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1.
How mycorrhizal associations drive plant population and community biology.
Tedersoo, L, Bahram, M, Zobel, M
Science (New York, N.Y.). 2020;(6480)
Abstract
Mycorrhizal fungi provide plants with a range of benefits, including mineral nutrients and protection from stress and pathogens. Here we synthesize current information about how the presence and type of mycorrhizal association affect plant communities. We argue that mycorrhizal fungi regulate seedling establishment and species coexistence through stabilizing and equalizing mechanisms such as soil nutrient partitioning, feedback to soil antagonists, differential mycorrhizal benefits, and nutrient trade. Mycorrhizal fungi have strong effects on plant population and community biology, with mycorrhizal type-specific effects on seed dispersal, seedling establishment, and soil niche differentiation, as well as interspecific and intraspecific competition and hence plant diversity.
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2.
Significance of Arbuscular Mycorrhizal Fungi for Acacia: A Review.
Saini, I, Himanshi, , Rani, K, Gill, N, Sandhu, K, Bisht, N, Kumar, T, Kaushik, P
Pakistan journal of biological sciences : PJBS. 2020;(10):1231-1236
Abstract
Microbes play a vital role in ecosystem stability. Here, microbes-Acacia association is discussed with particular reference to Arbuscular Mycorrhizal Fungi (AMF) which help in the establishment of crop-plants, especially in arid and semi-arid areas. The association helps to restore the structural composition of soil from the hazardous impact of agrochemicals, increase resistance against various pathogenic attack as well as several abiotic stresses. Further, a comparative account of microbes found in the rhizosphere of Acacia is illustrated. Among these, Rhizobia, Acetobacter, Bradyrhizobium, Bacillus, Pseudomonas and Trichoderma were described in detail. All these microbes can be regarded as Plant Growth Promoting Rhizospheric Microbes (PGPM), some of PGPM are Phosphate Solubilizing Microbe (PSM). Both of them help AMF for infecting mycorrhizal hyphae inside the plant cell. Overall, microbes can be used as biofertilizers along with other organic compounds, that can compensate for the nutrient's availability.
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3.
The potential of arbuscular mycorrhizal fungi in C cycling: a review.
Parihar, M, Rakshit, A, Meena, VS, Gupta, VK, Rana, K, Choudhary, M, Tiwari, G, Mishra, PK, Pattanayak, A, Bisht, JK, et al
Archives of microbiology. 2020;(7):1581-1596
Abstract
Arbuscular mycorrhizal fungi (AMF) contribute predominantly to soil organic matter by creating a sink demand for plant C and distributing to below-ground hyphal biomass. The extra-radical hyphae along with glomalin-related soil protein significantly influence the soil carbon dynamics through their larger extent and turnover period need to discuss. The role of AMF is largely overlooked in terrestrial C cycling and climate change models despite their greater involvement in net primary productivity augmentation and further accumulation of this additional photosynthetic fixed C in the soil. However, this buffering mechanism against elevated CO2 condition to sequester extra C by AMF can be described only after considering their potential interaction with other microbes and associated mineral nutrients such as nitrogen cycling. In this article, we try to review the potential of AMF in C sequestration paving the way towards a better understanding of possible AMF mechanism by which C balance between biosphere and atmosphere can be moved forward in more positive direction.
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4.
Direct and indirect influence of arbuscular mycorrhizae on enhancing metal tolerance of plants.
Janeeshma, E, Puthur, JT
Archives of microbiology. 2020;(1):1-16
Abstract
The acerbic elevation of toxic metal ions in arable lands, enhance the risk of their accumulation and biomagnification in crops as well as in humans. Phytoremediation is an eco-friendly approach to clear metal-contaminated lands by making use of metal accumulation potential of plants; which are referred to as hyperaccumulators. This phytoremediation potential can be enhanced with the symbiotic association between the root of hyperaccumulators and arbuscular mycorrhizae. Modification of root morphology, enhancement of antioxidants biosynthesis, and the increase in shoot biomass are the changes observed in plants as a result of indirect influence of arbuscular mycorrhizae. Direct influence of arbuscular mycorrhizae on enhancing metal tolerance of plants includes immobilization strategies, adsorption of metals on to the hyphal wall and glomalin exudation. Furthermore, we have discussed arbuscular mycorrhizal induced increment in the metal tolerance potential of plants through the alteration in various metabolic processes with special emphasis to the phenylpropanoid pathway.
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5.
In Vivo Metabolic Regulation of Alternative Oxidase under Nutrient Deficiency-Interaction with Arbuscular Mycorrhizal Fungi and Rhizobium Bacteria.
Ortíz, J, Sanhueza, C, Romero-Munar, A, Hidalgo-Castellanos, J, Castro, C, Bascuñán-Godoy, L, Coba de la Peña, T, López-Gómez, M, Florez-Sarasa, I, Del-Saz, NF
International journal of molecular sciences. 2020;(12)
Abstract
The interaction of the alternative oxidase (AOX) pathway with nutrient metabolism is important for understanding how respiration modulates ATP synthesis and carbon economy in plants under nutrient deficiency. Although AOX activity reduces the energy yield of respiration, this enzymatic activity is upregulated under stress conditions to maintain the functioning of primary metabolism. The in vivo metabolic regulation of AOX activity by phosphorus (P) and nitrogen (N) and during plant symbioses with Arbuscular mycorrhizal fungi (AMF) and Rhizobium bacteria is still not fully understood. We highlight several findings and open questions concerning the in vivo regulation of AOX activity and its impact on plant metabolism during P deficiency and symbiosis with AMF. We also highlight the need for the identification of which metabolic regulatory factors of AOX activity are related to N availability and nitrogen-fixing legume-rhizobia symbiosis in order to improve our understanding of N assimilation and biological nitrogen fixation.
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6.
Productivity and quality of horticultural crops through co-inoculation of arbuscular mycorrhizal fungi and plant growth promoting bacteria.
Emmanuel, OC, Babalola, OO
Microbiological research. 2020;:126569
Abstract
Associations between plants and microorganisms exist in nature, and they can either be beneficial or detrimental to host plants. Promoting beneficial plant-microbe interaction for increased crop yield and quality is one pathway to eco-friendly and sustainable crop production. Arbuscular mycorrhizal fungi (AMF) and plant growth promoting bacteria (PGPB) are microorganisms that are beneficial to horticultural crops. Arbuscular mycorrhizal fungi establish symbioses with plant roots which help to improve nutrient uptake by the host plant and alter its physiology to withstand external abiotic factors and pathogens. Plant growth promoting bacteria promote plant growth either directly by aiding resource acquisition and controlling the levels of plant hormones or indirectly by reducing the inhibitory effects of phytopathogens. Co-inoculation of both organisms combines the benefits of each for increased crop productivity. Even though the co-inoculation of PGPB and AMF have been shown to enhance the yield and quality of crops, its benefits have fully not been exploited for horticultural crops. In this review, the response of horticultural crops to co-inoculation with PGPB and AMF with particular interest to the impact on the yield and crop quality was discussed. We explained some of the mechanisms responsible for the synergy between AMF and PGPB in plant growth promotion. Finally, suggestions on areas that need to be researched further to exploit and improve the effects of these organisms were highlighted.
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7.
Ectomycorrhizal symbiosis helps plants to challenge salt stress conditions.
Guerrero-Galán, C, Calvo-Polanco, M, Zimmermann, SD
Mycorrhiza. 2019;(4):291-301
Abstract
Soil salinity is an environmental condition that is currently increasing worldwide. Plant growth under salinity induces osmotic stress and ion toxicity impairing root water and nutrient absorption, but the association with beneficial soil microorganisms has been linked to an improved adaptation to this constraint. The ectomycorrhizal (ECM) symbiosis has been proposed as a key factor for a better tolerance of woody species to salt stress, thanks to the reduction of sodium (Na+) uptake towards photosynthetic organs. Although no precise mechanisms for this enhanced plant salt tolerance have been described yet, in this review, we summarize the knowledge accumulated so far on the role of ECM symbiosis. Moreover, we propose several strategies by which ECM fungi might help plants, including restriction of Na+ entrance into plant tissues and improvement of mineral nutrition and water balances. This positive effect of ECM fungi has been proven in field assays and the results obtained point to a promising application in forestry cultures and reforestation.
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8.
The role of nutrient balance in shaping plant root-fungal interactions: facts and speculation.
Fabiańska, I, Sosa-Lopez, E, Bucher, M
Current opinion in microbiology. 2019;:90-96
Abstract
Microbiota colonizing plant roots and their vicinity were shown not to be just random associations, but compose, at least to some extent, host-selected microbial consortia. The plant physiological status, especially the nutrient status, prompts changes in plant morphology and metabolism, which successively imposes a selective pressure on microbial communities. It is well established that a low phosphate status of the host plant activates the molecular machinery underlying the development of mutualistic associations in the host root with arbuscular mycorrhizal fungi (AMF). We hypothesize that the plant´s response to changing nutrient stoichiometry affects processes at the root-mycosphere interface which promote or repress also root interactions with microbial taxa other than AMF. As a consequence, fundamental mechanisms underlying these interactions would be shared in AM host and non-host plants. A detailed understanding of the processes involved in maintenance of plant nutrient homeostasis could contribute to novel strategies in tailoring predominantly parasitic or commensalistic plant-microbe interactions towards beneficial associations.
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9.
Exploring the role of ectomycorrhizal fungi in soil carbon dynamics.
Zak, DR, Pellitier, PT, Argiroff, W, Castillo, B, James, TY, Nave, LE, Averill, C, Beidler, KV, Bhatnagar, J, Blesh, J, et al
The New phytologist. 2019;(1):33-39
Abstract
The extent to which ectomycorrhizal (ECM) fungi enable plants to access organic nitrogen (N) bound in soil organic matter (SOM) and transfer this growth-limiting nutrient to their plant host, has important implications for our understanding of plant-fungal interactions, and the cycling and storage of carbon (C) and N in terrestrial ecosystems. Empirical evidence currently supports a range of perspectives, suggesting that ECM vary in their ability to provide their host with N bound in SOM, and that this capacity can both positively and negatively influence soil C storage. To help resolve the multiplicity of observations, we gathered a group of researchers to explore the role of ECM fungi in soil C dynamics, and propose new directions that hold promise to resolve competing hypotheses and contrasting observations. In this Viewpoint, we summarize these deliberations and identify areas of inquiry that hold promise for increasing our understanding of these fundamental and widespread plant symbionts and their role in ecosystem-level biogeochemistry.
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10.
Review: Arbuscular mycorrhizas as key players in sustainable plant phosphorus acquisition: An overview on the mechanisms involved.
Ferrol, N, Azcón-Aguilar, C, Pérez-Tienda, J
Plant science : an international journal of experimental plant biology. 2019;:441-447
Abstract
Phosphorus (P) is a poorly available macronutrient essential for plant growth and development and consequently for successful crop yield and ecosystem productivity. To cope with P limitations plants have evolved strategies for enhancing P uptake and/or improving P efficiency use. The universal 450-million-yr-old arbuscular mycorrhizal (AM) (fungus-root) symbioses are one of the most successful and widespread strategies to maximize access of plants to available P. AM fungi biotrophically colonize the root cortex of most plant species and develop an extraradical mycelium which overgrows the nutrient depletion zone of the soil surrounding plant roots. This hyphal network is specialized in the acquisition of low mobility nutrients from soil, particularly P. During the last years, molecular biology techniques coupled to novel physiological approaches have provided fascinating contributions to our understanding of the mechanisms of symbiotic P transport. Mycorrhiza-specific plant phosphate transporters, which are required not only for symbiotic P transfer but also for maintenance of the symbiosis, have been identified. The present review provides an overview of the contribution of AM fungi to plant P acquisition and an update of recent findings on the physiological, molecular and regulatory mechanisms of P transport in the AM symbiosis.