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Assembly of Root-associated Fungi in Different Soil Layers and Nitrogen Uptake by Ectomycorrhizae in Temperate Forests

2021
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Release : 2021
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Book Synopsis Assembly of Root-associated Fungi in Different Soil Layers and Nitrogen Uptake by Ectomycorrhizae in Temperate Forests by : Anis Mahmud Khokon

Download or read book Assembly of Root-associated Fungi in Different Soil Layers and Nitrogen Uptake by Ectomycorrhizae in Temperate Forests written by Anis Mahmud Khokon. This book was released on 2021. Available in PDF, EPUB and Kindle. Book excerpt: Fungi are a remarkably highly diverse group of organisms on Earth, playing a pivotal role in ecosystem functioning. Belowground, they act as decomposers, pathogens or symbionts. Members of these functional categories are colonizing roots and have been defined as root-associated fungi. The abundance and distribution patterns of fungal communities are determined by various environmental factors, including soil and root properties, vegetation and climatic conditions. Soil fungal communities are known to be vertically stratified across different soil layers but our knowledge about root-associat...

Diversity and Function of Root-associated Fungal Communities in Relation to Nitrogen Nutrition in Temperate Forests

2019
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Release : 2019
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Book Synopsis Diversity and Function of Root-associated Fungal Communities in Relation to Nitrogen Nutrition in Temperate Forests by : Quang Dung Nguyen

Download or read book Diversity and Function of Root-associated Fungal Communities in Relation to Nitrogen Nutrition in Temperate Forests written by Quang Dung Nguyen. This book was released on 2019. Available in PDF, EPUB and Kindle. Book excerpt: Ectomycorrhizal fungi form symbiotic association with roots of a variety of plant species. They provide plants with nutrients in exchange of photosynthetic carbohydrates. In natural ecosystems, plants form associations not only with ectomycorrhizal fungi but also with a variety of other microbes. Interest in root-associated fungal communities is increasing because they may play an important role in plant nutrition and fitness. Nitrogen (N) is an essential nutrient for plant growth and development but often a limiting factor in forest ecosystems. To date, little is known on the relationship ...

Nitrogen Form Uptake Capacities by Arbuscular Mycorrhizae and Ectomycorrhizae

2017
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Release : 2017
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Book Synopsis Nitrogen Form Uptake Capacities by Arbuscular Mycorrhizae and Ectomycorrhizae by : Ramnique Ubhi

Download or read book Nitrogen Form Uptake Capacities by Arbuscular Mycorrhizae and Ectomycorrhizae written by Ramnique Ubhi. This book was released on 2017. Available in PDF, EPUB and Kindle. Book excerpt: Plant growth and survival are affected by the nutrients available in the environment. Nitrogen (N) is most often the limiting nutrient in terrestrial ecosystems, particularly in temperate and boreal forests, such as those on Vancouver Island. To overcome the challenge of limited nutrient availability, plants have evolved symbiotic relationships with fungi, called mycorrhizae. While research on the importance of mycorrhizal symbioses for N uptake by plants continues to grow, we have a limited understanding of the mechanisms of N uptake and transfer by mycorrhizae. This knowledge is crucial to fully understand N uptake and assimilation by plants. This study aimed to determine the influence of soil N availability on conifer growth and foliar N content, and on the N form preferences and sporocarp N content of associated mycorrhizae. Inorganic and organic soil N production was determined for two sites, Fairy Lake and San Juan, near Port Renfrew British Columbia, under pure plantations of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco), Sitka spruce (Picea sitchensis [Bong.] Carr.), western redcedar (Thuja plicata Donn ex D. Don in Lamb) and western hemlock (Tsuga heterophylla [Raf.] Sarg.). Ammonium, nitrate and amino acid production contrasted between the sites, with relatively higher N production in San Juan compared to Fairy Lake. This indicated differences in soil N cycling, most likely due to differences in moisture and topography. In general, conifer species did not affect inorganic and organic soil N production. Growth of conifers increased with increasing N availability, and differed between species, with Douglas-fir and Sitka spruce having the greatest growth and western redcedar having the least growth. Foliar %N and 15N were found to differ among the conifer species, and western redcedar had the lowest foliar N concentrations. While site quality was not reflected in foliar %N, foliar 15N was found to increase with increasing 15N of the forest floor. Ectomycorrhizal (ECM) sporocarps reflected site quality, with greater N concentrations but lower 15N values on the higher N site. Sporocarp 15N concentrations were higher than foliar 15N concentrations, suggesting N isotope fractionation by mycorrhizae. Finally, site N availability was not related to the rates of N form uptake by ECM genera. Both ECM and arbuscular mycorrhizae (AM) did not have substantial nitrate uptake, despite a greater supply of nitrate. Ammonium was found to be taken up at higher rates than nitrate in the ECM and AM roots, suggesting a preference for ammonium, possibly due to ammonium being energetically cheaper to metabolize and suppressing nitrate transporters in mycorrhizal fungi. Differences in proportions of N form uptake and sporocarp N content among ECM genera were seen, indicating potential niche formation based on functional traits such as N form uptake and mycelial morphology. Knowing how mycorrhizae respond to different N forms and rates of N supply will not only increase our knowledge of N dynamics in mycorrhizal symbioses, but will help predict the effects environmental changes, such as disturbance and N deposition, may have on these systems.

Nutrient Availability Does Not Affect Community Assembly in Root-associated Fungi But Determines Fungal Effects on Plant Growth

2022
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Release : 2022
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Book Synopsis Nutrient Availability Does Not Affect Community Assembly in Root-associated Fungi But Determines Fungal Effects on Plant Growth by : Jose G. Maciá-Vicente

Download or read book Nutrient Availability Does Not Affect Community Assembly in Root-associated Fungi But Determines Fungal Effects on Plant Growth written by Jose G. Maciá-Vicente. This book was released on 2022. Available in PDF, EPUB and Kindle. Book excerpt: Nonmycorrhizal root-colonizing fungi are key determinants of plant growth, driving processes ranging from pathogenesis to stress alleviation. Evidence suggests that they might also facilitate host access to soil nutrients in a mycorrhiza-like manner, but the extent of their direct contribution to plant nutrition is unknown. To study how widespread such capacity is across root-colonizing fungi, we surveyed soils in nutrient-limiting habitats using plant baits to look for fungal community changes in response to nutrient conditions. We established a fungal culture collection and used Arabidopsis thaliana inoculation bioassays to assess the ability of fungi to facilitate host's growth in the presence of organic nutrients unavailable to plants. Plant baits captured a representation of fungal communities extant in natural habitats and showed that nutrient limitation has little influence on community assembly. Arabidopsis thaliana inoculated with 31 phylogenetically diverse fungi exhibited a consistent fungus-driven growth promotion when supplied with organic nutrients compared to untreated plants. However, direct phosphorus measurement and RNA-seq data did not support enhanced nutrient uptake but rather that growth effects may result from changes in the plant's immune response to colonization. The widespread and consistent host responses to fungal colonization suggest that distinct, locally adapted nonmycorrhizal fungi affect plant performance across habitats. IMPORTANCE: Recent studies have shown that root-associated fungi that do not engage in classical mycorrhizal associations can facilitate the hosts' access to nutrients in a mycorrhiza-like manner. However, the generality of this capacity remains to be tested. Root-associated fungi are frequently deemed major determinants of plant diversity and performance, but in the vast majority of cases their ecological roles in nature remain unknown. Assessing how these plant symbionts affect plant productivity, diversity, and fitness is important to understanding how plant communities function. Recent years have seen important advances in the understanding of the main drivers of the diversity and structure of plant microbiomes, but a major challenge is still linking community properties with function. This study contributes to the understanding of the cryptic function of root-associated fungi by testing their ability to participate in a specific process: nutrient acquisition by plants.

Association of Nitrogen-fixing Bacteria with Ectomycorrhizae in Douglas-fir

1987 Douglas fir
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Release : 1987
Genre : Douglas fir
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Book Synopsis Association of Nitrogen-fixing Bacteria with Ectomycorrhizae in Douglas-fir by : Chih-hao Niu

Download or read book Association of Nitrogen-fixing Bacteria with Ectomycorrhizae in Douglas-fir written by Chih-hao Niu. This book was released on 1987. Available in PDF, EPUB and Kindle. Book excerpt: Many higher plants have mycorrhizae associated with their roots. These structures are often essential for survival and growth (Harley & Smith 1983). Mycorrhizae are known for the abilities to enhance nutrient absorption. While nitrogen-fixing organisms are found as components of the mycorrhizosphere, mycorrhizal fungi are not presently known to fix nitrogen (Trappe & Fogel 1977). The role of mycorrhizal fungi in nitrogen fixation in the rhizosphere was explored in this study. The objectives were (1) to determine if nitrogen fixation is occurring in the rhizosphere of the Douglas-fir ectomycorrhizae formed with Hysterangiufli setchelli Fischer and Gautieria monticola Harkness in the Woods Creek area of Mary's Peak, Oregon; (2) to determine seasonal changes in nitrogen fixation and in populations of nitrogenfixing bacteria; (3) to isolate and identify nitrogen-fixing bacteria associated with ectomycorrhizae. The samples were collected each month from October 1985 to September 1986. Nitrogen fixation (acetylene reduction activity) was significantly higher each month in the mycorrhizosphere of the Douglas-fir than in the non-mat soil controls. Change in acetylene reduction rate with log-transformed incubation time was adequately expressed by a straight-line relationship. The average nitrogenase activities associated with H. setchelli and G. monticola were 1.36 and 1.44 nmoles/g/day, whereas the activity recorded for the non-mat soil controls was 0.38 nmoles/g/day. Acetylene reduction activity was significantly higher in spring, fall, and winter than in sumer, but the activity during spring, fall, and winter did not differ from each other. Nitrogen-fixing bacteria associated with mycorrhizae were also estimated by the most probable number methods. Nitrogenfixing populations showed considerable variability from month to month. However, some of them (those in March, August, September) showed a similar trend to acetylene reduction activities. Three different nitrogen-fixing bacteria were isolated from the fungal sheaths of H. setchelli, G. monticola, and within the sporocarps of H. setchelli. The three different strains showed a characteristic spiral movement when observed in H20 using light microscopy. Cells are straight to curved, plump, and slightly pointed with phase-dense granules. They grew well on nutrient agar and could reduce C2H2 on Dobereiner's N-free medium under micro-aerophilic conditions. On the basis of the findings of Tarrand et al. (1978), these strains probably are strains of Azospiril lum brasilense. The potential of nitrogen-fixing bacteria associated with coniferous ectomycorrhizal roots and their associated fungal sporocarps is of considerable importance to foresters. The N2- fixer could be selected for inoculation so that it utilized the protective and nutritional advantage of the mycorrhizae. These discoveries open exciting possibilities for understanding the role of mycorrhizae in nitrogen cycling and developing information on how management practices might be modified to optimize biological nitrogen fixation in the rhizosphere of young-growth Douglas-fir.

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