clustering showed mainly differences between rhizosphere spores and root-colonizing AMF. Members of Glomeraceae, Pacisporaceae, Acaulosporaceae and Gigasporaceae were shown in rhizosphere spore samples. Root samples showed only members of Acaulosporaceae and Gigasporaceae, which might be complementary in terms of soil resources exploration. The prevalence of the root system with their community of symbionts might explain the resilience of AMF soil communities to forests structural changes. This study presents evidence of a possible preference in the AMF–P. australis interaction.
Marta Noemi Cabello - One of the best experts on this subject based on the ideXlab platform.
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Biodiversity of Arbuscular Mycorrhizal Fungi in South America: A Review
Fungal Biology, 2019Co-Authors: M. Noelia Cofré, Florencia Soteras, Marta Noemi Cabello, M. Del Rosario Iglesias, Silvana Velázquez, Camila Lucía Abarca, Lucía Risio, Emanuel Ontivero, Laura S. Domínguez, Mónica A. LugoAbstract:Arbuscular mycorrhizal fungi (AMF) are a cosmopolitan group of root symbionts associated with about 80% of earth plants. Current morphological and molecular classification describes around 300 and 1000 AMF taxa respectively. Despite the communities of AMF of many ecological divisions, biomes and ecosystems remain entirely unstudied, cumulative information has increased considerably over the last years, particularly for South America (SA). In this Chapter we reviewed the published literature of AMF morphological richness for SA in order to evaluate richness patterns across the ecological divisions of the region. The compiled data included 2187 records. The 186 morphological taxa identified in the literature evidenced an increasing interest in the study of these fungi in the region, yet with an uneven distribution among ecodivisions within the Amazonia, Atlantic forest, Caatinga and Chaco, which were the main research focus. Glomeraceae species predominated in all ecodivisions with Acaulosporaceae and Gigasporaceae alternated as the second predominant family. It is difficult to draw broad scale conclusions about richness changes among ecological divisions in SA as there are many that remain unstudied and others poorly sampled (e.g. Guianan lowlands and Patagonia respectively). Therefore, further studies of these ecosystems should be encouraged.
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Pb accumulation in spores of arbuscular mycorrhizal fungi.
The Science of the total environment, 2018Co-Authors: M. Julieta Salazar, Marta Noemi Cabello, Eugenia Menoyo, Valeria Faggioli, József Geml, Judith Hebelen Rodriguez, Nicolás Marro, Alejandro G. Pardo, M. Luisa Pignata, Alejandra C. BecerraAbstract:Abstract Heavy metal (HM) pollution of soils is one of the most important and unsolved environmental problems affecting the world, with alternative solutions currently being investigated through different approaches. Arbuscular mycorrhizal fungi (AMF) are soil inhabitants that form symbiotic relationships with plants. This alleviates HM toxicity in the host plant, thereby enhancing tolerance. However, the few investigations that have addressed the presence of metals in the fungus structures were performed under experimental conditions, with there being no results reported for Pb. The current study represents a first approximation concerning the capability of spores to accumulate Pb in the AMF community present in a Pb polluted soil under field conditions. Micro X-ray fluorescence was utilized to obtain a direct observation of Pb in spores, and the innovation of total reflection X-ray fluorescence was applied to obtain Pb quantification in spores. The AMF community included species of Ambisporaceae, Archaeosporaceae, Gigasporacea, Glomeraceae and Paraglomeraceae, and was tolerant to high Pb concentrations in soil. Pb accumulation in AMF spores was demonstrated at the community level and corroborated by direct observation of the most abundant spores, which belonged to the Gigasporaceae group. Spore Pb accumulation is possibly dependent on the AMF and host plant species.
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Elements sequestered by arbuscular mycorrhizal spores in riverine soils: A preliminary assessment
2010Co-Authors: Marcela C. Pagano, A. I. C. Persiano, Marta Noemi Cabello, Maria Rita ScottiAbstract:The elemental composition of spore wall of arbuscular mycorrhizal fungi (AMF) was analyzed by energy-dispersive X-ray spectrometry (EDS) in a preliminary assessment. Measurements of AMF spores were made for riparian soils in both urban (rivers subjected to different human activities) and farm sites in southeastern Brazil. Spore populations belonging to four genera: Acaulospora,Gigaspora, Glomus and Scutellospora were analyzed. The results suggest that Glomeraceae spores sequester more elements than Acaulosporaceae and Gigasporaceae; however, the presence of nickel was observed in oneScutellospora species. These data showed the elements sequestered by AMF spores in riparian sites presenting different conditions of disturbance. Key words: Arbuscular mycorrhizal spores, urban sites, energy-dispersive X-ray spectrometry, riparian forest.
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arbuscular mycorrhizal fungal propagules from tillage and no tillage systems possible effects on glomeromycota diversity
Mycologia, 2010Co-Authors: S Schalamuk, Marta Noemi CabelloAbstract:Arbuscular mycorrhizal fungi (AMF) can use different types of propagules to colonize new roots. In this work we tested different types of AMF inocula obtained from a field experiment with tilled and no-tilled soils planted with wheat as well as from nondisturbed treatments with spontaneous vegetation. AMF trap cultures were carried out with soil, mycelium, segments of roots and wheat plants from the field as sources of inocula. Then after the senescence of the trap plants Glomeromycota species that had been established from each type of propagule in the substrate from the pots were identified. In field soils the proportions of Acaulosporaceae and Gigasporaceae were relatively similar to that of Glomeraceae, mainly in conventional tillage, whereas in all trap cultures investigated the percentages of members of the Glomeraceae family were higher than 90%. Because most of the trap cultures were based on intra- and/or extraradical mycelium our results show that members of Glomeraceae have advantages in the use of these propagules over Acaulosporaceae and Gigasporaceae species. We suggest that the higher contribution of Glomeraceae previously found in no-tillage systems could be related partially to the lack of disruption of the hyphal network and the composition of the soil propagules in this system.
Richard J Reader - One of the best experts on this subject based on the ideXlab platform.
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Host plant benefit from association with arbuscular mycorrhizal fungi: variation due to differences in size of mycelium
Biology and Fertility of Soils, 2002Co-Authors: Miranda M. Hart, Richard J ReaderAbstract:Plants differ in the benefit they receive from an association with arbuscular mycorrhizal fungi (AMF) but it is unclear what factors determine host response. We tested whether this difference is due in part to differences among AMF families (Glomaceae, Gigasporaceae, and Acaulosporaceae) in the size of their mycelium. For example, an AMF with a large mycelium might be better able to transfer nutrients to its host. Alternatively, the large mycelium might present a large carbon drain for the host. It might also be the location of AMF mycelium that is important: whether it occurs in the root or in the soil. In a greenhouse experiment, four different host plant species were inoculated with each of 21 AMF isolates representing different mycelial sizes and we measured both host plant biomass and foliar phosphorus concentration over 12 weeks. AMF family significantly affected host biomass with larger internal mycelia conferring greater host benefit. However, both intra-family variation in AMF effect and host identity also influenced host response. For foliar P, AMF family did not affect host response significantly. Our results show that differences in mycelial size among AMF families may contribute to variation in host responsiveness to AMF, but other factors are also important.
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Does percent root length colonization and soil hyphal length reflect the extent of colonization for all AMF
Mycorrhiza, 2002Co-Authors: Miranda M. Hart, Richard J ReaderAbstract:Percent root length colonization may not be an appropriate measure of root colonization by arbuscular mycorrhizal fungi (AMF) in all cases. We suggest that AMF will differ in how well percent root length colonization measures the amount of AMF colonization in the root due to differences among AMF in hyphal structure and hyphal aggregation. Although soil hyphal length accounts for hyphal density, we suggest that it does not consider differences in hyphal structure in measurements of external colonization and thus might also misrepresent the true amount of AMF in the soil. To test these suggestions, we measured and compared percent root length colonization and soil hyphal length with root ergosterol and soil ergosterol, respectively, for 21 different species of AMF from three families in a greenhouse experiment. Percent root length colonization predicted intra-radical colonization best for Glomaceae and Acaulosporaceae isolates, while soil hyphal length best represented soil ergosterol for Gigasporaceae isolates. The results show that conventional methods for estimating AMF colonization are not universal for all AMF. Caution is advised when drawing inferences for different groups of AMF.
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Taxonomic basis for variation in the colonization strategy of arbuscular mycorrhizal fungi
New Phytologist, 2002Co-Authors: Miranda M. Hart, Richard J ReaderAbstract:Summary • Arbuscular mycorrhizal fungi (AMF) are important components of terrestrial communities but the basic ecology of individual AMF, including their colonization strategy, remains unclear. The colonizing behaviours of 21 AMF isolates from three families (Acaulosporaceae, Gigasporaceae and Glomaceae) were compared to test for a relationship between AMF taxonomy and colonization strategy. • Both the rate and extent of colonization were considered by measuring percentage root colonization, root fungal biomass, soil hyphal length and soil fungal biomass over 12 wk. • Most Glomaceae isolates colonized roots before Acaulosporaceae and Gigasporaceae isolates. The fastest colonizers were also often the most extensive. Taxonomic differences were apparent in the amount and proportion of fungal biomass found in roots vs in soil. Glomaceae isolates had high root colonization but low soil colonization, Gigasporaceae isolates showed the opposite trend whereas Acaulosporaceae isolates had low root and soil colonization. These results were similar for four different host plants. • The results indicate that the colonizing strategies of AM fungi differ considerably and that this variation is taxonomically based at the family level. Arbuscular mycorrhizal fungal taxonomy therefore has a functional basis.