scholarly journals Common Mycorrhizae Network: A Review of the Theories and Mechanisms Behind Underground Interactions

2021 ◽  
Vol 2 ◽  
Author(s):  
Aline Fernandes Figueiredo ◽  
Jens Boy ◽  
Georg Guggenberger
Keyword(s):  
Mycorrhizal Fungi ◽  
Host Plants ◽  
Physiological Responses ◽  
Plant Fitness ◽  
Plant Interactions ◽  
Terrestrial Plants ◽  
Symbiotic Associations ◽  
Open Questions ◽  
Mycelial Network ◽  
Mutant Lines

Most terrestrial plants establish symbiotic associations with mycorrhizal fungi for accessing essential plant nutrients. Mycorrhizal fungi have been frequently reported to interconnect plants via a common mycelial network (CMN), in which nutrients and signaling compounds can be exchanged between the connected plants. Several studies have been performed to demonstrate the potential effects of the CMN mediating resource transfer and its importance for plant fitness. Due to several contrasting results, different theories have been developed to predict benefits or disadvantages for host plants involved in the network and how it might affect plant communities. However, the importance of the mycelium connections for resources translocation compared to other indirect pathways, such as leakage of fungi hyphae and subsequent uptake by neighboring plant roots, is hard to distinguish and quantify. If resources can be translocated via mycelial connections in significant amounts that could affect plant fitness, it would represent an important tactic for plants co-existence and it could shape community composition and dynamics. Here, we report and critically discuss the most recent findings on studies aiming to evaluate and quantify resources translocation between plants sharing a CMN and predict the pattern that drives the movement of such resources into the CMN. We aim to point gaps and define open questions to guide upcoming studies in the area for a prospect better understanding of possible plant-to-plant interactions via CMN and its effect in shaping plants communities. We also propose new experiment set-ups and technologies that could be used to improve previous experiments. For example, the use of mutant lines plants with manipulation of genes involved in the symbiotic associations, coupled with labeling techniques to track resources translocation between connected plants, could provide a more accurate idea about resource allocation and plant physiological responses that are truly accountable to CMN.

scholarly journals Beneficial soil-borne bacteria and fungi: a promising way to improve plant nitrogen acquisition

2020 ◽  
Vol 71 (15) ◽  
pp. 4469-4479 ◽  
Author(s):  
Alia Dellagi ◽  
Isabelle Quillere ◽  
Bertrand Hirel
Keyword(s):  
Mycorrhizal Fungi ◽  
Current Knowledge ◽  
Essential Element ◽  
Symbiotic Association ◽  
Terrestrial Plants ◽  
Plant Nitrogen ◽  
N Nutrition ◽  
Symbiotic Associations ◽  
N Fertilizers ◽  
Bacteria And Fungi

Abstract Nitrogen (N) is an essential element for plant productivity, thus, it is abundantly applied to the soil in the form of organic or chemical fertilizers that have negative impacts on the environment. Exploiting the potential of beneficial microbes and identifying crop genotypes that can capitalize on symbiotic associations may be possible ways to significantly reduce the use of N fertilizers. The best-known example of symbiotic association that can reduce the use of N fertilizers is the N2-fixing rhizobial bacteria and legumes. Bacterial taxa other than rhizobial species can develop associative symbiotic interactions with plants and also fix N. These include bacteria of the genera Azospirillum, Azotobacter, and Bacillus, some of which are commercialized as bio-inoculants. Arbuscular mycorrhizal fungi are other microorganisms that can develop symbiotic associations with most terrestrial plants, favoring access to nutrients in a larger soil volume through their extraradical mycelium. Using combinations of different beneficial microbial species is a promising strategy to boost plant N acquisition and foster a synergistic beneficial effect between symbiotic microorganisms. Complex biological mechanisms including molecular, metabolic, and physiological processes dictate the establishment and efficiency of such multipartite symbiotic associations. In this review, we present an overview of the current knowledge and future prospects regarding plant N nutrition improvement through the use of beneficial bacteria and fungi associated with plants, individually or in combination.

scholarly journals Suppression of fungal and nematode plant pathogens through arbuscular mycorrhizal fungi

2011 ◽  
Vol 8 (2) ◽  
pp. 214-217 ◽  
Author(s):  
Stavros D. Veresoglou ◽  
Matthias C. Rillig
Keyword(s):  
Mycorrhizal Fungi ◽  
Fungal Pathogens ◽  
Host Plants ◽  
Plant Pathogens ◽  
Meta Analysis ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Terrestrial Plants ◽  
Pathogen Suppression ◽  
Mycorrhizal Ecology

Arbuscular mycorrhizal (AM) fungi represent ubiquitous mutualists of terrestrial plants. Through the symbiosis, plant hosts, among other benefits, receive protection from pathogens. A meta-analysis was conducted on 106 articles to determine whether, following pathogen infection of AM-colonized plants, the identity of the organisms involved (pathogens, AM fungi and host plants) had implications for the extent of the AM-induced pathogen suppression. Data on fungal and nematode pathogens were analysed separately. Although we found no differences in AM effectiveness with respect to the identity of the plant pathogen, the identity of the AM isolate had a dramatic effect on the level of pathogen protection. AM efficiency differences with respect to nematode pathogens were mainly limited to the number of AM isolates present; by contrast, modification of the ability to suppress fungal pathogens could occur even through changing the identity of the Glomeraceae isolate applied. N-fixing plants received more protection from fungal pathogens than non-N-fixing dicotyledons; this was attributed to the more intense AM colonization in N-fixing plants. Results have implications for understanding mycorrhizal ecology and agronomic applications.

scholarly journals Mycorrhiza-improved P acquisition of host plants: A mini-review

2021 ◽  
Vol 14 (3) ◽  
pp. 062-067
Author(s):  
Guang-Ming Huang ◽  
Yong-Jie Xu ◽  
Qiang-Sheng Wu
Keyword(s):  
Mycorrhizal Fungi ◽  
Host Plants ◽  
Phosphorus Uptake ◽  
Arbuscular Mycorrhizal ◽  
Plant Roots ◽  
Future Research ◽  
Terrestrial Plants ◽  
Transporter Protein ◽  
P Acquisition ◽  
Genes Expression

As a beneficial endophytic fungus, arbuscular mycorrhizal fungi (AMF) are widely distributed in nature and can symbiotically grow with approx. 80% of terrestrial plants, helping host plants to grow and develop with increased tolerance to various stresses. One of the most important functions of AMF is to promote the uptake of P from the soil by the host plant. The available findings explain the role of mycorrhizal fungi. For example, AMF increase the phosphorus uptake area of plant roots by improving the root architecture, and the extraradical mycelium can extend beyond the phosphorus-deprived areas that are inaccessible to the root, helping to expand new phosphorus sources. AMF also increase the secretion of phosphatases and organic acids in plant roots to improve the soil environment for accelerating the conversion of insoluble phosphorus. The phosphorus transporter protein genes expression is induced by AMF to enhance host P acquisition. The review briefly outlines these potential mechanisms and suggests outlooks for future research.

Mycorrhizas and nutrient cycling in sand dune ecosystems

1989 ◽  
Vol 96 ◽  
pp. 89-110 ◽  
Author(s):  
D. J. Read
Keyword(s):  
Organic Matter ◽  
Mycorrhizal Fungi ◽  
Sand Dune ◽  
High Tide ◽  
Experimental Studies ◽  
Phosphate Limitation ◽  
Soil Conditions ◽  
Mycorrhizal Infection ◽  
Symbiotic Associations ◽  
Mycelial Network

SynopsisThe extent of occurrence, the form and the function of mycorrhizal infection are shown to change with successional development across coastal sand dune systems. The interrelationships between these changes and the prevailing physico-chemical conditions are explored and clear patterns are recognised in terms of both type and function of the infection. The periodically disturbed and nutritionally enriched high tide line is colonised by non-mycorrhizal ruderal species. There follows a sequence of plant communities, each characterised by the presence of a dominant mycorrhizal type and a distinctive nutritional limitation. In the foredunes, pioneer grasses are normally infected with vesicular-arbuscular (VA) mycorrhizal fungi. Plants such as Ammophila, Leymus and Uniola, all of which have extensive root systems, appear, when fully grown, to be only facultatively mycorrhizal. However, experimental evidence suggests that infection is important for the early growth of such plants and it is suggested that in these, as in many other dune species, mycorrhizas may be essential at critical stages in the life cycle, most notably during the phase of seedling establishment. Here, phosphorus (P) is the most important growth-limiting nutrient. The extensive mycelial network of VA hyphae not only facilitates capture of this element but also provides the aggregation of sand grains necessary for dune stabilisation. In semi-fixed dune pastures, as sand inputs are reduced, productivities are low and species diversity increased. Phosphate limitation persists and the majority of the characteristic species show VA infection. Experimental studies using microcosms of dune sand containing an assemblage of species typical of such communities suggest that the maintenance of the species richness is dependent upon mycorrhizal fungi which produce a large absorptive mycelial network into which the roots of germinating seedlings become incorporated as they are infected. Accumulation of organic matter in dune-slacks leads to reduction of pH. Nitrification is inhibited, ammonium becomes the major mineral nitrogen (N) source and N replaces P as the key growth-limiting element. Here plants with ecto-mycorrhizal infection predominate. Salix repens produces a shrub layer enriched with litter in which a guild of species interconnected by a common mycorrhizal mycelium occurs. The functional basis of this guild structure is explored, the ability of some of its mycorrhizal fungi to mobilise nutrients from organic macro-molecules being seen as a vital attribute. Where organic matter accumulation and base depletion are most strongly developed in the oldest parts of the succession, plants with ericoid mycorrhizas become important. The ability of their mycorrhizal fungi to liberate N and P from acidic organic complexes, as well as to assimilate or exclude, and hence detoxify, organic acids and metal ions facilitates vigorous growth of ericaceous species in soil conditions which are inimical to plants important earlier in the succession. Since the attributes of each mycorrhizal type are relevant to a specific suite of edaphic properties the formation of appropriate symbiotic associations is likely to be a prerequisite for successional change. It is concluded that mutualism contributes significantly to fitness in the sand dune ecosystems, the further understanding of which will be dependent upon more effective collaboration between the microbiological and ecological disciplines.

scholarly journals The Coevolution of Plants and Microbes Underpins Sustainable Agriculture

2021 ◽  
Vol 9 (5) ◽  
pp. 1036
Author(s):  
Dongmei Lyu ◽  
Levini A. Msimbira ◽  
Mahtab Nazari ◽  
Mohammed Antar ◽  
Antoine Pagé ◽  
...  
Keyword(s):  
Microbial Community ◽  
Plant Growth ◽  
Stress Resistance ◽  
Mycorrhizal Fungi ◽  
Plant Tissues ◽  
Terrestrial Plants ◽  
Plant Host ◽  
Symbiotic Relationships ◽  
Wide Range ◽  
Terrestrial Environments

Terrestrial plants evolution occurred in the presence of microbes, the phytomicrobiome. The rhizosphere microbial community is the most abundant and diverse subset of the phytomicrobiome and can include both beneficial and parasitic/pathogenic microbes. Prokaryotes of the phytomicrobiome have evolved relationships with plants that range from non-dependent interactions to dependent endosymbionts. The most extreme endosymbiotic examples are the chloroplasts and mitochondria, which have become organelles and integral parts of the plant, leading to some similarity in DNA sequence between plant tissues and cyanobacteria, the prokaryotic symbiont of ancestral plants. Microbes were associated with the precursors of land plants, green algae, and helped algae transition from aquatic to terrestrial environments. In the terrestrial setting the phytomicrobiome contributes to plant growth and development by (1) establishing symbiotic relationships between plant growth-promoting microbes, including rhizobacteria and mycorrhizal fungi, (2) conferring biotic stress resistance by producing antibiotic compounds, and (3) secreting microbe-to-plant signal compounds, such as phytohormones or their analogues, that regulate aspects of plant physiology, including stress resistance. As plants have evolved, they recruited microbes to assist in the adaptation to available growing environments. Microbes serve themselves by promoting plant growth, which in turn provides microbes with nutrition (root exudates, a source of reduced carbon) and a desirable habitat (the rhizosphere or within plant tissues). The outcome of this coevolution is the diverse and metabolically rich microbial community that now exists in the rhizosphere of terrestrial plants. The holobiont, the unit made up of the phytomicrobiome and the plant host, results from this wide range of coevolved relationships. We are just beginning to appreciate the many ways in which this complex and subtle coevolution acts in agricultural systems.

scholarly journals A Meta-Analytical Approach on Arbuscular Mycorrhizal Fungi Inoculation Efficiency on Plant Growth and Nutrient Uptake

Agriculture ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 370
Author(s):  
Murugesan Chandrasekaran
Keyword(s):  
Plant Growth ◽  
Arbuscular Mycorrhizal Fungi ◽  
Nutrient Uptake ◽  
Mycorrhizal Fungi ◽  
Host Plants ◽  
Plant Biomass ◽  
Meta Analysis ◽  
Arbuscular Mycorrhizal ◽  
Growth Responses ◽  
Mycorrhizal Plants

Arbuscular mycorrhizal fungi (AMF) are obligate symbionts of higher plants which increase the growth and nutrient uptake of host plants. The primary objective was initiated based on analyzing the enormity of optimal effects upon AMF inoculation in a comparative bias between mycorrhizal and non-mycorrhizal plants stipulated on plant biomass and nutrient uptake. Consequently, in accomplishing the above-mentioned objective a vast literature was collected, analyzed, and evaluated to establish a weighted meta-analysis irrespective of AMF species, plant species, family and functional group, and experimental conditions in the context of beneficial effects of AMF. I found a significant increase in the shoot, root, and total biomass by 36.3%, 28.5%, and, 29.7%, respectively. Moreover, mycorrhizal plants significantly increased phosphorus, nitrogen, and potassium uptake by 36.3%, 22.1%, and 18.5%, respectively. Affirmatively upon cross-verification studies, plant growth parameters intensification was accredited to AMF (Rhizophagus fasciculatus followed by Funniliforme mosseae), plants (Triticum aestivum followed by Solanum lycopersicum), and plant functional groups (dicot, herbs, and perennial) were the additional vital important significant predictor variables of plant growth responses. Therefore, the meta-analysis concluded that the emancipated prominent root characteristics, increased morphological traits that eventually help the host plants for efficient phosphorus uptake, thereby enhancing plant biomass. The present analysis can be rationalized for any plant stress and assessment of any microbial agent that contributes to plant growth promotion.

Warming effects on biomass allocation are jointly regulated by precipitation and mycorrhizal association in terrestrial plants

2021 ◽  
Author(s):  
Xuhui Zhou ◽  
Lingyan Zhou ◽  
Yanghui He ◽  
Yuling Fu ◽  
Zhenggang Du ◽  
...  
Keyword(s):  
Biomass Allocation ◽  
Mycorrhizal Fungi ◽  
Global Scale ◽  
Mean Annual Precipitation ◽  
Shoot Biomass ◽  
Terrestrial Plants ◽  
Terrestrial Carbon ◽  
Shoot Ratio ◽  
Root Shoot Ratio ◽  
Mycorrhizal Association

Abstract Biomass allocation in plants is fundamental for understanding and predicting terrestrial carbon storage. Recent studies suggest that climate warming can differentially affect root and shoot biomass, and subsequently alter root: shoot ratio. However, warming effects on root: shoot ratio and their underlying drivers at a global scale remain unclear. Using a global synthesis of >300 studies, we here show that warming significantly increases biomass allocation to roots (by 13.1%), and two factors drive this response: mean annual precipitation of the site, and the type of mycorrhizal fungi associated with a plant. Warming-induced allocation to roots is greater in relatively drier habitats compared to shoots (by 15.1%), but lower in wetter sites (by 4.9%), especially for plants associated with arbuscular mycorrhizal fungi compared to ectomycorrhizal fungi. Root-biomass responses to warming predominantly determine the biomass allocation in terrestrial plants suggesting that warming can reinforce the importance of belowground resource uptake. Our study highlights that the wetness or dryness of a site and plants’ mycorrhizal associations strongly regulate terrestrial carbon cycle by altering biomass allocation strategies in a warmer world.

scholarly journals The Phosphate Inhibition Paradigm: Host and Fungal Genotypes Determine Arbuscular Mycorrhizal Fungal Colonization and Responsiveness to Inoculation in Cassava With Increasing Phosphorus Supply

2021 ◽  
Vol 12 ◽  
Author(s):  
Ricardo Alexander Peña Venegas ◽  
Soon-Jae Lee ◽  
Moses Thuita ◽  
Deusdedit Peter Mlay ◽  
Cargele Masso ◽  
...  
Keyword(s):  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizal ◽  
Field Trials ◽  
P Uptake ◽  
Fungal Colonization ◽  
P Availability ◽  
Terrestrial Plants ◽  
Soil Microbial ◽  
Arbuscular Mycorrhizal Fungal ◽  
P Supply

A vast majority of terrestrial plants are dependent on arbuscular mycorrhizal fungi (AMF) for their nutrient acquisition. AMF act as an extension of the root system helping phosphate uptake. In agriculture, harnessing the symbiosis can potentially increase plant growth. Application of the AMF Rhizophagus irregularis has been demonstrated to increase the yields of various crops. However, there is a paradigm that AMF colonization of roots, as well as the plant benefits afforded by inoculation with AMF, decreases with increasing phosphorus (P) supply in the soil. The paradigm suggests that when fertilized with sufficient P, inoculation of crops would not be beneficial. However, the majority of experiments demonstrating the paradigm were conducted in sterile conditions without a background AMF or soil microbial community. Interestingly, intraspecific variation in R. irregularis can greatly alter the yield of cassava even at a full application of the recommended P dose. Cassava is a globally important crop, feeding 800 million people worldwide, and a crop that is highly dependent on AMF for P uptake. In this study, field trials were conducted at three locations in Kenya and Tanzania using different AMF and cassava varieties under different P fertilization levels to test if the paradigm occurs in tropical field conditions. We found that AMF colonization and inoculation responsiveness of cassava does not always decrease with an increased P supply as expected by the paradigm. The obtained results demonstrate that maximizing the inoculation responsiveness of cassava is not necessarily only in conditions of low P availability, but that this is dependent on cassava and fungal genotypes. Thus, the modeling of plant symbiosis with AMF under different P levels in nature should be considered with caution.

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