Plant herbivore protection by arbuscular mycorrhizas: A role for fungal diversity?

The symbiotic association between arbuscular mycorrhizal (AM) fungi and terrestrial plants can enhance plant defences against insect herbivores. Despite advances in our understanding of how AM fungi affect plant tolerance and resistance based defence mechanisms, we contend that the role of fungal diversity in these interactions continues to be largely overlooked. This is problematic considering plants typically associate with multiple AM fungi in both natural and agriculturally managed environments in a way which varies spatially and temporally. While the importance of mycorrhizal fungal diversity is being increasingly incorporated into research efforts across various facets of ecology, progress on how AM fungal diversity mediates plant protection from herbivory is disparate and piecemeal. Here we discuss why it is important to focus efforts on understanding how AM fungal diversity can shape plant defence outcomes and highlight key knowledge gaps to be addressed.

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Cellular and molecular approaches in the characterization of symbiotic events in functional arbuscular mycorrhizal associations

Canadian Journal of Botany ◽

10.1139/b95-292 ◽

1995 ◽

Vol 73 (S1) ◽

pp. 526-532 ◽

Cited By ~ 45

Author(s):

Vivienne Gianinazzi-Pearson ◽

Armelle Gollotte ◽

Benoit Tisserant ◽

Philipp Franken ◽

Eliane Dumas-Gaudot ◽

...

Keyword(s):

Arbuscular Mycorrhizal Fungi ◽

Arbuscular Mycorrhiza ◽

Mycorrhizal Fungi ◽

Molecular Mechanisms ◽

Plant Defence ◽

Arbuscular Mycorrhizal ◽

Arbuscular Mycorrhizas ◽

Cellular Interactions ◽

Terrestrial Plants ◽

Molecular Approaches

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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It matters who you know, down below: Different mycorrhizal fungal communities differentially affect plant phenolic defences against herbivory

10.1101/2020.07.06.190710 ◽

2020 ◽

Author(s):

Adam Frew ◽

Bree A. L. Wilson

Keyword(s):

Fungal Community ◽

Community Assembly ◽

Plant Defence ◽

Insect Herbivory ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

Fungal Species ◽

Fungal Communities ◽

Insect Herbivore ◽

Terrestrial Plants

ABSTRACTArbuscular mycorrhizal (AM) fungi are ubiquitous symbionts of most terrestrial plants. These fungi not only provide their host plants with access to nutrients and resources but are known to augment plant defences against insect herbivores. Relatively little is known about the role of AM fungal diversity and community assembly on the expression of plant defence traits. Here, we report how plant (Triticum aestivum) phenolic-based resistance to insect herbivory is differentially affected by different AM fungal communities. An inoculant of four AM fungal species and a field-sourced native AM fungal community increased plant phenolics by 47.9% and 50.2%, respectively, compared to plants inoculated with only one fungal species. Correspondingly, the performance (relative growth rate) of the insect herbivore was 36% and 61.3% lower when feeding on plants associated with these AM fungal communities. Furthermore, there was a negative correlation between foliar phenolics and herbivore growth. We propose that AM fungal community assembly can drive insect herbivore performance by affecting phenolic-based defence mechanisms.

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Ectomycorrhizas accelerate decomposition to a greater extent than arbuscular mycorrhizas in a northern deciduous forest

10.1101/2021.02.09.430490 ◽

2021 ◽

Author(s):

Alexis Carteron ◽

Fabien Cichonski ◽

Etienne Laliberté

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Deciduous Forest ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

Arbuscular Mycorrhizas ◽

Fungal Hyphae ◽

Organic Horizons ◽

Temperate Deciduous ◽

Temperate Deciduous Forests

AbstractIt has been proposed that ectomycorrhizal (EcM) fungi slow down decomposition by competing with free-living saprotrophs for organic nutrients and other soil resources (known as the “Gadgil effect”), thereby increasing soil carbon sequestration. As such, this Gadgil effect should depend on soil organic matter age and quality, but this remains unstudied. In addition, the Gadgil effect is not expected to occur in arbuscular mycorrhizal (AM) forests since AM fungi cannot access directly nutrients from soil organic matter, yet few direct comparisons between EcM and AM forests have been made. We performed a two-year reciprocal decomposition experiment of soil organic horizons (litter - L, fragmented - F, humic - H) in adjacent temperate deciduous forests dominated by EcM or AM trees. Litterbags were made of different mesh sizes allowing or excluding ingrowth of external fungal hyphae, which are primarily mycorrhizal in these forests other than for the most-recent superficial litter horizon. As expected, organic matter originating from deeper horizons and from EcM forests was of lower quality (e.g. higher lignin to nitrogen ratios) and decomposed more slowly. However, contrary to the Gadgil effect, organic matter exposed to external fungal hyphae (i.e. primarily mycorrhizal) actually decomposed faster in both forest types, and this effect was strongest in EcM forests, particularly in the F horizon. Unexpectedly, organic matter decomposition was faster in EcM than in AM forests, regardless of organic matter origin. Overall, our study reinforces the view that temperate EcM forests store greater amounts of soil organic carbon than AM forests, but suggests that this is due to factors other than the Gadgil effect.

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Arbuscular Mycorrhizal Symbiosis Affects Plant Immunity to Viral Infection and Accumulation

Viruses ◽

10.3390/v11060534 ◽

2019 ◽

Vol 11 (6) ◽

pp. 534 ◽

Cited By ~ 8

Author(s):

Zhipeng Hao ◽

Wei Xie ◽

Baodong Chen

Keyword(s):

Viral Infection ◽

Plant Immunity ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

Plant Viruses ◽

Limiting Factors ◽

Systemic Resistance ◽

Mycorrhizal Symbiosis ◽

Complex Nature ◽

Terrestrial Plants

Arbuscular mycorrhizal (AM) fungi, as root symbionts of most terrestrial plants, improve plant growth and fitness. In addition to the improved plant nutritional status, the physiological changes that trigger metabolic changes in the root via AM fungi can also increase the host ability to overcome biotic and abiotic stresses. Plant viruses are one of the important limiting factors for the commercial cultivation of various crops. The effect of AM fungi on viral infection is variable, and considerable attention is focused on shoot virus infection. This review provides an overview of the potential of AM fungi as bioprotection agents against viral diseases and emphasizes the complex nature of plant–fungus–virus interactions. Several mechanisms, including modulated plant tolerance, manipulation of induced systemic resistance (ISR), and altered vector pressure are involved in such interactions. We propose that using “omics” tools will provide detailed insights into the complex mechanisms underlying mycorrhizal-mediated plant immunity.

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A review of the interaction of medicinal plants and arbuscular mycorrhizal fungi in the rhizosphere

Notulae Botanicae Horti Agrobotanici Cluj-Napoca ◽

10.15835/nbha49312454 ◽

2021 ◽

Vol 49 (3) ◽

pp. 12454

Author(s):

Rui-Ting SUN ◽

Ze-Zhi ZHANG ◽

Nong ZHOU ◽

A.K. SRIVASTAVA ◽

Kamil KUČA ◽

...

Keyword(s):

Medicinal Plants ◽

Mycorrhizal Fungi ◽

Growth Promotion ◽

Clinical Importance ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

Arbuscular Mycorrhizas ◽

High Concentration ◽

Clinical Drugs

Medicinal plants are well known to have the advantages of high concentration of medicinal ingredients having clinical importance, curative value, small toxic and side effects. Important compounds viz., paclitaxel, camptothecin, and vincristine have been developed from medicinal plants as first-line of clinical drugs, leading to their consistently increasing demand globally. However, the destruction of natural environment due to excessive mining threatened such resources jeopardizing the successful growing of medicinal plants. A group of beneficial arbuscular mycorrhizal (AM) fungi is known to exist in the rhizosphere of medicinal plants, which can establish a reciprocal symbiosis with their roots, namely arbuscular mycorrhizas. These AM fungi are pivotal in the habitat adaptation of medicinal plants. Studies have demonstrated that AM fungi aided in growth promotion and nutrient absorption of medicinal plants, thereby, accelerating the accumulation of medicinal ingredients and aiding resistance against abiotic stresses such as drought, low temperature, and salinity. An AM-like fungus Piriformospora indica is known to be cultured in vitro without roots, later showed analogous effects of AM fungi on medicinal plants. These fungi provide new mechanistic pathways towards the artificial cultivation of medicinal plants loaded with ingredients in huge demand in international market. This review provides an overview of the diversity of AM fungi inhabiting the rhizosphere of medicinal plants, and analyzes the functioning of AM fungi and P. indica, coupled with future lines of research.

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Trait-based aerial dispersal of arbuscular mycorrhizal fungi

10.1101/2020.02.12.943878 ◽

2020 ◽

Author(s):

V. Bala Chaudhary ◽

Sarah Nolimal ◽

Moisés A. Sosa-Hernández ◽

Cameron Egan ◽

Jude Kastens

Keyword(s):

Community Structure ◽

Mycorrhizal Fungi ◽

High Throughput Sequencing ◽

Fungal Spores ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

Global Scale ◽

Arbuscular Mycorrhizas ◽

List Type ◽

Aerial Dispersal

SUMMARYDispersal is a key process driving local-scale community assembly and global-scale biogeography of plant symbiotic arbuscular mycorrhizal (AM) fungal communities. A trait-based approach could improve predictions regarding how AM fungal aerial dispersal varies by species.We conducted month-long collections of aerial AM fungi for 12 consecutive months in an urban mesic environment at heights of 20 m. We measured functional traits of all collected spores and assessed aerial AM fungal community structure both morphologically and with high-throughput sequencing.Large numbers of AM fungal spores were present in the air over the course of one year and these spores were more likely to exhibit traits that facilitate dispersal. Aerial spores were smaller than average for Glomeromycotinan fungi. Trait-based predictions indicate that nearly 1/3 of described species from diverse genera demonstrate the potential for aerial dispersal. Diversity of aerial AM fungi was relatively high (20 spore species and 17 virtual taxa) and both spore abundance and community structure shifted temporally.The prevalence of aerial dispersal in arbuscular mycorrhizas is perhaps greater than previously indicated and a hypothesized model of AM fungal dispersal mechanisms is presented. Anthropogenic soil impacts may initiate the dispersal of disturbance-tolerating AM fungal species and facilitate community homogenization.

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Mycorrhizal Fungi and Sustainable Agriculture

10.5772/intechopen.99262 ◽

2021 ◽

Author(s):

Soibam Helena Devi ◽

Ingudam Bhupenchandra ◽

Soibam Sinyorita ◽

S.K. Chongtham ◽

E. Lamalakshmi Devi

Keyword(s):

Arbuscular Mycorrhizal Fungi ◽

Mycorrhizal Fungi ◽

Farming Systems ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

High Rate ◽

Natural Ecosystem ◽

Terrestrial Plants ◽

Nitrogen And Phosphorus ◽

Nutrient Assimilation

The 20thcentury witnessed an augmentation in agricultural production, mainly through the progress and use of pesticides, fertilizers containing nitrogen and phosphorus, and developments in plant breeding and genetic skills. In the naturally existing ecology, rhizospheric soils have innumerable biological living beings to favor the plant development, nutrient assimilation, stress tolerance, disease deterrence, carbon seizing and others. These organisms include mycorrhizal fungi, bacteria, actinomycetes, etc. which solubilize nutrients and assist the plants in up taking by roots. Amongst them, arbuscular mycorrhizal (AM) fungi have key importance in natural ecosystem, but high rate of chemical fertilizer in agricultural fields is diminishing its importance. The majority of the terrestrial plants form association with Vesicular Arbuscular Mycorrhiza (VAM) or Arbuscular Mycorrhizal fungi (AMF). This symbiosis confers benefits directly to the host plant’s growth and development through the acquisition of Phosphorus (P) and other mineral nutrients from the soil by the AMF. They may also enhance the protection of plants against pathogens and increases the plant diversity. This is achieved by the growth of AMF mycelium within the host root (intra radical) and out into the soil (extra radical) beyond. Proper management of Arbuscular Mycorrhizal fungi has the potential to improve the profitability and sustainability of agricultural systems. AM fungi are especially important for sustainable farming systems because AM fungi are efficient when nutrient availability is low and when nutrients are bound to organic matter and soil particles.

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Mycorrhizae Applications in Sustainable Forestry

10.5772/intechopen.94580 ◽

2020 ◽

Author(s):

Dayakar Govindu ◽

Anusha Duvva ◽

Srinivas Podeti

Keyword(s):

Plant Biomass ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

Sustainable Forestry ◽

Symbiotic Association ◽

Mycorrhizal Dependency ◽

Crop Varieties ◽

Am Symbiosis ◽

Wide Scale ◽

Forest Plants

Arbuscular mycorrhizal (AM) association is the most common symbiotic association of plants with microbes. AM fungi occur in the majority of natural habitats and they provide a range of important biological services, in particular by improving plant nutrition, abiotic resistance, and soil structure and fertility. AM fungi also interact with most crop varieties and forest plants. The possible benefit of AM fungi in forestry can be achieved through a combination of inoculum methods. The mycorrhizal inoculum levels in the soil and their colonization in different forest plant roots which leads to reduce the fertilizers, pathogen effects and fungicides and to protect topsoil, soil erosion, and water-logging. Currently, several reports were suggested that AM symbiosis can improve the potential for different plant species. Two steps could be used to produce high yielding of different plant biomass that would be both mycorrhizal dependency and suitability for sowing into the field with high inoculum levels Therefore, the wide-scale inoculation of AM fungi on forest trees will become economically important. The successful research is required in the area of mass production of AM fungal inoculum and AM fungi associated with roots which will contribute to sustainable forestry.

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Elucidating the Mechanisms Underlying Enhanced Drought Tolerance in Plants Mediated by Arbuscular Mycorrhizal Fungi

Frontiers in Microbiology ◽

10.3389/fmicb.2021.809473 ◽

2021 ◽

Vol 12 ◽

Author(s):

Shen Cheng ◽

Ying-Ning Zou ◽

Kamil Kuča ◽

Abeer Hashem ◽

Elsayed Fathi Abd_Allah ◽

...

Keyword(s):

Drought Stress ◽

Drought Tolerance ◽

Mycorrhizal Fungi ◽

Host Plants ◽

Molecular Mechanisms ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

Host Cells ◽

Future Research ◽

Symbiotic Association

Plants are often subjected to various environmental stresses during their life cycle, among which drought stress is perhaps the most significant abiotic stress limiting plant growth and development. Arbuscular mycorrhizal (AM) fungi, a group of beneficial soil fungi, can enhance the adaptability and tolerance of their host plants to drought stress after infecting plant roots and establishing a symbiotic association with their host plant. Therefore, AM fungi represent an eco-friendly strategy in sustainable agricultural systems. There is still a need, however, to better understand the complex mechanisms underlying AM fungi-mediated enhancement of plant drought tolerance to ensure their effective use. AM fungi establish well-developed, extraradical hyphae on root surfaces, and function in water absorption and the uptake and transfer of nutrients into host cells. Thus, they participate in the physiology of host plants through the function of specific genes encoded in their genome. AM fungi also modulate morphological adaptations and various physiological processes in host plants, that help to mitigate drought-induced injury and enhance drought tolerance. Several AM-specific host genes have been identified and reported to be responsible for conferring enhanced drought tolerance. This review provides an overview of the effect of drought stress on the diversity and activity of AM fungi, the symbiotic relationship that exists between AM fungi and host plants under drought stress conditions, elucidates the morphological, physiological, and molecular mechanisms underlying AM fungi-mediated enhanced drought tolerance in plants, and provides an outlook for future research.

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Arbuscular mycorrhizal fungi increase Pb uptake of colonized and non-colonized Medicago truncatula root and deliver extra Pb to colonized root

10.21203/rs.3.rs-208596/v1 ◽

2021 ◽

Author(s):

Haoqiang Zhang ◽

Wei Ren ◽

Yaru Zheng ◽

Fei Zhao ◽

Ming Tang

Keyword(s):

Medicago Truncatula ◽

Mycorrhizal Fungi ◽

Plant Root ◽

Biomass Accumulation ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

Shoot Biomass ◽

Terrestrial Plants ◽

Split Root ◽

Split Root System

Abstract Aims Arbuscular mycorrhizal (AM) fungi form symbiosis with terrestrial plants and improve lead (Pb) tolerance of host plants. The AM plants accumulate more Pb in root than their non-mycorrhizal counterparts. However, the direct contribution of the mycorrhizal pathway to host plant Pb uptake was less reported. Methods In this study, the AM fungi colonized and non-colonized root of Medicago truncatula was separated by a split-root system, and their differences in responding to Pb application was compared. Results Inoculation of Rhizophagus irregularis increased shoot biomass accumulation and transpiration, and decreased both colonized and non-colonized root biomass accumulation. Application of Pb in the non-colonized root compartment increased the colonization rate of R. irregularis and up-regulated the relative expressions of MtPT4 and MtBCP1 in the colonized root compartment. Inoculation of R. irregularis increased the Pb uptake in both colonized and non-colonized plant root, while R. irregularis transferred Pb to the colonized root. The Pb transferred through the mycorrhizal pathway had low mobility move from root to shoot, and might be sequestrated and compartmented by R. irregularis. Conclusions The Pb uptake of plant root might follow water flow that facilitated by the aquaporin MtPIP2. The quantification of Pb transfer via mycorrhizal pathway and the involvement of MtPIP2 deserve further study.

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