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1
Valdes, María. "Aspectos ecofisiológicos de las micorrizas." Botanical Sciences, no. 49 (April 10, 2017): 19. http://dx.doi.org/10.17129/botsci.1363.
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Mycorrhiza is the part of the roots infected with particular soil fungi. This type of association is formed by most of the plants. There are several types of mycorrhizae; this short review is concerned only with Ectomycorrhiza (EM) and the Vesicular-Arbuscular Mycorrhiza (VAM). These two types are the most common in nature. EM has a compact fungus mantle over the root surface and intercellular hypha in the cortex; the V AM has a loose network of hyphae in the soil surrounding the root and hyphal growth within the cortical cells. Mycorrhizas increase nutrient uptake and hence plant growth. Since mycorrhizas are surrounded by an extensive hyphal network than may extcnd into the soil, this network represents a greater surface area, in other words, mycorrhizas shorten the distance that nutrients must diffuse through the soil to the root and their hyphae increase the volume of soil available to the plant for nutrient uptake. Physiological responses to root colonization with mycorrhizal fungi by most of the plants are dependent on the level of soil fertility and on the degree of mycorrhizal dependency of the plant. Soils having a high fertility have mostly a poor colonization, hence, for plant growth to respond to inoculation, soils must have a low fertility. Mycorrhizal dependency can be very different among plant species; plants with short root hairs are more dependent on mycorrhizal fungi. Most soils contain mycorrhizal fungi and their distribution varies with climatic, edaphic environment and land use. There are differences in effectiveness in colonization and in enhanced nutrient uptake among the fungi.
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Schroeder-Moreno, Michelle S., and David P. Janos. "Intra- and inter-specific density affects plant growth responses to arbuscular mycorrhizas." Botany 86, no. 10 (October 2008): 1180–93. http://dx.doi.org/10.1139/b08-080.
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Arbuscular mycorrhizas can alter competitive interactions between plants that markedly differ in their dependence upon mycorrhizas, but little is known about how mycorrhizas affect intra- and inter-specific competition between similarly dependent plant species. We conducted competition experiments in pots between all pairs of the similarly facultatively mycotrophic crop species, chili ( Capsicum annuum L.), maize ( Zea mays L.), and zucchini ( Cucurbita pepo L.). We used a two-species yield-density model to analyze the separate effects of mycorrhizal inoculation, intra-, and inter-specific density on biomass responses. Mycorrhizas reduced the growth of all three plant species. Intraspecific competition increased the negative effect of mycorrhizas, as did interspecific competition at low intraspecific density. At high intraspecific density, however, interspecific competition improved plant responsiveness to mycorrhizas. Enhancement of plant benefit from mycorrhizas at high interspecific density of competing, weakly mycorrhiza-dependent species may help to explain the evolutionary maintenance of their associations with mycorrhizal fungi, and may be a key to understanding intercrop combinations that exceed the monoculture yields of component species.
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Jones, Melanie D., and Sally E. Smith. "Exploring functional definitions of mycorrhizas: Are mycorrhizas always mutualisms?" Canadian Journal of Botany 82, no. 8 (August 1, 2004): 1089–109. http://dx.doi.org/10.1139/b04-110.
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Mycorrhizas are considered to be classic mutualisms. Here, we define mutualism as a reciprocal increase in fitness of the symbionts, and we review the evidence for mycorrhizal mutualism at the community, whole-plant, and cellular scales. It is difficult to use results of most mycorrhizal studies because (i) fungal contribution to nutrient uptake is not accurately estimated, (ii) increased growth is not necessarily correlated with increased plant fecundity or survival, especially in communities, and (iii) benefits that occur only at certain times of year, or under specific extreme conditions, may not be detected. To produce the nonmycorrhizal controls required to study mutualism in the field, soil microflora and fauna must be severely perturbed; therefore, it is virtually impossible to evaluate effects of mycorrhizas on plant fitness under realistic conditions. Using the evidence available, we conclude that mycorrhizas can occupy various positions along the continuum from parasitism to mutualism, depending on the specific plant and fungal genotypes and their abiotic and biotic environments. Although we discuss the possibility of defining mycorrhizas by some physiological characteristic, we conclude that mycorrhizas should be defined on a structural or developmental basis and that any requirement to demonstrate mutualism be eliminated.Key words: mycorrhiza, mutualism, parasitism, physiology, fitness, community.
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Allsopp, N., and W. D. Stock. "Plant Protection Research Institute." Bothalia 23, no. 1 (October 10, 1993): 91–104. http://dx.doi.org/10.4102/abc.v23i1.794.
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A survey of the mycorrhizal status of plants growing in the Cape Floristic Region of South Africa was undertaken to assess the range of mycorrhizal types and their dominance in species characteristic of this region. Records were obtained by examining the root systems of plants growing in three Cape lowland vegetation types, viz. West Coast Strandveld, West Coast Renosterveld and Sand Plain Lowland Fynbos for mycorrhizas, as well as by collating literature records of mycorrhizas on plants growing in the region. The mycorrhizal status of 332 species is listed, of which 251 species are new records. Members of all the important families in this region have been examined. Mycorrhizal status appears to be associated mainly with taxonomic position of the species. Extrapolating from these results, we conclude that 62% of the flora of the Cape Floristic Region form vesicular-arbuscular mycorrhizas, 23% have no mycorrhizas, 8% are ericoid mycorrhizal, 2% form orchid mycorrhizas, whereas the mycorrhizal status of 4% of the flora is unknown. There were no indigenous ectomycor- rhizal species. The proportion of non-mycorrhizal species is high compared to other ecosystems. In particular, the lack of mycorrhizas in several important perennial families in the Cape Floristic Region is unusual. The diversity of nutrient acquiring adaptations, including the range of mycorrhizas and cluster roots in some non-mycorrhizal families, may promote coexistence of plants in this species-rich region.
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Turnau, Katarzyna, Piotr Mleczko, Damien Blaudez, Michel Chalot, and Bernard Botton. "Heavy metal binding properties of Pinus sylvestris mycorrhizas from industrial wastes." Acta Societatis Botanicorum Poloniae 71, no. 3 (2014): 253–61. http://dx.doi.org/10.5586/asbp.2002.030.
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Mycorrhizas of <em>Pinus sylvestris</em>, collected from zinc wastes in Poland and France were investigated using transmission electron microscope (TEM) and scanning electron microscope (SEM) equipped with energy dispersion spectroscopy (EDS) and electron energy loss spectroscopy (EELS). At both sites, mycorrhizas of <em>Hebeloma</em> were the most frequent, however, they were often characterised by a sparse or only locally developed fungal mantle. Mycorrhizas formed by suilloid fungi were much less frequent, and usually produced a clearly defined fungal mantle characterised by abundant formation of pigments and crystals covering the hyphae of the outer mantle. These two groups of mycorrhizas differed in their heavy metal binding properties. A biofiltering effect of Pb and Zn by the fungal mantle was observed only in the case of suilloid mycorrhizas, which represented up to 10% of the total number of mycorrhizas. No statistical differences between the mantle, the cortical cell walls and the vascular tissue were demonstrated in mycorrhizas formed by other fungi dominating on industrial wastes. In the case of <em>Hebeloma</em> and <em>Inocybe</em>, however, elements such as Cu and Cd were present in higher amounts in the extra-matrical mycelium, whereas no or only low amounts of these elements were detected within fungal mantles, mainly in mycorrhizas from the French waste. Analysis of the root systems has shown relatively high percentage of nonmycorrhizal short roots, suggesting the inhibition of mycorrhiza formation or a decreased number of mycorrhizal propagules. The role of dead roots and mycorrhizas in biosorption and immobilization of heavy metals was discussed.
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Adams, Felicity, Paul Reddell, Michael J. Webb, and Warren A. Shipton. "Arbuscular mycorrhizas and ectomycorrhizas on Eucalyptus grandis (Myrtaceae) trees and seedlings in native forests of tropical north-eastern Australia." Australian Journal of Botany 54, no. 3 (2006): 271. http://dx.doi.org/10.1071/bt05028.
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Eucalypts have been shown to form both arbuscular mycorrhizas (AM) and ectomycorrhizas (ECM) in glasshouse experiments. Little is known, however, about the relative dominance of these two mycorrhiza types on individual eucalypt species across their natural range. This study examined mycorrhizal colonisation levels of Eucalyptus grandis Hill ex Maiden roots at 29 sites representing a broad range of wet sclerophyll forest types in the wet tropics of north-eastern Australia. Adult E. grandis trees sampled in situ were invariably heavily ectomycorrhizal, with 76–100% fine root length colonised (% RLC). There were comparatively low levels of AM, with typically less than 10% RLC. Seedling E. grandis grown in intact soil cores from the field sites under glasshouse conditions had lower total levels of mycorrhiza formation compared with adult trees, with more variable ECM formation (10–95% RLC) and more extensive AM formation (10–40% RLC). There were no apparent trends in mycorrhiza formation across different soil parent material, rainfall or vegetation categories used. The current research suggests that arbuscular mycorrhizas are more prominent on seedlings, whereas ectomycorrhizas predominate in adult trees of E. grandis. Possible reasons for these differences and a comparison with other studies of eucalypt mycorrhizas under natural conditions are presented.
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Tammi, Hanna, Sari Timonen, and Robin Sen. "Spatiotemporal colonization of Scots pine roots by introduced and indigenous ectomycorrhizal fungi in forest humus and nursery Sphagnum peat microcosms." Canadian Journal of Forest Research 31, no. 5 (May 1, 2001): 746–56. http://dx.doi.org/10.1139/x01-011.
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Mycorrhizal and non-mycorrhizal Scots pine (Pinus sylvestris L.) seedling combinations were grown in two-dimensional Perspex® microcosms containing forest humus or nursery Sphagnum peat, without additional fertilization. Spatial and temporal patterns of mycorrhizal fungal colonization of roots were assessed over a 3-month period, through visual morphotyping and polymerase chain reaction assisted rDNA fingerprinting of developed mycorrhizas. Six distinct morphotypes of mycorrhiza developed on non-mycorrhizal seedlings grown in forest humus. Three of the morphotypes (white1-, black-, and brown-type) were, respectively, associated with the fungi Suillus bovinus (L. ex Fr.) O. Kuntze, Cenococcum geophilum Fr., and Thelephora terrestris Ehrh.:Fr. (= Tomentella radiosa (P. Karst.) Rick). A fourth pink-type morphotype displayed features indicating root colonization by Tomentellopsis submollis (Svrcek) Hjortstam, but this could not be confirmed because of a lack of source restriction fragment length polymorphism (RFLP) data. Brown-type mycorrhiza were the first to appear after seedling transplantation and black-type mycorrhizas showed local and dispersed root colonization dynamics. Mycorrhiza development in the unfertilized nursery peat substrate was restricted to a single unidentifiable brown-type morphotype, which appeared after 44 days. Rapid colonization of adjacent non-mycorrhizal seedlings by Tomentellopsis submollis, but not S. bovinus, was detected following the introduction of preinoculated seedlings into the humus or peat microcosms. The biomass of seedlings grown in nursery peat, regardless of mycorrhizal status, was significantly lower than that of mycorrhizal seedlings grown in humus. These findings support and extend previous bait seedling studies, as they provide a primary in situ characterization of distinct root colonization strategies of mycorrhizal species in forest humus and nursery peat.
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Farias-Larios, J., S. Guzman-Gonzalez, and A. Michel-Rosales. "The Advances in the Study on Mycorrhizas of Fruit Trees in Dry Tropics of Mexico." HortScience 31, no. 4 (August 1996): 684c—684. http://dx.doi.org/10.21273/hortsci.31.4.684c.
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The productivity of marginal soils frequently found in the arid tropics might be improved by using VAM fungi as “biofertilizer” and as a tool of sustainable agricultural systems. Study of mycorrhizas of fruit trees was performed in 1987 in western Mexico. More progress has been made in resources, taxonomy, anatomy and morphology, physiology, ecology, effects, and application of mycorrhizas in fruit trees and ornamental plants production. Currently, five genera has been identified and inoculated plants showed significant difference in respect to plants not inoculated with mycorrhizal fungi. Citrus trees were highly dependent on mycorrhizae for normal growth and development, while the banana plants showed lower levels of root colonization by different strains of VAM fungi. The added endomycorrhizal inoculum significantly increased root fungal colonization in fruit trees and reduce the time in nursery. The current status and research trends in the study of fruit tree mycorrhizas in western Mexico are introduced, and the application prospects in sustainable agriculture also are discussed.
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Doré, Jeanne, Roland Marmeisse, Jean-Philippe Combier, and Gilles Gay. "A Fungal Conserved Gene from the Basidiomycete Hebeloma cylindrosporum Is Essential for Efficient Ectomycorrhiza Formation." Molecular Plant-Microbe Interactions® 27, no. 10 (October 2014): 1059–69. http://dx.doi.org/10.1094/mpmi-03-14-0087-r.
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We used Agrobacterium-mediated insertional mutagenesis to identify genes in the ectomycorrhizal fungus Hebeloma cylindrosporum that are essential for efficient mycorrhiza formation. One of the mutants presented a dramatically reduced ability to form ectomycorrhizas when grown in the presence of Pinus pinaster. It failed to form mycorrhizas in the presence of glucose at 0.5 g liter–1, a condition favorable for mycorrhiza formation by the wild-type strain. However, it formed few mycorrhizas when glucose was replaced by fructose or when glucose concentration was increased to 1 g liter–1. Scanning electron microscopy examination of these mycorrhizas revealed that this mutant was unable to differentiate true fungal sheath and Hartig net. Molecular analyses showed that the single-copy disrupting T-DNA was integrated 6,884 bp downstream from the start codon, of an open reading frame potentially encoding a 3,096-amino-acid-long protein. This gene, which we named HcMycE1, has orthologs in numerous fungi as well as different other eukaryotic microorganisms. RNAi inactivation of HcMycE1 in the wild-type strain also led to a mycorrhizal defect, demonstrating that the nonmycorrhizal phenotype of the mutant was due to mutagenic T-DNA integration in HcMycE1. In the wild-type strain colonizing P. pinaster roots, HcMycE1 was transiently upregulated before symbiotic structure differentiation. Together with the inability of the mutant to differentiate these structures, this suggests that HcMycE1 plays a crucial role upstream of the fungal sheath and Hartig net differentiation. This study provides the first characterization of a fungal mutant altered in mycorrhizal ability.
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Walker, Christopher. "Sitka spruce mycorrhizas." Proceedings of the Royal Society of Edinburgh. Section B. Biological Sciences 93, no. 1-2 (1987): 117–29. http://dx.doi.org/10.1017/s0269727000006333.
Full textAbstract:
SynopsisRelatively little research has been done on mycorrhizas of Sitka spruce, although greenhouse studies have confirmed that its growth can be improved by the introduction of mycorrhizal fungi. Work in nurseries is difficult under British conditions and it probably will be necessary to disinfest soil in seedbeds before mycorrhizal treatment can be applied. Results from forest trials show that inoculation with selected mycorrhizal fungi can give significant early growth effects, though how long these will persist is unknown. In such work, careful attention must be given to selection of controls. Features covered in this review include a discussion of fungi mycorrhizal with Sitka spruce, identification of mycorrhizas, nutrient uptake, and growth enhancement of seedlings and transplants.
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Korhonen, Anna, Tarja Lehto, Jaakko Heinonen, and Tapani Repo. "Whole-plant frost hardiness of mycorrhizal (Hebeloma sp. or Suillus luteus) and non-mycorrhizal Scots pine seedlings." Tree Physiology 39, no. 6 (October 29, 2018): 951–60. http://dx.doi.org/10.1093/treephys/tpy105.
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Abstract Ectomycorrhizal trees are common in the cold regions of the world, yet the role of the mycorrhizal symbiosis in plant cold tolerance is poorly known. Moreover, the standard methods for testing plant frost hardiness may not be adequate for roots and mycorrhizas. The aims of this study were to compare the frost hardiness of mycorrhizal and non-mycorrhizal Scots pine (Pinus sylvestris L.) seedlings and to test the use of reverse-flow root hydraulic conductance (Kr) measurement for root frost hardiness determination. Mycorrhizal (Hebeloma sp. or Suillus luteus) and non-mycorrhizal seedlings were grown in controlled-environment chambers for 13 weeks. After this, half of the plants were allotted to a non-hardening treatment (long day and high temperature, same as during the preceding growing season) and the other half to a hardening (short day and low temperature) ‘autumn’ treatment for 4 weeks. The intact seedlings were exposed to whole-plant freezing tests and the needle frost hardiness was measured by relative electrolyte leakage (REL) method. The seedlings were grown for three more weeks for visual damage assessment and Kr measurements using a high-pressure flow meter (HPFM). Mycorrhizas did not affect the frost hardiness of seedlings in either hardening treatment. The effect of the hardening treatment on frost hardiness was shown by REL and visual assessment of the aboveground parts as well as Kr of roots. Non-mycorrhizal plants were larger than mycorrhizal ones while nitrogen and phosphorus contents (per unit dry mass) were similar in all mycorrhiza treatments. In plants with no frost exposure, the non-mycorrhizal treatment had higher Kr. There was no mycorrhizal effect on plant frost hardiness when nutritional effects were excluded. Further studies are needed on the role of mycorrhizas especially in the recovery of growth and nutrient uptake in cold soils in the spring. The HPFM is useful novel method for assessment of root damage.
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MOYERSOEN, BERNARD, IAN J. ALEXANDER, and ALASTAIR H. FITTER. "Phosphorus nutrition of ectomycorrhizal and arbuscular mycorrhizal tree seedlings from a lowland tropical rain forest in Korup National Park, Cameroon." Journal of Tropical Ecology 14, no. 1 (January 1998): 47–61. http://dx.doi.org/10.1017/s0266467498000054.
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The relationship between mycorrhizal colonisation and phosphorus acquired by seedlings of the arbuscular mycorrhizal tree Oubanguia alata Bak f. (Scytopetalaceae) and the ectomycorrhizal tree Tetraberlinia moreliana Aubr. (Caesalpiniodeae) was evaluated at low and high inorganic phosphorus availability. AM colonisation was positively correlated with phosphorus uptake by O. alata at low, but not at high phosphorus availability. Seedlings growth was positively related to arbuscular mycorrhizal colonisation at both low and high phosphorus availability, suggesting that growth promotion by arbuscular mycorrhizas is not simply related to an increase of phosphorus uptake. In contrast, phosphorus uptake by T. moreliana was correlated with EM colonisation at both low and high phosphorus availability, but there was no relationship between growth and ectomycorrhizal colonisation. Promotion of phosphorus uptake by arbuscular mycorrhizas and ectomycorrhizas at low phosphorus availability is consistent with the co-occurrence of the two types of mycorrhiza in tropical rain forests where available soil phosphorus is low. However, ectomycorrhizal colonisation may also be of advantage where inputs of phosphorus rich litter raise the phosphorus status of the soil, as seen in the groves of ectomycorrhizal trees in Korup National Park, and may be one of the factors reinforcing local dominance by these trees.
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Wurzburger, Nina, and Caroline S. Bledsoe. "Comparison of ericoid and ectomycorrhizal colonization and ectomycorrhizal morphotypes in mixed conifer and pygmy forests on the northern California coast." Canadian Journal of Botany 79, no. 10 (October 1, 2001): 1202–10. http://dx.doi.org/10.1139/b01-078.
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On the northern California coast, mixed conifer forests occur on younger, relatively fertile terraces, whereas mesic and hydric pygmy forests occur on older, infertile, poorly drained terraces. We characterized mycorrhizal associations, ectomycorrhizal morphotypes, and colonization levels for nine plant species from three plant communities (mixed conifer, mesic pygmy, and hydric pygmy). Pinus contorta ssp. bolanderi (Parl.) Critchf. and Pinus muricata D. Don were ectomycorrhizal; all ericaceous plants formed ericoid mycorrhizas except Arctostaphylos nummularia A. Gray, which formed only arbutoid mycorrhizas. Arbuscular mycorrhizas were not observed, even on Cupressus goveniana ssp. pigmaea (Lemmon) J. Bartel. Ectomycorrhizal colonization was significantly lower in pygmy forests, while ericoid mycorrhizal colonization was significantly higher, as compared with the mixed conifer forest. Ectomycorrhizal and ericoid mycorrhizal colonization was greater on hummocks than in swales at hydric pygmy sites. Thirteen distinct ectomycorrhizal and arbutoid mycorrhizal morphotypes were observed: eight only on Pinus spp. and two only on A. nummularia. Two morphotypes were found only in mixed conifer, and eight were found only in pygmy communities. Distribution of morphotypes may reveal habitat and (or) host adaptation by ectomycorrhizal fungi.Key words: ectomycorrhizal morphotypes, ericoid mycorrhizas, pygmy forest, Ericaceae, mycorrhizal colonization, low-fertility soils.
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Unrug, Juliusz, and Katarzyna Turnau. "Mycorrhiza of Dryopteris carthusiana in southern Poland." Acta Mycologica 34, no. 2 (August 20, 2014): 305–14. http://dx.doi.org/10.5586/am.1999.020.
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The research on mycorrhiza of <i>Dryopteris carthusiana</i> from natural sites and those contaminated by heavy metals (Niepołomice Forest), both on lowlands and mountainous areas in Poland, was carried out. Mycorrhizal colonization of <i>Arum</i>-type was higher in ferns growing on tree stumps than in specimens developing directly on the soil. Additionally, an increase in mycorrhiza intensity and arbuscular richness with the rising ground humidity was observed. In comparison to natural sites, mycorrhizas from the areas contaminated by heavy metals were much less developed and the roots were often infected by parasites. Two morphotypes of mycorrhizal fungi have been described The most common was a fine endophyte (<i>Glomales</i>).
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Logan, VS, PJ Clarke, and WG Allaway. "Mycorrhizas and Root Attributes of Plants of Coastal Sand-Dunes of New South Wales." Functional Plant Biology 16, no. 1 (1989): 141. http://dx.doi.org/10.1071/pp9890141.
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Root samples of 41 sand-dune plant species in 28 families were collected from sites along the coast of New South Wales during spring 1987. Of the species, 36 had vesicular-arbuscular mycorrhizas, with vesicles and internal and external hyphae. Among these species there was great variation in the pro- portion of root length colonised by vesicular-arbuscular mycorrhizal fungi (from 1 to 96%); in 33 species over 10% of root length was infected. Of the vesicular-arbuscular mycorrhizal species, 21 showed arbuscules, and 16 had intracellular hyphal coils. In four plant species mycorrhizas were not found in the single samples examined; ericoid mycorrhizas were present in the remaining species, Leucopogon parviflorus, but its vesicular-arbuscular mycorrhizal status could not be assessed. The results, though preliminary, may reflect a high vesicular-arbuscular mycorrhizal status of vegetation of coastal sand-dunes of New South Wales. This would be likely to enhance plant nutrition and sandbinding, and to have implications for sand-dune management.
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Ramakrishnan, K., and G. Bhuvaneswari. "Influence on Different Types of Mycorrhizal Fungi on Crop Productivity in Ecosystem." International Letters of Natural Sciences 38 (May 2015): 9–15. http://dx.doi.org/10.18052/www.scipress.com/ilns.38.9.
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Mycorrhizal fungi greatly enhanced the ability of plants to take up phosphorus and other nutrients those are relatively immobile and exist in low concentration in the soil solution. Fungi can be important in the uptake of other nutrients by the host plant. Mycorrhizae establish symbiotic relationships with plants and play an essential role in plant growth, disease protection, and overall soil quality. Of the seven types of mycorrhizae described in current scientific literature (arbuscular, ecto, ectendo, arbutoid, monotropoid, ericoid and orchidaceous mycorrhizae), the arbuscular and ectomycorrhizae are the most abundant and widespread. This chapter presents an overview of current knowledge of mycorrhizal interactions, processes, and potential benefits to society. The molecular basis of nutrient exchange between arbuscular mycorrhizal (AM) fungi and host plants is presented; the role of AM fungi in disease protection, alleviation of heavy metal stress and increasing grain production. Most land plants form associations with mycorrhizal fungi. Mycorrhizas are mutualistic associations between fungi and plant roots. They are described as symbiotic because the fungus receives photo synthetically derived carbon compounds and the plant has increased access to mineral nutrients and sometimes water.
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Ramakrishnan, K., and G. Bhuvaneswari. "Influence on Different Types of Mycorrhizal Fungi on Crop Productivity in Ecosystem." International Letters of Natural Sciences 38 (May 6, 2015): 9–15. http://dx.doi.org/10.56431/p-9pjdc8.
Full textAbstract:
Mycorrhizal fungi greatly enhanced the ability of plants to take up phosphorus and other nutrients those are relatively immobile and exist in low concentration in the soil solution. Fungi can be important in the uptake of other nutrients by the host plant. Mycorrhizae establish symbiotic relationships with plants and play an essential role in plant growth, disease protection, and overall soil quality. Of the seven types of mycorrhizae described in current scientific literature (arbuscular, ecto, ectendo, arbutoid, monotropoid, ericoid and orchidaceous mycorrhizae), the arbuscular and ectomycorrhizae are the most abundant and widespread. This chapter presents an overview of current knowledge of mycorrhizal interactions, processes, and potential benefits to society. The molecular basis of nutrient exchange between arbuscular mycorrhizal (AM) fungi and host plants is presented; the role of AM fungi in disease protection, alleviation of heavy metal stress and increasing grain production. Most land plants form associations with mycorrhizal fungi. Mycorrhizas are mutualistic associations between fungi and plant roots. They are described as symbiotic because the fungus receives photo synthetically derived carbon compounds and the plant has increased access to mineral nutrients and sometimes water.
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Dexheimer, Jean, Joëlle Gerard, Jean-Pierre Leduc, and Gérard Chevalier. "Étude ultrastructurale comparée des associations symbiotiques mycorhiziennes Helianthemum salicifolium – Terfezia claveryi et Helianthemum salicifolium – Terfezia leptoderma." Canadian Journal of Botany 63, no. 3 (March 1, 1985): 582–91. http://dx.doi.org/10.1139/b85-073.
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The authors have studied the ultrastructural organization of two synthetic mycorrhizas between Helianthemum salicifolium (L.) Mill. (Cistaceae) and Terfezia claveryi Chat. or Terfezia leptoderma Tul. (Ascomycetes, Terfeziaceae). With Terfezia claveryi an endomycorrhiza is formed with many of the hyphae hugging the inside surface of the cell wall. The cytoplasmic volume of the mycorrhizal cells is not significantly increased. With Terfezia leptoderma an ectomycorrhiza without a sheath is formed, but there is a typical Hartig net. These two types of mycorrhiza constitute examples of biotrophism.
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Milović, Marina, Marko Kebert, and Saša Orlović. "How mycorrhizas can help forests to cope with ongoing climate change?" Šumarski list 145, no. 5-6 (June 24, 2021): 279–86. http://dx.doi.org/10.31298/sl.145.5-6.7.
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The ongoing climate change have multi-faceted effects not only on metabolism of plants, but also on the soil properties and mycorrhizal fungal community. Under climate change the stability of the entire forest ecosystems and the carbon balance depend to a large degree on the interactions between trees and mycorrhizal fungi. The main drivers of climate change are CO<sub>2</sub> enrichment, temperature rise, altered precipitation patterns, increased N deposition, soil acidification and pollutants, ecosystem fragmentation and habitat loss, and biotic invasion. These drivers can impact mycorrhizal community directly and indirectly. We discussed the influence of each driver on mycorrhizal community and outlined how mycorrhizas play an important role in the resilience and recovery of forest ecosystems under climate change, by mitigating detrimental effects of CO<sub>2</sub> enrichment, temperature rise, drought, lack of nutrients, soil acidification, pollutants, pests, and diseases. Conservation of the overall biodiversity in forest ecosystems as well as providing the most favourable conditions for the development of mycorrhizae can contribute to increasing the resilience of forest ecosystems to climate change.
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Gianinazzi-Pearson, Vivienne, Armelle Gollotte, Benoit Tisserant, Philipp Franken, Eliane Dumas-Gaudot, Marie-Claude Lemoine, Diederik van Tuinen, Silvio Gianinazzi, and Jeanine Lherminier. "Cellular and molecular approaches in the characterization of symbiotic events in functional arbuscular mycorrhizal associations." Canadian Journal of Botany 73, S1 (December 31, 1995): 526–32. http://dx.doi.org/10.1139/b95-292.
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Arbuscular mycorrhizas represent the most widespread, and probably most ancient, type of plant–fungus association in which the large majority of terrestrial plants must have evolved with compatibility systems towards the fungal symbionts. Cellular interactions leading to reciprocal morphofunctional integration between symbionts during mycorrhiza establishment are complex. Some plant genes and cellular events may be shared with nodulation processes, but there is evidence of molecular modifications specific to arbuscular mycorrhiza formation. Plant defence responses, which are normally weakly activated during the symbiotic state, are strongly elicited by arbuscular mycorrhizal fungi in genetically altered, resistant hosts suggesting control over defence gene expression during establishment of a successful symbiosis. Modifications are also induced in the fungal symbionts during colonization of host tissues, with changes in wall metabolism and protein expression. Nothing is known of the genetic make-up of arbuscular mycorrhizal fungi which are recalcitrant to pure culture. Recent cloning of DNA from these fungi opens the possibility of identifying functional genes in order to study their regulation and role in symbiosis establishment. Key words: arbuscular mycorrhiza, reciprocal symbiosis, molecular mechanisms, plant determinants, fungal molecules.
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Abbott, Lynette. "Soil health: A role for arbuscular mycorrhizas." Open Access Government 42, no. 1 (April 12, 2024): 16–417. http://dx.doi.org/10.56367/oag-042-11220.
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Soil health: A role for arbuscular mycorrhizas Lynette Abbott from The University of Western Australia, focuses on soil health again, this time examining the role of arbuscular mycorrhizas. Mycorrhizas are common associations between plants and highly specialised fungi that participate in important soil health processes, including nutrient uptake by plants. This can include nutrients from fertilisers, the breakdown of soil organic matter, and soil minerals. Arbuscular mycorrhizal (AM) fungi form extensive networks of hyphae in soil that extend around roots and increase the soil volume that can be explored. In addition to nutrient scavenging, the hyphae contribute to maintaining a friable soil structure that benefits root growth and even helps plants access water in tiny soil pores when soil conditions are dry. Mycorrhizas may also contribute to protection against root disease.
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Cavagnaro, Timothy R., Shannon K. Sokolow, and Louise E. Jackson. "Mycorrhizal effects on growth and nutrition of tomato under elevated atmospheric carbon dioxide." Functional Plant Biology 34, no. 8 (2007): 730. http://dx.doi.org/10.1071/fp06340.
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Arbuscular mycorrhizas are predicted to be important in defining plant responses to elevated atmospheric CO2 concentrations. A mycorrhiza-defective tomato (Solanum lycopersicum L.) mutant with reduced mycorrhizal colonisation (rmc) and its mycorrhizal wild-type progenitor (76R MYC+) were grown under ambient and elevated atmospheric CO2 concentrations (eCO2) in a controlled environment chamber-based pot study. Plant growth, nutrient contents and mycorrhizal colonisation were measured four times over a 72-day period. The 76R MYC+ plants generally had higher concentrations of P, N and Zn than their rmc counterparts. Consistent with earlier studies, mycorrhizal colonisation was not affected by eCO2. Growth of the two genotypes was very similar under ambient CO2 conditions. Under eCO2 the mycorrhizal plants initially had higher biomass, but after 72 days, biomass was lower than for rmc plants, suggesting that in this pot study the costs of maintaining carbon inputs to the fungal symbiont outweighed the benefits with time.
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KASURINEN, A., T. HOLOPAINEN, and S. ANTTONEN. "Mycorrhizal colonisation of highbush blueberry and its native relatives in central Finland." Agricultural and Food Science 10, no. 2 (January 2, 2001): 113–19. http://dx.doi.org/10.23986/afsci.5683.
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Transmission electromicroscopy, trypan blue staining in combination with stereomicroscope analysis and biochemical ergosterol assay were used to study the mycorrhizal symbionts in wild bilberry (Vaccinium myrtillus), bog whortleberry (Vaccinium uliginosum) and highbush blueberry (Vaccinium corymbosum) roots. TEM-analysis showed that in all species ericoid mycorrhizas formed hyphae coil inside the epidermal root cells. In stereomicroscopic viewing the highest mycorrhizal colonisation was observed in the roots of wild bilberries (51%), whereas according to the ergosterol assay the highest total fungal biomass of roots was found in bog whortleberries (209 mg g-1 of root d. wt). Both ergosterol and microscopical method showed that the mycorrhizal associations in blueberry cultivars and their wild relatives growing on natural soil medium are frequent, although ericoid mycorrhiza formation of highbush blueberries was somewhat weaker than that of wild bilberries and bog whortleberries.
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Turnau, Katarzyna, Ewa Gucwa, Piotr Mleczko, and Barbara Godzik. "Metal content in fruit-bodies and mycorrhizas of Pisolithus arrhizus from zinc wastes in Poland." Acta Mycologica 33, no. 1 (August 20, 2014): 59–67. http://dx.doi.org/10.5586/am.1998.005.
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<i>Pisolithus arrhizus</i> has been selected for investigation as one of the ectomycorrhizal species most resistant to stress factors. Metal content in fruit-bodies and mycorrhizas was estimated to evaluate their role as bioindicators and to check whether mycorrhizas have any special properties for heavy metal accumulation. Fruit-bodies and mycorrhizas were collected from zinc wastes in Katowice-Wełnowiec and analyzed using conventional atomic absorption spectroscopy and energy dispersive spectroscopy accompanying scanning electron microscopy. Differences in tendencies to accumulate metals within sporophores and mycorrhizas were found. The fruit-bodies accumulated Al (up to 640 µg g<sup>-1</sup>), while high concentrations of Al, Zn, Fe, Ca and Si were noted in the outer mantle of the mycorrhizas. in the material secreted and in the mycelium wali. The content of elements varied depending on the agę of mycorrhizas. The ability of extramatrical mycelium and hyphae forming mycorrhizal mantle to immobilize potentially toxic elements might indicate biofiltering properties though thc next step should include investigations on ability of the fungus to prevent element uptake by the plant.
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Egger, Keith N., and David S. Hibbett. "The evolutionary implications of exploitation in mycorrhizas." Canadian Journal of Botany 82, no. 8 (August 1, 2004): 1110–21. http://dx.doi.org/10.1139/b04-056.
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Some views of mutualism, where the fitness of two symbiotic partners is higher in association than when apart, assume that they necessarily evolve towards greater benefit for the partners. Most mutualisms, however, seem prone to conflicts of interest that destabilize the partnership. These conflicts arise in part because mutualistic outcomes are conditional, depending upon complex interactions between environmental, developmental, and genotypic factors. Mutualisms are also subject to exploitation or cheating. Although various compensating mechanisms have been proposed to explain how mutualism can be maintained in the presence of exploiters, none of these mechanisms can eliminate exploitation. In this paper we explore various compensating mechanisms in mycorrhizas, examine the evidence for exploitation in mycorrhizas, and conclude that mycorrhizal mutualisms exhibit characteristics that are more consistent with a concept of reciprocal parasitism. We propose that researchers should not assume mycorrhizas are mutualistic based upon structural characteristics or limited functional studies showing bilateral exchange and should view mycorrhizas as occupying a wider range on the symbiotic continuum, including commensalism and antagonism. We recommend that comparative studies of mycorrhizas incorporate other types of root associations that have traditionally been considered antagonistic.Key words: mycorrhizas, mutualism, exploiters, compensating mechanisms, symbiotic continuum.
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Rieger, Andreas, Martin Guttenberger, and Rüdiger Hampp. "Soluble Carbohydrates in Mycorrhized and Non-Mycorrhized Fine Roots of Spruce Seedlings." Zeitschrift für Naturforschung C 47, no. 3-4 (April 1, 1992): 201–4. http://dx.doi.org/10.1515/znc-1992-3-406.
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Abstract We present results on the compartmentation of carbohydrates such as sucrose, glucose, fructose, and mannose in different parts of an ectomycorrhiza established between Picea abies and Amanita muscaria and compare it with non-mycorrhized fine roots. Lyophilized mycorrhizas and fine roots (< 2 mm length) were dissected into about 0.5 mm thick slices which represent 4 zones of different physiological functions. The total amount of the analyzed carbohydrates was about 30% higher in non-mycorrhized (n-myc) compared to mycorrhized (myc) fine roots, with sucrose being the dominating sugar in both root types. A longitudinal distinction of sucrose pools showed lowest levels in the middle parts of a mycorrhiza, which represent areas of most intense symbiotic interaction. Fine roots without fungal infection did not show longitudinal variations in sugar content.
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Massicotte, Hugues B., R. Larry Peterson, Lewis H. Melville, and Linda E. Tackaberry. "Hudsonia ericoides and Hudsonia tomentosa: Anatomy of mycorrhizas of two members in the Cistaceae from Eastern Canada." Botany 88, no. 6 (June 2010): 607–16. http://dx.doi.org/10.1139/b10-035.
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Most species in the family Cistaceae are found in the Mediterranean basin. Several hosts are of special interest, owing to their associations with truffle species, while many are important as pioneer plants in disturbed areas and in soil stabilization. For these reasons, understanding their root systems and their associated fungal symbionts is important. Most studies of the structure of mycorrhizas in this family involve two genera, Cistus and Helianthemum . The present study examines structural features of mycorrhizas in two North American species, Hudsonia ericoides L. and Hudsonia tomentosa Nutt. Root systems of both species are highly branched with most fine roots colonized by mycorrhizal fungi. Based on morphological features, several mycorrhizal fungi were identified; structural details also provided evidence of more than one fungal symbiont for each host species. All mycorrhizas had a multi-layered fungal mantle and Hartig net hyphae confined to radially elongated epidermal cells; no intracellular hyphae were observed. Although the Hartig net was confined to the epidermis, the outer row of cortical cell walls lacked suberin, a known barrier to fungal penetration. Mycorrhizas in H. ericoides and H. tomentosa differed from those of Cistus and Helianthemum species that have a Hartig net that extends into the root cortex, as well as frequently present intracellular hyphae.
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Mcgee, P. "Mycorrhizal Associations of Plant-Species in a Semiarid Community." Australian Journal of Botany 34, no. 5 (1986): 585. http://dx.doi.org/10.1071/bt9860585.
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Of 93 species in 37 families occurring in a semiarid open mallee community near Murray Bridge, South Australia, 85 species were mycorrhizal. Vesicular-arbuscular mycorrhizas (VAM) were more common than other types of mycorrhizas observed. Genera not previously known to form ectomycorrhizas include Astroloma (Epacridaceae), Comesperma (Polygalaceae), Thysanotus (Asphodelaceae: Liliflorae), Baeckea and Calytrix (Myrtaceae), Dampiera (Goodeniaceae), Podotheca and Toxanthes (Inulae: Asteraceae). Many species were found with both ectomycorrhizas and VAM, with annuals having both VAM and ectomycorrhizas for the whole growing season and perennials usually exhibiting either a predominantly VAM or ectomycorrhizal association. Vesicles were present in plant species not commonly thought of as mycorrhizal hosts.
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Scheltema, MA, LK Abbott, and AD Robson. "Seasonal variation in the infectivity of VA mycorrhizal fungi in annual pastures in a Mediterranean environment." Australian Journal of Agricultural Research 38, no. 4 (1987): 707. http://dx.doi.org/10.1071/ar9870707.
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The seasonal variation in the rate and extent of formation of mycorrhizas in pasture soils from two sites in south-west Australia was examined. Undisturbed soil cores were taken on eight occasions throughout the year, sown with Trifolium subterraneum L. and maintained in a glasshouse. At each collection time the extent of formation of mycorrhizas was measured 3 and 6 weeks after sowing.There was no seasonal variation in the extent of mycorrhizas formed in undisturbed soil cores at one site, hut at the other site the extent of mycorrhizas decreased over time. The rate of formation of mycorrhizas was most rapid when cores were collected immediately after the opening rains of the season.Similar species of fungi were present at both sites; however, the rate and extent of infection formed by each species differed between the sites. At both sites the infectivity of A. laevis and fine endophyte decreased throughout the winter months, but the infectivity of Glomus spp. did not change. Neither the total spore number nor an estimate of the number of infective propagules reflected the infectivity of the total population of VA mycorrhizal fungi measured simultaneously at the two sites.
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Dickie, Ian A., Nina Koele, Joel D. Blum, James D. Gleason, and Matthew S. McGlone. "Mycorrhizas in changing ecosystems,." Botany 92, no. 2 (February 2014): 149–60. http://dx.doi.org/10.1139/cjb-2013-0091.
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Ecosystems change between arbuscular mycorrhizal and ectomycorrhizal vegetation dominance over anthropological and geological time scales, yet consequences for ecosystem function are unclear. We review four hypotheses for the effect of mycorrhizal status on ecosystem function. Specifically, that differences between ectomycorrhizal and arbuscular mycorrhizal dominated ecosystems are driven by (1) foliar trait differences, (2) positive plant–soil feedback in ectomycorrhizal plants, (3) differences in the ability to dissolve rocks as a source of nutrition, and (4) differences in the ability to use organic nutrients. We find no universal difference in foliar traits with mycorrhizal status. A spatial simulation suggests that positive plant–soil feedback in ectomycorrhizal plants is unlikely to drive ecosystem differences. However, negative feedback appears to be more common in arbuscular mycorrhizal trees than ectomycorrhizal trees and may represent an important ecosystem difference. Rock dissolution occurs under both mycorrhizal types but may differ in rate. Hypothesis 4 was the best supported: a model and some field evidence suggest that decoupling of carbon and nutrients in ectomycorrhizal decomposition leads to inhibition of saprotrophic mineralization, with context-dependent effects. Greater understanding of organic nutrient utilization differences may be key to improving incorporation of mycorrhizas in ecosystem ecology.
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Sarsekova, Dani, Sezgin Ayan, and Abzhanov Talgat. "Ectomycorrhizal Flora Formed by Main Forest Trees in the Irtysh River Region of Central and Northeastern Kazakhstan." South-east European forestry 11, no. 1 (May 11, 2020): 61–69. http://dx.doi.org/10.15177/seefor.20-06.
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In this study, the aim was to determine and identify symbiotically living ectomycorrhizas of the main tree species forming forests in central and northeastern Kazakhstan. Surveys were conducted on the right bank of the Irtysh River in a mixed forest of Pinus sylvestris, Picea obovata and Betula pendula trees. The collection was formed and the primary identification of voucher samples of fruiting bodies of macromycetes collected as ectomycorrhiza forming fungi was completed. In the collection and species identification of fruiting bodies, standard methods were used. A total of 30 ectomycorrhizas belonging to Agaricomycetes were identified. The distribution of 30 species into families is as follows: Suillaceae (8), Russulaceae (7), Cortinariaceae (4), Boletaceae (3), Tricholomataceae (2), Amanitaceae (1), Cantharellaceae (1), Gomphaceae (1), Gomphidiaceae (1), Paxillaceae (1), and Bankeraceae (1). The richest genus on account of the number of species was Suillus (8). Concerning the woody host species, 17 mycorrhizas were determined to build symbiosis with P. sylvestris, 8 mycorrhizas with B. pendula, 6 mycorrhizas with Populus tremula, 1 mycorrhiza with P. obovata, 1 mycorrhiza with Quercus robur, 1 mycorrhiza with Salix sp., and 1 mycorrhiza with Pinus densiflora Siebold and Zuccarini. Ectomycorrhizas should be used as a major performance-enhancing tool in afforestation and restoration studies in the Irtysh River basin under extreme ecological conditions and under climate change effects.
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Last, F. T., P. A. Mason, J. Wilson, K. Ingleby, R. C. Munro, L. V. Fleming, and J. W. Deacon. "‘Epidemiology’ of sheathing (ecto-) mycorrhizas in unsterile soils: a case study of Betula pendula." Proceedings of the Royal Society of Edinburgh. Section B. Biological Sciences 85, no. 3-4 (1985): 299–315. http://dx.doi.org/10.1017/s0269727000004085.
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SynopsisSequential observations were made of the effects on root development of inoculating Betula pendula seedlings during propagation with sheathing mycorrhizal fungi, Amanita muscaria, Hebeloma sacchariolens or Paxillus involutus. After propagation, the seedlings were grown for two seasons in four different soils (two mineral soils and two peats) which were not sterilised.While all inoculated seedlings had similar numbers of mycorrhizas at planting, numbers subsequently increased most rapidly with P. involutus and least rapidly with A. muscaria. From the end of the first season onwards, the uninoculated controls had as many mycorrhizas as seedlings inoculated with either A. muscaria or H. sacchariolens. These numbers were, however, usually exceeded on plants inoculated with P. involutus.The mycorrhizas developing on the controls, and on seedlings inoculated with A. muscaria, were attributable after planting into the unsterile soils, to naturally occurring soil-borne inocula of species of Cenococcum, Hebeloma, Inocybe, Laccaria, Paxillus and Thelephora etc. Those developing on seedlings inoculated with P. involutus were all attributable to this inoculant fungus in the first year but, in the second year, the proportions decreased to 19—14%. With H. sacchariolens, at least 90% of the mycorrhizas in the two mineral soils and one of the peats (a sedge peat) were attributable in years 1 and 2 to the inoculant fungus. In the other peat (Sphagnum peat), the proportion of mycorrhizas attributable to H. sacchariolens decreased to 25% by the end of the first year and totally disappeared in the second.The continued ability of H. sacchariolensto form mycorrhizas in a range of unsterile soils, to the virtual exclusion of mycorrhizas attributable to other fungi, is thought to be characteristic of fungi that occur early in mycorrhizal successions. In contrast,A. muscaria(a late-stage fungus), was unable to form mycorrhizas after inoculated seedlings were transferred from controlled axenic conditions to unsterilised field soils.Two arbiters of root growth were measured—numbers of roots and their dry weights. Whereas inoculations with H. sacchariolens significantly decreased numbers in the latter part of the first season, they either had no effects on dry weights as in the mineral soils or significantly increased them as in the peats. In the second season, there was further evidence, sometimes contradictory, showing that inoculations can appreciably alter the structure of developing root systems.
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Braunberger, P. G., L. K. Abbott, and A. D. Robson. "Early vesicular-arbuscular mycorrhizal colonisation in soil collected from an annual clover-based pasture in a Mediterranean environment: soil temperature and the timing of autumn rains." Australian Journal of Agricultural Research 48, no. 1 (1997): 103. http://dx.doi.org/10.1071/a96049.
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The results of 2 experiments investigating the early stages of the formation of vesicular- arbuscular (VA) mycorrhizas in response to both soil temperature and the timing of autumn rains are reported for a Mediterranean environment in the south-west of Western Australia. In Expt 1, treatments including an early break, a late break, and a false break followed by a late break were applied to a mixed and sieved field soil collected dry in the summer and placed in pots in a glasshouse. In each break, pots were watered to field capacity and planted with subterranean clover (Trifolium subterraneum) or capeweed (Arctotheca calendula). In early and false breaks, both initiated on the same day in early autumn, the soil temperature was maintained at 30°C, and in the late break, initiated 50 days later in autumn, the soil temperature was maintained at 18°C. In both early and late breaks, pots were watered to field capacity for either 21 or 42 days when plant and mycorrhizal variables were assessed. In a false break, pots were watered to field capacity for 7 days after which the soil was allowed to dry and newly emerged plants died. These pots were then rewatered and replanted at the same time as pots receiving a late break, and subjected to the same soil temperature (18°C). In Expt 2 performed the following year, soil temperature was maintained at 31 or 18°C in both early and late breaks. Pots were planted with clover and watered to field capacity for 21 or 42 days, when plant and mycorrhizal variables were assessed. In Expt 1, VA mycorrhizal colonisation of both clover and capeweed was initially low in an early break compared with levels observed in a late break. Only mycorrhizas formed by Glomus spp. were observed in the early break, whereas mycorrhizas of Glomus, Acaulospora, and Scutellospora spp. and fine endophytes were observed in the late break. Colonisation was decreased by a false break, predominantly because of a decrease in formation of mycorrhizas of Glomus spp. In Expt 2, mycorrhizas of Glomus spp. predominated in warm soil in both early and late breaks and mycorrhizas of Acaulospora spp., Scutellospora spp., and fine endophytes were observed in greater abundance in cool soil in early and late breaks. These experiments indicate that soil temperature at the time of the break will have a large impact on both the overall levels of VA mycorrhizal colonisation of pasture plants and colonisation by different fungi. In addition, fungi that remain quiescent in warm soil may avoid damage in a false break.
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Maldonado-Mendoza, Ignacio E., Gary R. Dewbre, and Maria J. Harrison. "A Phosphate Transporter Gene from the Extra-Radical Mycelium of an Arbuscular Mycorrhizal Fungus Glomus intraradices Is Regulated in Response to Phosphate in the Environment." Molecular Plant-Microbe Interactions® 14, no. 10 (October 2001): 1140–48. http://dx.doi.org/10.1094/mpmi.2001.14.10.1140.
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The majority of vascular flowering plants are able to form symbiotic associations with arbuscular mycorrhizal fungi. These symbioses, termed arbuscular mycorrhizas, are mutually beneficial, and the fungus delivers phosphate to the plant while receiving carbon. In these symbioses, phosphate uptake by the arbuscular mycorrhizal fungus is the first step in the process of phosphate transport to the plant. Previously, we cloned a phosphate transporter gene involved in this process. Here, we analyze the expression and regulation of a phosphate transporter gene (GiPT) in the extra-radical mycelium of the arbuscular mycorrhizal fungus Glomus intraradices during mycorrhizal association with carrot or Medicago truncatula roots. These analyses reveal that GiPT expression is regulated in response to phosphate concentrations in the environment surrounding the extra-radical hyphae and modulated by the overall phosphate status of the mycorrhiza. Phosphate concentrations, typical of those found in the soil solution, result in expression of GiPT. These data imply that G. intraradices can perceive phosphate levels in the external environment but also suggest the presence of an internal phosphate sensing mechanism.
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Pešková, V. "Dynamics of oak mycorrhizas." Journal of Forest Science 51, No. 6 (January 10, 2012): 259–67. http://dx.doi.org/10.17221/4562-jfs.
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A decline of macromycetes, especially of ectomycorrhizal species, has been described in the last decade in various parts of Europe. These changes are attributed to direct or indirect effects of air pollution. In Central Europe these changes correlate with visual damage of forest. Many ectomycorrhizal fungi seem to be very suitable bioindicators of the disturbance of forest ectotrophic stability. Stages of this disturbance can be linked directly to particular phases of impoverishment of ectomycorrhizal mycocoenoses. These conclusions have been obtained from long-term research on permanent plots (1,000–2,500 m<sup>2</sup>) in spruce and oak forests in the Czech Republic, but it seems that they are valid generally. For the quantification and study of mycorrhizal activity a special method has been developed and applied. The analyses of mycorrhizas from the same plots in the period 2000–2002 indicate large mycorrhizal dynamics. These data correlate with data obtained from a fruiting bodies survey. Both the percentage of ectomycorrhizal species and the ratio of active mycorrhizas are highly sensitive to outer impacts (air pollution, acidification, fertilization). Their decrease is in correlation with the strong defoliation of trees and can be used for the prediction of further development in comparable stands.
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Allen, WK, WG Allaway, GC Cox, and PG Valder. "Ultrastructure of Mycorrhizas of Dracophyllum secundum R. Br. (Ericales:Epacridaceae)." Functional Plant Biology 16, no. 1 (1989): 147. http://dx.doi.org/10.1071/pp9890147.
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Dracophyllum secundum R. Br. (Epacridaceae) often possessed ericoid mycorrhizas; fungal endophytes formed coils within cells of the epidermis of hair-roots. The plant plasma membrane extended around the hyphae. In some epidermal cells of hair-roots, both plant and fungal cells retained their structural integrity, both partners showing mitochondrial, vacuolar and lipid droplet profiles, and with much of the plant cytoplasm associated with the hyphal coils. In other epidermal cells of hair-roots, fungal coils were present but cytoplasmic features of both symbionts appeared to have broken down. Some epidermal cells showed no evidence of fungal infection. These three arrangements could occur in root-cells of the same age, and are interpreted as resulting from different stages in the development and degeneration of the infection by the mycorrhizal fungus. Two structural types of fungal endophyte here found in ericoid mycorrhizas in D. secundum: one with simple septa, Woronin bodies and two-layered walls (presumed to be an Ascomycete), and another with dolipore septa with imperforate parenthesomes (presumed to be a Basidiomycete). The possibilities that the mycorrhizas may be seasonal, and that mycorrhizal status varies from place to place, are discussed.
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MOLDOVAN, Victoria POP, Roxana VIDICAN, Larisa CORCOZ, and Vlad STOIAN. "Mycorrhizal Role in Phosphorus Metabolism." Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Agriculture 79, no. 1 (May 14, 2022): 1. http://dx.doi.org/10.15835/buasvmcn-agr:2022.0006.
Full textAbstract:
The roots of the plants are in contact with a substrate, and biotic and abiotic factors influence their functioning and development. The most known microorganisms associated with plant roots are soil fungi, which are adapted to the soil's living environment, called mycorrhizae. Arbuscular mycorrhizae are the most common of these associations. In agricultural ecosystems, the constant use of technologies has resulted in a progressive reduction of mycorrhizal diversity. Due to this phenomenon, soil presents a lower potential for the development of multi-level hyphal networks which implies reduced connections between all individuals of a single species. Mycorrhizas offer benefits for the host plant, including mineral nutrition, increased drought tolerance, and protection against pathogens. They play a significant role in acquiring the necessary nutrients (especially phosphorus and nitrogen) from soil to their host plants, as these nutrients may have low mobility in most soils. Plants take up phosphorus from soil indirectly through the hyphal network that can reach outside from the root depletion area. Mycorrhizal association increases the accumulation of nitrogen in the plant as a result of the competition of hyphae for the organic mineralized form of this element.
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POP MOLDOVAN, Victoria, Roxana VIDICAN, Larisa CORCOZ, and Vlad STOIAN. "Highlighting Mycorrhizal Structures in Roots of Zea mays L." Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Agriculture 79, no. 1 (May 14, 2022): 21. http://dx.doi.org/10.15835/buasvmcn-agr:2022.0007.
Full textAbstract:
Agriculture is one of the key economic activities designed to provide food for a growing population. It is expected that 21st-century agriculture will try to reduce the number of fertilizers by using microorganisms, in this category arbuscular mycorrhizas representing a complex set of benefits for plants and ecosystem services. The aim of this paper is to identify the mycorrhizal structures present in the roots of Zea mays. The objectives of the research are: i) are mycorrhizae natively present in the corn root and have a constant presence from the first stages of plant development? and ii) what kind of colonization pattern is characteristic of these roots? Maize has prominent fasciculate roots, and due to its intense branching capacity provides increased biological support for the establishment of mycorrhizal symbionts. Within the fungal structures highlighted, the most prominent were arbuscules and vesicles. Arum-type arbuscules were mostly observed, Paris-type arbuscules being less common in this species. Vesicles have a low frequency in the root cortex. They are present only in the early stages of plant development. Vesicular-arbuscular mycorrhizae are present in the root of the Zea mays plant with a constant presence, without major fluctuations.
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Whipps, John M. "Prospects and limitations for mycorrhizas in biocontrol of root pathogens." Canadian Journal of Botany 82, no. 8 (August 1, 2004): 1198–227. http://dx.doi.org/10.1139/b04-082.
Full textAbstract:
More than 80 disease biocontrol products are on the market worldwide, but none of these contain mycor rhizal fungi. This is despite ample evidence that both arbuscular mycorrhizal fungi and ectomycorrhizal fungi can control a number of plant diseases. A procedure for successful development of disease biocontrol agents in general is used as a background to examine the potential for achieving commercial mycorrhizal biocontrol agents. This includes (i) selection and screening; (ii) characterization involving identification, studies of modes of action and ecophysiology, as well as inoculum production, formulation, application and shelf life; (iii) registration. The last stage is problematic for mycorrhizal fungi, as currently they can be sold as plant growth promoters without any form of costly registration, even though in some instances they may actually function to some extent through biocontrol activity. The significance of this approach is discussed, and some possible ways of enhancing biocontrol by mycorrhizas are considered.Key words: arbuscular mycorrhizas, ectomycorrhizas, biological disease control, soilborne pathogens, modes of action, ecology.
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Rimington, William R., Silvia Pressel, Jeffrey G. Duckett, Katie J. Field, David J. Read, and Martin I. Bidartondo. "Ancient plants with ancient fungi: liverworts associate with early-diverging arbuscular mycorrhizal fungi." Proceedings of the Royal Society B: Biological Sciences 285, no. 1888 (October 10, 2018): 20181600. http://dx.doi.org/10.1098/rspb.2018.1600.
Full textAbstract:
Arbuscular mycorrhizas are widespread in land plants including liverworts, some of the closest living relatives of the first plants to colonize land 500 million years ago (MYA). Previous investigations reported near-exclusive colonization of liverworts by the most recently evolved arbuscular mycorrhizal fungi, the Glomeraceae, indicating a recent acquisition from flowering plants at odds with the widely held notion that arbuscular mycorrhizal-like associations in liverworts represent the ancestral symbiotic condition in land plants. We performed an analysis of symbiotic fungi in 674 globally collected liverworts using molecular phylogenetics and electron microscopy. Here, we show every order of arbuscular mycorrhizal fungi colonizes early-diverging liverworts, with non-Glomeraceae being at least 10 times more common than in flowering plants. Arbuscular mycorrhizal fungi in liverworts and other ancient plant lineages (hornworts, lycopods, and ferns) were delimited into 58 taxa and 36 singletons, of which at least 43 are novel and specific to liverworts. The discovery that early plant lineages are colonized by early-diverging fungi supports the hypothesis that arbuscular mycorrhizas are an ancestral symbiosis for all land plants.
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Quirk, Joe, David J. Beerling, Steve A. Banwart, Gabriella Kakonyi, Maria E. Romero-Gonzalez, and Jonathan R. Leake. "Evolution of trees and mycorrhizal fungi intensifies silicate mineral weathering." Biology Letters 8, no. 6 (August 2012): 1006–11. http://dx.doi.org/10.1098/rsbl.2012.0503.
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Forested ecosystems diversified more than 350 Ma to become major engines of continental silicate weathering, regulating the Earth's atmospheric carbon dioxide concentration by driving calcium export into ocean carbonates. Our field experiments with mature trees demonstrate intensification of this weathering engine as tree lineages diversified in concert with their symbiotic mycorrhizal fungi. Preferential hyphal colonization of the calcium silicate-bearing rock, basalt, progressively increased with advancement from arbuscular mycorrhizal (AM) to later, independently evolved ectomycorrhizal (EM) fungi, and from gymnosperm to angiosperm hosts with both fungal groups. This led to ‘trenching’ of silicate mineral surfaces by AM and EM fungi, with EM gymnosperms and angiosperms releasing calcium from basalt at twice the rate of AM gymnosperms. Our findings indicate mycorrhiza-driven weathering may have originated hundreds of millions of years earlier than previously recognized and subsequently intensified with the evolution of trees and mycorrhizas to affect the Earth's long-term CO 2 and climate history.
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Khan, A. G. "The Occurrence of Mycorrhizas in Halophytes, Hydrophytes and Xerophytes, and of Endogone Spores in Adjacent Soils." Microbiology 81, no. 1 (January 1, 2000): 7–14. http://dx.doi.org/10.1099/00221287-81-1-7.
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The incidence of mycorrhizas in the roots and Endogone spores in rhizosphere soil of 52 xerophytes, 21 halophytes and 16 hydrophytes from Pakistan was investigated. Vesicular-arbuscular mycorrhizas were of general occurrence in all plants examined except hydrophytes and members of the families Urticaceae, Casuarinaceae, Nyctaginaceae, Portulaceae, Caryophyllaceae, Amaranthaceae, Chenopodiaceae, Capparaceae, Oleaceae, Elaeagnaceae, Zygophyllaceae, Tamaricaceae, Euphorbiaceae and Palmae. Mycorrhizas were found mainly in the surface and subsurface horizons of the soil, and they were much less abundant in the deeper layers, although the abundance of Endogone spores did not decrease with depth. Endogone spores were rare in permanently waterlogged soils, which suggested that soil moisture affected spore number. Most other soil samples contained Endogone spores, including some from rhizospheres of non-mycorrhizal plants. In some soils an increase in spore numbers was recorded in the autumn and winter and a decrease in the spring and summer.
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Zelmer, Carla D., and R. S. Currah. "Ceratorhiza pernacatena and Epulorhiza calendulina spp.nov.: mycorrhizal fungi of terrestrial orchids." Canadian Journal of Botany 73, no. 12 (December 1, 1995): 1981–85. http://dx.doi.org/10.1139/b95-212.
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Two new species of fungi mycorrhizal with terrestrial orchids native to the Canadian prairies are described and illustrated. Ceratorhiza pernacatena sp.nov., from mycorrhizas of Platanthera praeclara, produces globose monilioid cells linked by narrow, tubular, connections that contain the septum between adjacent cells. Hyphae are binucleate, 5–7 μm in width, regularly septate with perforate parenthesomes. Cellulase is produced, but polyphenol oxidase production is low to absent. Epulorhiza calendulina sp.nov., from mycorrhizas of Amerorchis rotundifolia, is distinguished from other Epulorhiza species by the orange to ochre colour of colonies on potato dextrose agar. On corn meal agar, clavate to irregular monilioid cells are produced in short, branched, chains arising from lateral hyphal branches. Runner hyphae are binucleate, 3.0–4.7 μm in width, regularly septate, with flattened, imperforate parenthesomes. Polyphenol oxidase production is lacking, but cellulase is produced. Key words: orchid mycorrhizas, Amerorchis rotundifolia, Platanthera praeclara, Rhizoctonia.
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Vidican, Roxana, Ioan Rotar, Vlad Stoian, and Florin Păcurar. "Influence of Phosphorus and Nitrogen on Mycorrhizas in Winter Wheat." Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Agriculture 73, no. 2 (November 30, 2016): 357. http://dx.doi.org/10.15835/buasvmcn-agr:12397.
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Intraradicular installation of vesicular-arbuscular mycorrhizas on the roots acts to amplify growth and to increase potential yield. Extraradicular network of hyphae developed by mycorrhizas acts as an extension of the root in order to access the nutrients located in unexplored areas. The percentage of roots occupied by mycorrhizal hyphae fluctuates heavily under the influence of fertilization. The highest values of the colonization parameters were recorded with a high level of phosphorus fertilization applied as phasial input. High doses of mineral fertilizers with phosphorus applied with seeding favors the development intraradicular hyphal networks in wheat roots.
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Reed, ML. "Ericoid Mycorrhizas of Styphelieae: Intensity of Infection and Nutrition of the Symbionts." Functional Plant Biology 16, no. 1 (1989): 155. http://dx.doi.org/10.1071/pp9890155.
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Soil and leaf total nitrogen and intensity of ericoid mycorrhizal infection were measured in Leucopogon juniperinus R.Br. growing under forest in four different soils. Leaf nitrogen varied from 1.1 to 1.9%, which was correlated with soil nitrogen (0.17-0.32%) but was not related to intensity of infection. Maximal infection occurred in March and the cold months. Five vegetative types of endophytes were isolated from roots of L. juniperinus. Three produced ericoid mycorrhizas in pot cultures of Vaccinium. A fungus isolated from a decaying endocarp of Styphelia tubiflora Sm. produced an infection in Vaccinium which was similar to ericoid mycorrhizas.
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McGee, Peter, Greg Pattinson, and Anne-Laure Markovina. "Mycorrhizas and revegetation." Microbiology Australia 24, no. 3 (2003): 32. http://dx.doi.org/10.1071/ma03332.
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Much of Australia has extremely impoverished soil. Phosphate is particularly deficient. The major difficulty in revegetating these soils after severe disturbance is that plant survival and growth is unpredictable. Mycorrhizas are associations between soilborne fungi and the roots of plants. Of particular interest are the arbuscular mycorrhiza (AM) whose fungi form an internal colony in the roots of some 70% of all plant species. In AM, the fungi function as extensions of the root system, enabling the plant to increase uptake of non-labile minerals, especially phosphorus (P), from soil. The fungus gains its organic energy from the plant, and can only be maintained in the presence of living roots.
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Mcgee, PA, and JH Furby. "Formation and Structure of Mycorrhizas of Seedlings of Coachwood (Ceratopetalum apetalum)." Australian Journal of Botany 40, no. 3 (1992): 291. http://dx.doi.org/10.1071/bt9920291.
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The mycorrhizas of seedlings of coachwood (Ceratopetalum apetalum) were examined. When the host was grown under increased photon flux density infections of both vesicular-arbuscular (VA) and a sheathing association were extended. Paris type VA mycorrhizas were observed, though arbuscules and vesicles were rare. Hyphae of VA mycorrhizal fungi appeared to degenerate when under the sheathing association. The sheathing association was characterised by thin mantles and no Hartig net. An electron-dense bilayer formed over hyphae in the sheath and hyphae were surrounded by a fibrillar matrix. Beneath the sheath, the walls of the epidermis were thickened and fibrillar. Lignin and suberin were present in the walls of cells of the hypodermis and absent in the epidermis. No evidence was found that the fungal associations induced a negative response from the host. While the structure of the mycorrhizas was unusual, the sheathing association was believed to be a variant of typical ectomycorrhizas.
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Frymark-Szymkowiak, Anna, Magdalena Kulczyk-Skrzeszewska, and Jolanta Tyburska-Woś. "Seasonal Dynamics in Mycorrhizal Colonization and Fine Root Features of the White Poplar (Populus alba L.) in Natural Temperate Riverside Forests with Two Contrasting Soils." Forests 15, no. 1 (December 28, 2023): 64. http://dx.doi.org/10.3390/f15010064.
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Fine roots are the most dynamic and physiologically active components of belowground tree organs. However, much remains unknown regarding the changes in fine root morphological characteristics during mycorrhizal colonization, especially in natural sites. The aim of this study was to analyze seasonal heterogeneity in fine roots and the mycorrhizal colonization of mature white poplar (Populus alba L.) trees under different soil conditions. Two floodplain forests were selected in Central Europe (Poland), which differed in soil moisture and structure. Fine roots were sampled during one growing season from the upper soil layer. Poplars were characterized by dual mycorrhizal colonization on one root system. It was, therefore, possible to investigate the contribution of two mycorrhizal types (arbuscular mycorrhiza—AM; and ectomycorrhiza—ECM) in response to different habitat conditions. The season was shown to be significant for all fine root features, as well as the degree of mycorrhizal colonization. Roots were better adapted to a drier habitat with a greater proportion of sand, mainly due to a reduction in the fine root diameter (FRD), while other root characteristics did not differ significantly. The degree of mycorrhizal colonization (RLC) and the proportion of arbuscular mycorrhizal structures (AM) were significantly and negatively correlated with the soil water content. A mutual competition between arbuscular mycorrhizas and ectomycorrhizas for poplar roots was also observed, particularly with respect to the season, site, and soil moisture. Changing environmental conditions (especially soil moisture) contribute not only to the morphological and functional changes of fine roots but also to changes in the proportion of arbuscular mycorrhiza and ectomycorrhiza. Understanding the mechanisms of adaptation of tree roots to changing environmental conditions is especially important in the context of climate change.
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CORCOZ, Larisa, Roxana VIDICAN, Victoria POP-MOLDOVAN, and Vlad STOIAN. "Highlighting the Structures and Patterns of Fungal Colonization in the Species Festuca rubra." Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Agriculture 79, no. 1 (May 14, 2022): 7. http://dx.doi.org/10.15835/buasvmcn-agr:2022.0008.
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Grasslands are the most dynamic ecosystems are characterized by high biodiversity both above-ground and underground. The biggest problem in these ecosystems is oligotrophy. The phenomenon affects the stability and resilience of these ecosystems, increasing the impact of biological processes. The symbiotic relationship between plants and mycorrhizas is a natural option with a great impact on maintaining the high natural value of ecosystems. This article aims rating colonization Festuca rubra, dominant in a mountain grassland ecosystem. Roots were cleared and stained with ink for the detection of mycorrhizas in roots. All root samples were analyzed with an optical microscope for the detection of mycorrhizal structures. The results obtained highlight a main mycorrhizal pattern as well as specific subcategories. Both types of arbuscules were identified: Arum and Paris. The results obtained highlight a main mycorrhizal pattern as well as specific subcategories. Vesicles are structures with a constant lack of consistency, which indicates their fluctuating nature. The mycorrhizal pattern of Festuca rubra as the dominant species in the pratol ecosystem may be the first step towards a more detailed understanding of the fungal strategy as well as the increased importance in the stability of the pratol ecosystem.
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Asghari, Hamid Reza, and Timothy Richard Cavagnaro. "Arbuscular mycorrhizas enhance plant interception of leached nutrients." Functional Plant Biology 38, no. 3 (2011): 219. http://dx.doi.org/10.1071/fp10180.
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Arbuscular mycorrhizal fungi (AMF) can increase plant growth and nutrition. However, their capacity to reduce the leaching of nutrients through the soil profile is less well understood. Here we present results of an experiment in which the effects of forming arbuscular mycorrhizas (AM) on plant growth and nutrition, nutrient depletion from soil, and nutrient leaching, were investigated in microcosms containing the grass Phalaris aquatica L. Mycorrhizal and non-mycorrhizal plants were grown in a mixture of riparian soil and sand under glasshouse conditions. The formation of AM by P. aquatica significantly increased plant growth and nutrient uptake. Lower levels of NO3–, NH4+ and plant available P in both soil and leachate were observed in columns containing mycorrhizal root systems. These differences in nutrient interception were proportionally greater than the increase in root biomass of the mycorrhizal plants, compared with their non-mycorrhizal counterparts. Taken together, these data indicate that mycorrhizal root systems have an important, but previously little considered, role to play reducing the net loss of nutrients via leaching.