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Sara F. Wright - One of the best experts on this subject based on the ideXlab platform.
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terrestrial marine connectivity patterns of terrestrial soil carbon deposition in coastal sediments determined by analysis of Glomalin related soil protein
Limnology and Oceanography, 2012Co-Authors: Sara F. Wright, Maria Fernanda Adame, Alistair Grinham, Kellie Lobb, Claire E Reymond, Catherine E LovelockAbstract:Glomalin, an arbuscular mycorrhizal protein component of soil, can be used as an indicator of terrigenousderived carbon. We measured Glomalin in sediments using the terrestrial end-member as a reference in four coastal settings: (1) intertidal seagrass meadows distributed over a rainfall gradient, (2) sediments inshore and offshore from the mouth of a river, (3) coastal coral reefs at various distances from the shore, and (4) intertidal wetlands with varying levels of groundwater influence. Across the rainfall gradient, Glomalin in seagrass meadow sediments increased at sites with high mean annual rainfall during the wet season (r2 5 0.27; F1,29 5 5.75; p 5 0.029). Glomalin decreased in inshore river sediments (terrestrial) to offshore (marine) sediments (r2 5 0.81; F1,17 5 71.7; p # 0.0001). Furthermore, Glomalin in reef sediments decreased with distance from the shore. The high intertidal was rich in Glomalin where groundwater flowed directly into the wetland compared with those with little groundwater influences. Our data indicate that rivers and groundwater transport terrestrial material, and that mangroves, salt marsh, seagrass meadows, and coral reefs accumulate it, but the connections vary among sites, within sites, and seasonally. Variations in Glomalin concentrations are indicative of links between the terrestrial and marine environment that reflect proximity, filtration services, and the level of subsidies that marine ecosystems derive from terrestrial sources. Assessment of Glomalin contributes to evaluating terrestrial–marine connectivity, and thus provides knowledge to improve catchment management for the protection of marine ecosystems.
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Disturbance changes arbuscular mycorrhizal fungal phenology and soil Glomalin concentrations but not fungal spore composition in montane rainforests in Veracruz and Chiapas, Mexico
Forest Ecology and Management, 2008Co-Authors: Helen A. Violi, Sara F. Wright, Alejandro F. Barrientos-priego, Esteban Escamilla-prado, Joseph B. Morton, John A. Menge, Carol J. LovattAbstract:Mexican montane rainforests and adjacent disturbed areas were studied for disturbance-related spatio-temporal changes to the arbuscular mycorrhizal fungal (AMF) community and soil Glomalin concentration. The AMF community functions to both improve plant growth and soil conditions and is thus an important component to the restoration of this forest type to disturbed areas. The study areas included mature rainforests that were converted to pine forests, milpas, pastures and shrub/herbaceous plant communities via burning and logging. Seasonal patterns in AMF spore species richness and sporulation significantly differed across disturbance types at two of the three sites surveyed. Contrasting patterns of sporulation among AMF families across different disturbance types helped to explain how species richness and composition were maintained despite dramatic changes to the host plant community. Meaning, in most cases, disturbance induced changes in when different AMF taxa sporulated but not what taxa sporulated. Only conversion from mature pine‐oak‐Liquidambar‐Persea forests to pine-dominated stands severely reduced AMF spore richness and total sporulation. Surprisingly, in pine-dominant stands no concomitant negative impacts on soil Glomalin (MAb32B11 immunoreactive soil protein) concentrations were detected. However, soils of mature forests containing no pines had the highest concentration of Glomalin. Conversion to pasture and milpa (diverse cornfield) had a strong negative impact on the concentration of soil Glomalin concentrations. In sharp contrast, the same disturbance types improved AMF sporulation and AMF spore richness. It appears that disturbance type, and not AMF community measures used herein, best predicts changes in soil Glomalin concentration. # 2007 Elsevier B.V. All rights reserved.
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Comparison of efficacy of three extractants to solubilize Glomalin on hyphae and in soil
Chemosphere, 2006Co-Authors: Sara F. Wright, Kristine A Nichols, Walter F. SchmidtAbstract:Glomalin, a glycoprotein produced by arbuscular mycorrhizal (AM) fungi, is a major component of the humus fraction of soil organic matter. Glomalin is extracted from soil and hyphae of AM fungi by using sodium citrate at 121 degrees C in multiple 1-h cycles, but extensive extraction does not solubilize all Glomalin in all soils. Efficacies of 100 mM sodium salts of citrate, borate or pyrophosphate (pH 9.0, 121 degrees C) were tested for two 1-h cycles for hyphae from four AM fungal isolates and four 1-h cycles for seven soils from four US geographic regions. Residual soil Glomalin was examined by pyrophosphate extraction of soils previously extracted with citrate or borate followed by extraction of all soils after treatment with NaOH. Hyphal extracts were compared using Bradford-reactive total protein (BRTP) values, and extracts from soils were compared using BRTP, percentage C and C weight. No difference among extractants was detected for AM fungal isolates or across soils. The residual Glomalin across soils for extractants contained the following percentages of the total BRTP: pyrophosphate, 14%; borate, 17%; and citrate, 22%. Comparisons among individual soils indicated that pyrophosphate extracted significantly more BRTP (10-53%) than borate or citrate in six soils and borate was equal to pyrophosphate in one soil. Extraction with borate should be compared with pyrophosphate before initiating an experiment. For routine extractions of ca. 85% of the Glomalin across a variety of soils, sodium pyrophosphate appears to be equal to or better than borate and better than citrate.
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the role of Glomalin a protein produced by arbuscular mycorrhizal fungi in sequestering potentially toxic elements
Environmental Pollution, 2004Co-Authors: M C Gonzalezchavez, Sara F. Wright, R Carrillogonzalez, Kristine A NicholsAbstract:Naturally occurring soil organic compounds stabilize potentially toxic elements (PTEs) such as Cu, Cd, Pb, and Mn. The hypothesis of this work was that an insoluble glycoprotein, Glomalin, produced in copious amounts on hyphae of arbuscular mycorrhizal fungi (AMF) sequesters PTEs. Glomalin can be extracted from laboratory cultures of AMF and from soils. Three different experiments were conducted. Experiment 1 showed that Glomalin extracted from two polluted soils contained 1.6–4.3 mg Cu, 0.02–0.08 mg Cd, and 0.62–1.12 mg Pb/g Glomalin. Experiment 2 showed that Glomalin from hyphae of an isolate of Gigaspora rosea sequestered up to 28 mg Cu/g in vitro. Experiment 3 tested in vivo differences in Cu sequestration by Cu-tolerant and non-tolerant isolates of Glomus mosseae colonizing sorghum. Plants were fed with nutrient solution containing 0.5, 10 or 20 μM of Cu. Although no differences between isolates were detected, mean values for the 20 μM Cu level were 1.6, 0.4, and 0.3 mg Cu/g for Glomalin extracted from hyphae, from sand after removal of hyphae and from hyphae attached to roots, respectively. Glomalin should be considered for biostabilization leading to remediation of polluted soils.
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using Glomalin as an indicator for arbuscular mycorrhizal hyphal growth an example from a tropical rain forest soil
Soil Biology & Biochemistry, 2004Co-Authors: Catherine E Lovelock, Sara F. Wright, Kristine NicholsAbstract:Glomalin concentrations of extra-radical arbuscular mycorrhizal (AM) hyphae were estimated by deploying hyphal in-growth cores ;containing Glomalin-free sand in field soils in a tropical forest and in pot cultures. In field soils, Glomalin was 0.044 +/- 0.013 mug m(-1) hyphae. In pot cultures Glomalin concentrations were lower (range 0.0068-0.036 mug m(-1)), and varied significantly among species. Using this technique, preliminary estimates of extraradical AM hyphal production on Inceptisols were 1.91 Mg ha(-1) yr(-1) and on Oxisol were 1.47 Mg ha(-1) yr(-1), but they could range between 0.9-5.7 Mg ha(-1) yr(-1). These rates of hyphal production are approximately 10% (range 5-33%) of estimated above ground primary production of the forest. (C) 2004 Elsevier Ltd. All rights reserved.
Matthias C. Rillig - One of the best experts on this subject based on the ideXlab platform.
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The influence of different stresses on Glomalin levels in an arbuscular mycorrhizal fungus--salinity increases Glomalin content.
PloS one, 2011Co-Authors: Edith C. Hammer, Matthias C. RilligAbstract:Glomalin is a glycoprotein produced by arbuscular mycorrhizal (AM) fungi, and the soil fraction containing Glomalin is correlated with soil aggregation. Thus, factors potentially influencing Glomalin production could be of relevance for this ecosystem process and for understanding AM fungal physiology. Previous work indicated that Glomalin production in AM fungi may be a stress response, or related to suboptimal mycelium growth. We show here that environmental stress can enhance Glomalin production in the mycelium of the AM fungus Glomus intraradices. We applied NaCl and glycerol in different intensities to the medium in which the fungus was grown in vitro, causing salinity stress and osmotic stress, respectively. As a third stress type, we simulated grazing on the extraradical hyphae of the fungus by mechanically injuring the mycelium by clipping. NaCl caused a strong increase, while the clipping treatment led to a marginally significant increase in Glomalin production. Even though salinity stress includes osmotic stress, we found substantially different responses in Glomalin production due to the NaCl and the glycerol treatment, as glycerol addition did not cause any response. Thus, our results indicate that Glomalin is involved in inducible stress responses in AM fungi for salinity, and possibly grazing stress.
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Immuno-cytolocalization of Glomalin in the mycelium of the arbuscular mycorrhizal fungus Glomus intraradices
Soil Biology and Biochemistry, 2008Co-Authors: Sonia Purin, Matthias C. RilligAbstract:A better understanding of the role of Glomalin in arbuscular mycorrhizal fungi necessitates knowledge about the cellular functions and locations of this putative heat-shock protein (Hsp). In the present study, we determined the cellular localization of Glomalin in mycelium of Glomus intraradices using immuno-electron microscopy, employing the monoclonal antibody MAb32B11. We observed that there were more gold beads bound to hyphae and spore walls than in the cytoplasm. There was also differential binding within the wall layers: L3 and L2 presented more intense labeling than the L1 layer. Our data on wall-binding of Glomalin are strongly suggestive of functions other than cytoplasmic (Hsp-related), and point to a possibility of mediating interactions with the biotic and abiotic soil environment.
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the arbuscular mycorrhizal fungal protein Glomalin limitations progress and a new hypothesis for its function
Pedobiologia, 2007Co-Authors: Sonia Purin, Matthias C. RilligAbstract:Summary Most research on Glomalin-related soil proteins (GRSP) has focused on the role of arbuscular mycorrhizal fungi in soil aggregation and environmental engineering. Recently, with the description of the Glomalin gene sequence and other results, work on this protein has shifted to include fungal physiology. Based on recent findings, we develop a new model for the role of Glomalin; we postulate a primary role in fungal physiology and secondarily arising effects in the soil environment that lead to observed correlations of GRSP with soil aggregate stability. Concurrent with advances in molecular biology, several recent studies have highlighted problems with quantifying GRSP from soil. We summarize and discuss limitations of the methods currently used for GRSP extraction and quantification in soils. We finish with a set of recommendations for research directions that involve testing the model proposed here.
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the arbuscular mycorrhizal fungal protein Glomalin is a putative homolog of heat shock protein 60
Fems Microbiology Letters, 2006Co-Authors: Vijay Gadkar, Matthias C. RilligAbstract:Work on Glomalin-related soil protein produced by arbuscular mycorrhizal (AM) fungi (AMF) has been limited because of the unknown identity of the protein. A protein band cross-reactive with the Glomalin-specific antibody MAb32B11 from the AM fungus Glomus intraradices was partially sequenced using tandem liquid chromatography-mass spectrometry. A 17 amino acid sequence showing similarity to heat shock protein 60 (hsp 60) was obtained. Based on degenerate PCR, a full-length cDNA of 1773 bp length encoding the hsp 60 gene was isolated from a G. intraradices cDNA library. The ORF was predicted to encode a protein of 590 amino acids. The protein sequence had three N-terminal glycosylation sites and a string of GGM motifs at the C-terminal end. The GiHsp 60 ORF had three introns of 67, 76 and 131 bp length. The GiHsp 60 was expressed using an in vitro translation system, and the protein was purified using the 6xHis-tag system. A dot-blot assay on the purified protein showed that it was highly cross-reactive with the Glomalin-specific antibody MAb32B11. The present work provides the first evidence for the identity of the Glomalin protein in the model AMF G. intraradices, thus facilitating further characterization of this protein, which is of great interest in soil ecology.
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characterization of Glomalin as a hyphal wall component of arbuscular mycorrhizal fungi
Soil Biology & Biochemistry, 2005Co-Authors: James D Driver, William E Holben, Matthias C. RilligAbstract:Abstract Arbuscular mycorrhizal fungi (AMF) produce a protein, Glomalin, quantified operationally in soils as Glomalin-related soil protein (GRSP). GRSP concentrations in soil can range as high as several mg g−1 soil, and GRSP is highly positively correlated with aggregate water stability. Given that AMF are obligate biotrophs (i.e. depending on host cells for their C supply), it is difficult to explain why apparently large amounts of Glomalin would be produced and secreted actively into the soil, since the carbon could not be directly recaptured by the mycelium (and benefits to the AMF via increased soil structure would be diffuse and indirect). This apparent contradiction could be resolved by learning more about the pathway of delivery of Glomalin into soil; namely, does this occur via secretion, or is Glomalin tightly bound in the fungal walls and only released after hyphae are being degraded by the soil microbial community? In order to address this question, we grew the AMF Glomus intraradices in in vitro cultures and studied the release of Glomalin from the mycelium and the accumulation of Glomalin in the culture medium. Numerous protein-solubilizing treatments to release Glomalin from the fungal mycelium were unsuccessful (including detergents, acid, base, solvents, and chaotropic agents), and the degree of harshness required to release the compound (autoclaving, enzymatic digestion) is consistent with the hypothesis that Glomalin is tightly bound in hyphal and spore walls. Further, about 80% of Glomalin (by weight) produced by the fungus was contained in hyphae and spores compared to that released into the culture medium, strongly suggesting that Glomalin arrives mainly in soil via release from hyphae, and not primarily through secretion. These results point research on functions of Glomalin and GRSP in a new direction, focusing on the contributions this protein makes to the living mycelium, rather than its role once it is released into the soil.
Catherine E Lovelock - One of the best experts on this subject based on the ideXlab platform.
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terrestrial marine connectivity patterns of terrestrial soil carbon deposition in coastal sediments determined by analysis of Glomalin related soil protein
Limnology and Oceanography, 2012Co-Authors: Sara F. Wright, Maria Fernanda Adame, Alistair Grinham, Kellie Lobb, Claire E Reymond, Catherine E LovelockAbstract:Glomalin, an arbuscular mycorrhizal protein component of soil, can be used as an indicator of terrigenousderived carbon. We measured Glomalin in sediments using the terrestrial end-member as a reference in four coastal settings: (1) intertidal seagrass meadows distributed over a rainfall gradient, (2) sediments inshore and offshore from the mouth of a river, (3) coastal coral reefs at various distances from the shore, and (4) intertidal wetlands with varying levels of groundwater influence. Across the rainfall gradient, Glomalin in seagrass meadow sediments increased at sites with high mean annual rainfall during the wet season (r2 5 0.27; F1,29 5 5.75; p 5 0.029). Glomalin decreased in inshore river sediments (terrestrial) to offshore (marine) sediments (r2 5 0.81; F1,17 5 71.7; p # 0.0001). Furthermore, Glomalin in reef sediments decreased with distance from the shore. The high intertidal was rich in Glomalin where groundwater flowed directly into the wetland compared with those with little groundwater influences. Our data indicate that rivers and groundwater transport terrestrial material, and that mangroves, salt marsh, seagrass meadows, and coral reefs accumulate it, but the connections vary among sites, within sites, and seasonally. Variations in Glomalin concentrations are indicative of links between the terrestrial and marine environment that reflect proximity, filtration services, and the level of subsidies that marine ecosystems derive from terrestrial sources. Assessment of Glomalin contributes to evaluating terrestrial–marine connectivity, and thus provides knowledge to improve catchment management for the protection of marine ecosystems.
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using Glomalin as an indicator for arbuscular mycorrhizal hyphal growth an example from a tropical rain forest soil
Soil Biology & Biochemistry, 2004Co-Authors: Catherine E Lovelock, Sara F. Wright, Kristine NicholsAbstract:Glomalin concentrations of extra-radical arbuscular mycorrhizal (AM) hyphae were estimated by deploying hyphal in-growth cores ;containing Glomalin-free sand in field soils in a tropical forest and in pot cultures. In field soils, Glomalin was 0.044 +/- 0.013 mug m(-1) hyphae. In pot cultures Glomalin concentrations were lower (range 0.0068-0.036 mug m(-1)), and varied significantly among species. Using this technique, preliminary estimates of extraradical AM hyphal production on Inceptisols were 1.91 Mg ha(-1) yr(-1) and on Oxisol were 1.47 Mg ha(-1) yr(-1), but they could range between 0.9-5.7 Mg ha(-1) yr(-1). These rates of hyphal production are approximately 10% (range 5-33%) of estimated above ground primary production of the forest. (C) 2004 Elsevier Ltd. All rights reserved.
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soil stocks of Glomalin produced by arbuscular mycorrhizal fungi across a tropical rain forest landscape
Journal of Ecology, 2004Co-Authors: Catherine E Lovelock, Sara F. Wright, Deborah A. Clark, Roger W RuessAbstract:1 Symbiotic arbuscular mycorrhizal (AM) fungi produce a recalcitrant AM-specific glycoprotein, Glomalin, which could be a substantial contributor to soil carbon (C). In this study we made a first assessment of the standing stocks of Glomalin in a tropical lowland rain forest (the La Selva Biological Station, Costa Rica) and tested whether Glomalin concentrations varied over the strong fertility gradient in this forest. 2 Mean levels of Glomalin in the top 10 cm of the La Selva soils were 3.94 +/- 0.16 mg cm(-3) (1.45 Mg C ha(-1)), accounting for approximately 3.2% of total soil C and 5% of soil nitrogen (N) in the 0-10 cm soil layer. 3 More fertile soils with higher concentrations of calcium, phosphorus and potassium had less Glomalin, while the less fertile soils, those with high C : N ratios and high levels of iron and aluminium, had more Glomalin. 4 We found higher levels of immunoreactivity, which is characteristic of young, recently produced Glomalin, in the soils with higher concentrations of calcium, phosphorus and potassium. We hypothesize that AM fungal turnover, as indicated by a greater proportion of immunoreactive, recently produced Glomalin, is enhanced in the more fertile soils within this tropical rain forest landscape.
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Short communication Using Glomalin as an indicator for arbuscular mycorrhizal hyphal growth: an example from a tropical rain forest soil
2004Co-Authors: Catherine E Lovelock, Sara F. Wright, Kristine A NicholsAbstract:Glomalin concentrations of extra-radical arbuscular mycorrhizal (AM) hyphae were estimated by deploying hyphal in-growth cores containing Glomalin-free sand in field soils in a tropical forest and in pot cultures. In field soils, Glomalin was 0.044 ^ 0.013 m gm 21 hyphae. In pot cultures Glomalin concentrations were lower (range 0.0068 ‐ 0.036 m gm 21 ), and varied significantly among species. Using this technique, preliminary estimates of extraradical AM hyphal production on Inceptisols were 1.91 Mg ha 21 yr 21 and on Oxisol were 1.47 Mg ha 21 yr 21 , but they could range between 0.9 ‐5.7 Mg ha 21 yr 21 . These rates of hyphal production are approximately 10% (range
Wenjie Wang - One of the best experts on this subject based on the ideXlab platform.
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Glomalin changes in urban rural gradients and their possible associations with forest characteristics and soil properties in harbin city northeastern china
Journal of Environmental Management, 2018Co-Authors: Wenjie Wang, Qiong A Wang, Wei Zhou, Lu Xiao, Huimei WangAbstract:Glomalin-related soil protein (GRSP) is a glycoprotein from the hyphae and spores of arbuscular mycorrhizal fungi. Despite urbanization being the leading cause of present-day land-use changes, there is limited information available on the effects of urbanization on GRSP. We sampled soil from 257 plots in Harbin City, China, and surveyed forest characteristics, soil properties, and urbanization gradients related to ring road development, urban history, and land use. Two Glomalin components (easily extracted Glomalin, EEG; and total Glomalin, TG) and their relative contributions to soil organic carbon (SOC: EEG/SOC, TG/SOC) were measured in the laboratory. We found exponential increases in EEG/SOC and TG/SOC from the most urbanized to the most rural regions, indicating that urbanization sharply reduced Glomalin-related SOC sequestration. In general, 1.3-1.4-fold higher Glomalin levels were found in the newly urbanized, previously rural areas, while Glomalin contribution to SOC sequestration was lower by 38-59% for EEG and 74-85% for TG in the most urbanized regions compared to rural regions. Accompanying these recorded changes in Glomalin, linear decreases in soil pH and electrical conductance were observed in all three urban-rural gradients from the urban center to the rural area, and steep decreases in conifer ratio and shrub richness were seen in two of the gradients. The complex associations among Glomalin and forest characteristics, soil properties, and urbanization gradients were decoupled and cross-checked using redundancy analysis variation partitioning and structural equation model analysis. Urbanization indirectly changed Glomalin features by altering soil properties, with soil properties accounting for over 60% of the Glomalin variation. Forest characteristics and urbanization gradients contributed to 10-15% of the Glomalin variation. With rapid urbanization occurring in China and on a global scale, Glomalin variation should be considered when evaluating soil carbon sequestration and in developing effective forest management strategies, with the aim of ameliorating soil degradation in urbanized regions by rehabilitating Glomalin accumulation.
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Glomalin contributed more to carbon, nutrients in deeper soils, and differently associated with climates and soil properties in vertical profiles
Scientific reports, 2017Co-Authors: Wenjie Wang, Zhaoliang Zhong, Qiong Wang, Humei WangAbstract:Despite vital importance in soil conditioning and a proxy for arbuscular mycorrhizal (AMF), Glomalin-related soil protein (GRSP) contribution to soil carbon and nutrients at vertical soil profiles and underlying mechanism were not well-defined yet. Thus, 360 soil samples were collected from 72 farmland 1-m soil profiles in northeastern China, and soil physiochemical properties, nutrients, Glomalin characteristics, local climates were determined. Linear decreases of Glomalin amounts were observed from the top to deep soils, and Glomalin/SOC (Glomalin ratio to total SOC) in the 80–100 cm soil (EEG, easily-extracted GRSP, 2.2%; TG, total GRSP, 19%) was 1.34–1.5-fold higher than did in the 0–20 cm soil. Different statistical analyses crosschecked that the lower pH and higher SOC usually accompanied with the higher EEG and TG, while EEG was more sensitive to climates; Moreover, Glomalin was more physiochemical-regulated in the deep soils, but more nutrient-regulation was found in the surface soils. Structure Equation Model showed that soil depths and climates indirectly affected TG and EEG features through soil properties, except significant direct effects on EEG. In future, Glomalin assessment should fully consider these for identifying the AMF importance in the whole 1-m profile, and our findings also favor degrade soil improvement from Glomalin rehabilitation.
Kristine A Nichols - One of the best experts on this subject based on the ideXlab platform.
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Comparison of efficacy of three extractants to solubilize Glomalin on hyphae and in soil
Chemosphere, 2006Co-Authors: Sara F. Wright, Kristine A Nichols, Walter F. SchmidtAbstract:Glomalin, a glycoprotein produced by arbuscular mycorrhizal (AM) fungi, is a major component of the humus fraction of soil organic matter. Glomalin is extracted from soil and hyphae of AM fungi by using sodium citrate at 121 degrees C in multiple 1-h cycles, but extensive extraction does not solubilize all Glomalin in all soils. Efficacies of 100 mM sodium salts of citrate, borate or pyrophosphate (pH 9.0, 121 degrees C) were tested for two 1-h cycles for hyphae from four AM fungal isolates and four 1-h cycles for seven soils from four US geographic regions. Residual soil Glomalin was examined by pyrophosphate extraction of soils previously extracted with citrate or borate followed by extraction of all soils after treatment with NaOH. Hyphal extracts were compared using Bradford-reactive total protein (BRTP) values, and extracts from soils were compared using BRTP, percentage C and C weight. No difference among extractants was detected for AM fungal isolates or across soils. The residual Glomalin across soils for extractants contained the following percentages of the total BRTP: pyrophosphate, 14%; borate, 17%; and citrate, 22%. Comparisons among individual soils indicated that pyrophosphate extracted significantly more BRTP (10-53%) than borate or citrate in six soils and borate was equal to pyrophosphate in one soil. Extraction with borate should be compared with pyrophosphate before initiating an experiment. For routine extractions of ca. 85% of the Glomalin across a variety of soils, sodium pyrophosphate appears to be equal to or better than borate and better than citrate.
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the role of Glomalin a protein produced by arbuscular mycorrhizal fungi in sequestering potentially toxic elements
Environmental Pollution, 2004Co-Authors: M C Gonzalezchavez, Sara F. Wright, R Carrillogonzalez, Kristine A NicholsAbstract:Naturally occurring soil organic compounds stabilize potentially toxic elements (PTEs) such as Cu, Cd, Pb, and Mn. The hypothesis of this work was that an insoluble glycoprotein, Glomalin, produced in copious amounts on hyphae of arbuscular mycorrhizal fungi (AMF) sequesters PTEs. Glomalin can be extracted from laboratory cultures of AMF and from soils. Three different experiments were conducted. Experiment 1 showed that Glomalin extracted from two polluted soils contained 1.6–4.3 mg Cu, 0.02–0.08 mg Cd, and 0.62–1.12 mg Pb/g Glomalin. Experiment 2 showed that Glomalin from hyphae of an isolate of Gigaspora rosea sequestered up to 28 mg Cu/g in vitro. Experiment 3 tested in vivo differences in Cu sequestration by Cu-tolerant and non-tolerant isolates of Glomus mosseae colonizing sorghum. Plants were fed with nutrient solution containing 0.5, 10 or 20 μM of Cu. Although no differences between isolates were detected, mean values for the 20 μM Cu level were 1.6, 0.4, and 0.3 mg Cu/g for Glomalin extracted from hyphae, from sand after removal of hyphae and from hyphae attached to roots, respectively. Glomalin should be considered for biostabilization leading to remediation of polluted soils.
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Short communication Using Glomalin as an indicator for arbuscular mycorrhizal hyphal growth: an example from a tropical rain forest soil
2004Co-Authors: Catherine E Lovelock, Sara F. Wright, Kristine A NicholsAbstract:Glomalin concentrations of extra-radical arbuscular mycorrhizal (AM) hyphae were estimated by deploying hyphal in-growth cores containing Glomalin-free sand in field soils in a tropical forest and in pot cultures. In field soils, Glomalin was 0.044 ^ 0.013 m gm 21 hyphae. In pot cultures Glomalin concentrations were lower (range 0.0068 ‐ 0.036 m gm 21 ), and varied significantly among species. Using this technique, preliminary estimates of extraradical AM hyphal production on Inceptisols were 1.91 Mg ha 21 yr 21 and on Oxisol were 1.47 Mg ha 21 yr 21 , but they could range between 0.9 ‐5.7 Mg ha 21 yr 21 . These rates of hyphal production are approximately 10% (range
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Large contribution of arbuscular mycorrhizal fungi to soil carbon pools in tropical forest soils
Plant and Soil, 2001Co-Authors: Matthias C. Rillig, Sara F. Wright, Kristine A Nichols, Walter F. Schmidt, Margaret S. TornAbstract:The origins and composition of soil organic matter (SOM) are still largely uncertain. Arbuscular mycorrhizal fungi (AMF) are recognized as indirect contributors through their influence on soil aggregation, plant physiology, and plant community composition. Here we present evidence that AMF can also make large, direct contributions to SOM. Glomalin, a recently discovered glycoprotein produced by AMF hyphae, was detected in tropical soils in concentrations of over 60 mg cm^−3. Along a chronosequence of soils spanning ages from 300 to 4.1 Mio years, a pattern of Glomalin concentrations is consistent with the hypothesis that this protein accumulates in soil. Carbon dating of Glomalin indicated turnover at time scales of several years to decades, much longer than the turnover of AMF hyphae (which is assumed to be on the order of days to weeks). This suggests that contributions of mycorrhizae to soil carbon storage based on hyphal biomass in soil and roots may be an underestimate. The amount of C and N in Glomalin represented a sizeable amount (ca. 4–5%) of total soil C and N in the oldest soils. Our results thus indicate that microbial (fungal) carbon that is not derived from above- or below-ground litter can make a significant contribution to soil carbon and nitrogen pools and can far exceed the contributions of soil microbial biomass (ranging from 0.08 to 0.2% of total C for the oldest soils).