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Pitman EL, Counihan NA, Modak JK, Chowdury M, Gilson PR, Webb CT, de Koning-Ward TF. Dissecting EXP2 sequence requirements for protein export in malaria parasites. Front Cell Infect Microbiol 2024; 13:1332146. [PMID: 38282616 PMCID: PMC10811066 DOI: 10.3389/fcimb.2023.1332146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 12/19/2023] [Indexed: 01/30/2024] Open
Abstract
Apicomplexan parasites that reside within a parasitophorous vacuole harbor a conserved pore-forming protein that enables small-molecule transfer across the parasitophorous vacuole membrane (PVM). In Plasmodium parasites that cause malaria, this nutrient pore is formed by EXP2 which can complement the function of GRA17, an orthologous protein in Toxoplasma gondii. EXP2, however, has an additional function in Plasmodium parasites, serving also as the pore-forming component of the protein export machinery PTEX. To examine how EXP2 can play this additional role, transgenes that encoded truncations of EXP2, GRA17, hybrid GRA17-EXP2, or EXP2 under the transcriptional control of different promoters were expressed in EXP2 knockdown parasites to determine which could complement EXP2 function. This revealed that EXP2 is a unique pore-forming protein, and its protein export role in P. falciparum cannot be complemented by T. gondii GRA17. This was despite the addition of the EXP2 assembly strand and part of the linker helix to GRA17, which are regions necessary for the interaction of EXP2 with the other core PTEX components. This indicates that the body region of EXP2 plays a critical role in PTEX assembly and/or that the absence of other T. gondii GRA proteins in P. falciparum leads to its reduced efficiency of insertion into the PVM and complementation potential. Altering the timing and abundance of EXP2 expression did not affect protein export but affected parasite viability, indicating that the unique transcriptional profile of EXP2 when compared to other PTEX components enables it to serve an additional role in nutrient exchange.
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Affiliation(s)
- Ethan L. Pitman
- School of Medicine, Deakin University, Geelong, VIC, Australia
- Institute for Mental and Physical Health and Clinical Translation (IMPACT), Deakin University, Geelong, VIC, Australia
| | - Natalie A. Counihan
- School of Medicine, Deakin University, Geelong, VIC, Australia
- Institute for Mental and Physical Health and Clinical Translation (IMPACT), Deakin University, Geelong, VIC, Australia
| | - Joyanta K. Modak
- School of Medicine, Deakin University, Geelong, VIC, Australia
- Institute for Mental and Physical Health and Clinical Translation (IMPACT), Deakin University, Geelong, VIC, Australia
| | - Mrittika Chowdury
- School of Medicine, Deakin University, Geelong, VIC, Australia
- Institute for Mental and Physical Health and Clinical Translation (IMPACT), Deakin University, Geelong, VIC, Australia
| | - Paul R. Gilson
- Burnet Institute, Melbourne, VIC, Australia
- Department of Microbiology and Immunology, University of Melbourne, Parkville, VIC, Australia
| | - Chaille T. Webb
- Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC, Australia
- Centre to Impact AMR, Monash University, Clayton, VIC, Australia
| | - Tania F. de Koning-Ward
- School of Medicine, Deakin University, Geelong, VIC, Australia
- Institute for Mental and Physical Health and Clinical Translation (IMPACT), Deakin University, Geelong, VIC, Australia
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Jacobovitz MR, Hambleton EA, Guse A. Unlocking the Complex Cell Biology of Coral-Dinoflagellate Symbiosis: A Model Systems Approach. Annu Rev Genet 2023; 57:411-434. [PMID: 37722685 DOI: 10.1146/annurev-genet-072320-125436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/20/2023]
Abstract
Symbiotic interactions occur in all domains of life, providing organisms with resources to adapt to new habitats. A prime example is the endosymbiosis between corals and photosynthetic dinoflagellates. Eukaryotic dinoflagellate symbionts reside inside coral cells and transfer essential nutrients to their hosts, driving the productivity of the most biodiverse marine ecosystem. Recent advances in molecular and genomic characterization have revealed symbiosis-specific genes and mechanisms shared among symbiotic cnidarians. In this review, we focus on the cellular and molecular processes that underpin the interaction between symbiont and host. We discuss symbiont acquisition via phagocytosis, modulation of host innate immunity, symbiont integration into host cell metabolism, and nutrient exchange as a fundamental aspect of stable symbiotic associations. We emphasize the importance of using model systems to dissect the cellular complexity of endosymbiosis, which ultimately serves as the basis for understanding its ecology and capacity to adapt in the face of climate change.
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Affiliation(s)
- Marie R Jacobovitz
- Cell Biology and Biophysics, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Elizabeth A Hambleton
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria;
| | - Annika Guse
- Faculty of Biology, Ludwig-Maximilians-Universität Munich, Munich, Germany;
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3
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Montesinos-Navarro A. Nitrogen transfer between plant species with different temporal N-demand. Ecol Lett 2023; 26:1676-1686. [PMID: 37340907 DOI: 10.1111/ele.14279] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 05/25/2023] [Accepted: 05/31/2023] [Indexed: 06/22/2023]
Abstract
Phenological segregation among species in a community is assumed to promote coexistence, as using resources at different times reduces competition. However, other unexplored nonalternative mechanisms can also result in a similar outcome. This study first tests whether plants can redistribute nitrogen (N) among them based on their nutritional temporal demand (i.e. phenology). Field 15 N labelling experiments showed that 15 N is transferred between neighbour plants, mainly from low N-demand (late flowering species, not reproducing yet) to high N-demand plants (early flowering species, currently flowering-fruiting). This can reduce species' dependence on pulses of water availability, and avoid soil N loss through leaching, having relevant implications in the structuring of plant communities and ecosystem functioning. Considering that species phenological segregation is a pervasive pattern in plant communities, this can be a so far unnoticed, but widely spread, ecological process that can predict N fluxes among species in natural communities, and therefore impact our current understanding of community ecology and ecosystem functioning.
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Affiliation(s)
- A Montesinos-Navarro
- Centro de Investigaciones Sobre Desertificación (CIDE, CSIC-UV-GV), Moncada, Spain
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4
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Lobel GP, Jiang Y, Simon MC. Tumor microenvironmental nutrients, cellular responses, and cancer. Cell Chem Biol 2023; 30:1015-1032. [PMID: 37703882 PMCID: PMC10528750 DOI: 10.1016/j.chembiol.2023.08.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 08/17/2023] [Accepted: 08/22/2023] [Indexed: 09/15/2023]
Abstract
Over the last two decades, the rapidly expanding field of tumor metabolism has enhanced our knowledge of the impact of nutrient availability on metabolic reprogramming in cancer. Apart from established roles in cancer cells themselves, various nutrients, metabolic enzymes, and stress responses are key to the activities of tumor microenvironmental immune, fibroblastic, endothelial, and other cell types that support malignant transformation. In this article, we review our current understanding of how nutrient availability affects metabolic pathways and responses in both cancer and "stromal" cells, by dissecting major examples and their regulation of cellular activity. Understanding the relationship of nutrient availability to cellular behaviors in the tumor ecosystem will broaden the horizon of exploiting novel therapeutic vulnerabilities in cancer.
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Affiliation(s)
- Graham P Lobel
- Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Yanqing Jiang
- Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - M Celeste Simon
- Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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5
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Durant E, Hoysted GA, Howard N, Sait SM, Childs DZ, Johnson D, Field KJ. Herbivore-driven disruption of arbuscular mycorrhizal carbon-for- nutrient exchange is ameliorated by neighboring plants. Curr Biol 2023:S0960-9822(23)00663-2. [PMID: 37290441 DOI: 10.1016/j.cub.2023.05.033] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 04/20/2023] [Accepted: 05/15/2023] [Indexed: 06/10/2023]
Abstract
Arbuscular mycorrhizal fungi colonize the roots of most plants, forming a near-ubiquitous symbiosis1 that is typically characterized by the bi-directional exchange of fungal-acquired nutrients for plant-fixed carbon.2 Mycorrhizal fungi can form below-ground networks3,4,5,6 with potential to facilitate the movement of carbon, nutrients, and defense signals across plant communities.7,8,9 The importance of neighbors in mediating carbon-for-nutrient exchange between mycorrhizal fungi and their plant hosts remains equivocal, particularly when other competing pressures for plant resources are present. We manipulated carbon source and sink strengths of neighboring pairs of host plants through exposure to aphids and tracked the movement of carbon and nutrients through mycorrhizal fungal networks with isotope tracers. When carbon sink strengths of both neighboring plants were increased by aphid herbivory, plant carbon supply to extraradical mycorrhizal fungal hyphae was reduced, but mycorrhizal phosphorus supply to both plants was maintained, albeit variably, across treatments. However, when the sink strength of only one plant in a pair was increased, carbon supply to mycorrhizal fungi was restored. Our results show that loss of carbon inputs into mycorrhizal fungal hyphae from one plant may be ameliorated through inputs of a neighbor, demonstrating the responsiveness and resilience of mycorrhizal plant communities to biological stressors. Furthermore, our results indicate that mycorrhizal nutrient exchange dynamics are better understood as community-wide interactions between multiple players rather than as strict exchanges between individual plants and their symbionts, suggesting that mycorrhizal C-for-nutrient exchange is likely based more on unequal terms of trade than the "fair trade" model for symbiosis.
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Affiliation(s)
- Emily Durant
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, South Yorkshire S10 2TN, UK
| | - Grace A Hoysted
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, South Yorkshire S10 2TN, UK; School of Biology and Environmental Science, University College Dublin, Dublin, County Dublin D4, Ireland
| | - Nathan Howard
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, South Yorkshire S10 2TN, UK
| | - Steven M Sait
- School of Biology, University of Leeds, Leeds, West Yorkshire LS2 9JT, UK
| | - Dylan Z Childs
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, South Yorkshire S10 2TN, UK
| | - David Johnson
- Department of Earth and Environmental Sciences, University of Manchester, Manchester, Greater Manchester M13 9PT, UK
| | - Katie J Field
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, South Yorkshire S10 2TN, UK.
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6
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Abstract
Plant roots associate with diverse microbes (including bacteria, fungi, archaea, protists, and viruses) collectively called the root-associated microbiome. Among them, mycorrhizal fungi colonize host roots and improve their access to nutrients, usually phosphorus and nitrogen. In exchange, plants deliver photosynthetic carbon to the colonizing fungi. This nutrient exchange affects key soil processes, the carbon cycle, and plant health and therefore has a strong influence on the plant and microbe ecosystems. The framework of nutrient exchange and regulation between host plant and arbuscular mycorrhizal fungi has recently been established. The local and systemic regulation of mycorrhizal symbiosis by plant nutrient status and the autoregulation of mycorrhizae are strategies by which plants maintain a stabilizing free-market symbiosis. A better understanding of the synergistic effects between mycorrhizal fungi and mycorrhizosphere microorganisms is an essential precondition for their use as biofertilizers and bioprotectors for sustainable agriculture and forestry management.
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Affiliation(s)
- Jincai Shi
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China;
| | - Xiaolin Wang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China;
| | - Ertao Wang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China;
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Scartazza A, Sbrana C, D'Andrea E, Matteucci G, Rezaie N, Lauteri M. Above- and belowground interplay: Canopy CO 2 uptake, carbon and nitrogen allocation and isotope fractionation along the plant-ectomycorrhiza continuum. Plant Cell Environ 2023; 46:889-900. [PMID: 36541420 DOI: 10.1111/pce.14519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 12/02/2022] [Accepted: 12/17/2022] [Indexed: 06/17/2023]
Abstract
In forests, mycorrhizal fungi regulate carbon (C) and nitrogen (N) dynamics. We evaluated the interplay among ectomycorrhizas (ECM), ecosystem C fluxes, tree productivity, C and N exchange and isotopic fractionation along the soil-ECM-plant continuum in a Mediterranean beech forest. From bud break to leaf shedding, we monitored: net ecosystem exchange (NEE, a measure of the net exchange of C between an ecosystem and the atmosphere), leaf area index, stem growth, N concentration, δ13 C and δ15 N in rhizosphere soil, ectomycorrhizal fine root tips (ERT), ECM-free fine root portions (NCR) and leaves. Seasonal changes in ERT relative biomass were strictly related to NEE and mimicked those detected in the radial growth. The analysis of δ13 C in ERT, leaves and NCR highlighted the impact of canopy photosynthesis on ERT development and an asynchronous seasonal C allocation strategy between ERT and NCR at the root tips level. Concerning N, δ15 N of leaves was negatively related to that of ERT and dependent on seasonal 15 N differences between ERT and NCR. Our results unravel a synchronous C allocation towards ERT and tree stem driven by the increasing NEE in spring-early summer. Moreover, they highlighted a phenology-dependent 15 N fractionation during N transfer from ECM to their hosts. This evidence, obtained in mature beech trees under natural conditions, may improve the knowledge of Mediterranean forests functionality.
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Affiliation(s)
- Andrea Scartazza
- Research Institute on Terrestrial Ecosystems, National Research Council of Italy (CNR-IRET), Pisa, Italy
- National Biodiversity Future Center (NBFC), Palermo, Italy
| | - Cristiana Sbrana
- Institute of Agricultural Biology and Biotechnology, National Research Council of Italy (CNR-IBBA), Pisa, Italy
| | - Ettore D'Andrea
- National Biodiversity Future Center (NBFC), Palermo, Italy
- Research Institute on Terrestrial Ecosystems, National Research Council of Italy (CNR-IRET), Porano, Italy
| | - Giorgio Matteucci
- National Biodiversity Future Center (NBFC), Palermo, Italy
- Institute for BioEconomy, National Research Council of Italy (CNR-IBE), Sesto Fiorentino, Italy
| | - Negar Rezaie
- Research Institute on Terrestrial Ecosystems, National Research Council of Italy (CNR-IRET), Napoli, Italy
| | - Marco Lauteri
- Research Institute on Terrestrial Ecosystems, National Research Council of Italy (CNR-IRET), Porano, Italy
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Gao M, Armin G, Inomura K. Low-Ammonium Environment Increases the Nutrient Exchange between Diatom-Diazotroph Association Cells and Facilitates Photosynthesis and N 2 Fixation-a Mechanistic Modeling Analysis. Cells 2022; 11:cells11182911. [PMID: 36139486 PMCID: PMC9497195 DOI: 10.3390/cells11182911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/09/2022] [Accepted: 09/13/2022] [Indexed: 11/16/2022] Open
Abstract
Diatom–diazotroph associations (DDAs) are one of the most important symbiotic dinitrogen (N2) fixing groups in the oligotrophic ocean. Despite their capability to fix N2, ammonium (NH4+) remains a key nitrogen (N) source for DDAs, and the effect of NH4+ on their metabolism remains elusive. Here, we developed a coarse-grained, cellular model of the DDA with NH4+ uptake and quantified how the level of extracellular NH4+ influences metabolism and nutrient exchange within the symbiosis. The model shows that, under a fixed growth rate, an increased NH4+ concentration may lower the required level of N2 fixation and photosynthesis, and decrease carbon (C) and N exchange. A low-NH4+ environment leads to more C and N in nutrient exchange and more fixed N2 to support a higher growth rate. With higher growth rates, nutrient exchange and metabolism increased. Our study shows a strong effect of NH4+ on metabolic processes within DDAs, and thus highlights the importance of in situ measurement of NH4+ concentrations.
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Affiliation(s)
- Meng Gao
- Correspondence: ; Tel.: +1-401-771-5757
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9
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Almario J, Fabiańska I, Saridis G, Bucher M. Unearthing the plant-microbe quid pro quo in root associations with beneficial fungi. New Phytol 2022; 234:1967-1976. [PMID: 35239199 DOI: 10.1111/nph.18061] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 02/09/2022] [Indexed: 06/14/2023]
Abstract
Mutualistic symbiotic associations between multicellular eukaryotes and their microbiota are driven by the exchange of nutrients in a quid pro quo manner. In the widespread arbuscular mycorrhizal (AM) symbiosis involving plant roots and Glomeromycotina fungi, the mycobiont is supplied with carbon through photosynthesis, which in return supplies the host plant with essential minerals such as phosphorus (P). Most terrestrial plants are largely dependent on AM fungi for nutrients, which raises the question of how plants that are unable to form a functional AM sustain their P nutrition. AM nonhost plants can form alternative, evolutionarily younger, mycorrhizal associations such as the ectomycorrhiza, ericoid and orchid mycorrhiza. However, it is unclear how plants such as the Brassicaceae species Arabidopsis thaliana, which do not form known mycorrhizal symbioses, have adapted to the loss of these essential mycorrhizal traits. Isotope tracing experiments with root-colonizing fungi have revealed the existence of new 'mycorrhizal-like' fungi capable of transferring nutrients such as nitrogen (N) and P to plants, including Brassicaceae. Here, we provide an overview of the biology of trophic relationships between roots and fungi and how these associations might support plant adaptation to climate change.
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Affiliation(s)
- Juliana Almario
- Ecologie Microbienne, CNRS UMR-5557, INRAe UMR-1418, VetAgroSup, Université de Lyon, Université Claude Bernard Lyon1, 43 Boulevard du 11 novembre 1918, Villeurbanne, 69622, France
| | - Izabela Fabiańska
- Institute for Plant Sciences, Cologne Biocenter, University of Cologne, Cologne, 50674, Germany
| | - Georgios Saridis
- Institute for Plant Sciences, Cologne Biocenter, University of Cologne, Cologne, 50674, Germany
| | - Marcel Bucher
- Institute for Plant Sciences, Cologne Biocenter, University of Cologne, Cologne, 50674, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, Cologne, 50931, Germany
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10
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Sathe RRM, Paerl RW, Hazra AB. Exchange of Vitamin B 1 and Its Biosynthesis Intermediates Shapes the Composition of Synthetic Microbial Cocultures and Reveals Complexities of Nutrient Sharing. J Bacteriol 2022;:e0050321. [PMID: 35357164 DOI: 10.1128/jb.00503-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Microbial communities occupy diverse niches in nature, and community members routinely exchange a variety of nutrients among themselves. While large-scale metagenomic and metabolomic studies shed some light on these exchanges, the contribution of individual species and the molecular details of specific interactions are difficult to track. In this study, we follow the exchange of vitamin B1 (thiamin) and its intermediates between microbes within synthetic cocultures of Escherichia coli and Vibrio anguillarum. Thiamin contains two moieties, 4-amino-5-hydroxymethyl-2-methylpyrimidine (HMP) and 4-methyl-5-(2-hydroxyethyl)thiazole (THZ), which are synthesized by distinct pathways using enzymes ThiC and ThiG, respectively, and then coupled by ThiE to form thiamin. Even though E. coli ΔthiC, ΔthiE, and ΔthiG mutants are thiamin auxotrophs, we observed that cocultures of ΔthiC-ΔthiE and ΔthiC-ΔthiG mutants are able to grow in a thiamin-deficient medium, whereas the ΔthiE-ΔthiG coculture does not. Further, the exchange of thiamin and its intermediates in V. anguillarum cocultures and in mixed cocultures of V. anguillarum and E. coli revealed that there exist specific patterns for thiamin metabolism and exchange among these microbes. Our findings show that HMP is shared more frequently than THZ, concurrent with previous observations that free HMP and HMP auxotrophy is commonly found in various environments. Furthermore, we observe that the availability of exogenous thiamin in the media affects whether these strains interact with each other or grow independently. These findings collectively underscore the importance of the exchange of essential metabolites as a defining factor in building and modulating synthetic or natural microbial communities. IMPORTANCE Vitamin B1 (thiamin) is an essential nutrient for cellular metabolism. Microorganisms that are unable to synthesize thiamin either fully or in part exogenously obtain it from their environment or via exchanges with other microbial members in their community. In this study, we created synthetic microbial cocultures that rely on sharing thiamin and its biosynthesis intermediates and observed that some of them are preferentially exchanged. We also observed that the coculture composition is dictated by the production and/or availability of thiamin and its intermediates. Our studies with synthetic cocultures provide the molecular basis for understanding thiamin sharing among microorganisms and lay out broad guidelines for setting up synthetic microbial cocultures by using the exchange of an essential metabolite as their foundation.
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Martignoni MM, Garnier J, Zhang X, Rosa D, Kokkoris V, Tyson RC, Hart MM. Co-inoculation with arbuscular mycorrhizal fungi differing in carbon sink strength induces a synergistic effect in plant growth. J Theor Biol 2021; 531:110859. [PMID: 34389360 DOI: 10.1016/j.jtbi.2021.110859] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 07/28/2021] [Accepted: 08/03/2021] [Indexed: 11/24/2022]
Abstract
Arbuscular mycorrhizal (AM) fungi play a key role in determining ecosystem functionality. Understanding how diversity in the fungal community affects plant productivity is therefore an important question in ecology. Current research has focused on understanding the role of functional complementarity in the fungal community when the host plant faces multiple stress factors. Fewer studies, however, have investigated how variation in traits affecting nutrient exchange can impact the plant growth dynamics, even in the absence of environmental stressors. Combining experimental data and a mathematical model based on ordinary differential equations, we investigate the role played by carbon sink strength on plant productivity. We simulate and measure plant growth over time when the plant is associated with two fungal isolates with different carbon sink strength, and when the plant is in pairwise association with each of the isolates alone. Overall, our theoretical as well as our experimental results show that co-inoculation with fungi with different carbon sink strength can induce positive non-additive effects (or synergistic effects) in plant productivity. Fungi with high carbon sink strength are able to quickly establish a fungal community and increase the nutrient supply to the plant, with a consequent positive impact on plant growth rate. On the other side, fungi with low carbon sink strength inflict lower carbon costs to the host plant, and support maximal plant productivity once plant biomass is large. As AM fungi are widely used as organic fertilizers worldwide, our findings have important implications for restoration ecology and agricultural management.
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Affiliation(s)
- Maria M Martignoni
- Department of Mathematics, University of British Columbia, Kelowna (BC), Canada; Department of Mathematics and Statistics, Memorial University, St. John's (NL), Canada
| | - Jimmy Garnier
- LAboratoire de MAthématiques (LAMA), CNRS, Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, Chambery, France
| | - Xinlu Zhang
- Department of Biology, University of British Columbia, Kelowna (BC), Canada
| | - Daniel Rosa
- Department of Biology, University of British Columbia, Kelowna (BC), Canada
| | - Vasilis Kokkoris
- Department of Biology, University of Ottawa, Ottawa (ON), Canada; Agriculture and Agri-Food Canada, Ottawa Research and Development Centre, Ottawa (ON), Canada
| | - Rebecca C Tyson
- Department of Mathematics, University of British Columbia, Kelowna (BC), Canada
| | - Miranda M Hart
- Department of Biology, University of British Columbia, Kelowna (BC), Canada
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12
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Chen X, Yang Z, Chen H, Qi Q, Liu J, Wang C, Shao S, Lu Q, Li Y, Wu H, King-Jones K, Chen MS. A Complex Nutrient Exchange Between a Gall-Forming Aphid and Its Plant Host. Front Plant Sci 2020; 11:811. [PMID: 32733495 PMCID: PMC7358401 DOI: 10.3389/fpls.2020.00811] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 05/19/2020] [Indexed: 06/11/2023]
Abstract
It has been a long-standing question as to whether the interaction between gall-forming insects and their host plants is merely parasitic or whether it may also benefit the host. On its host Rhus chinensis, the aphid Schlechtendalia chinensis induces the formation of closed galls, referred to as horned galls. Typically, mature aphid populations comprise thousands of individuals, which is sufficient to cause the accumulation of high CO2 levels in galls (on average 8-fold higher and up to 16 times than atmospheric levels). Large aphid populations also excrete significant amounts of honeydew, a waste product high in sugars. Based on 13C isotope tracing and genomic analyses, we showed that aphid-derived carbon found in CO2 and honeydew was recycled in gall tissues via photosynthesis and glycometabolism. These results indicated that the aphid-gall system evolved in a manner that allowed nutrient recycling, where the gall provides nutrients to the growing aphid population, and in turn, aphid-derived carbon metabolites provide a resource for the growth of the gall. The metabolic efficiency of this self-circulating system indicates that the input needed from the host plant to maintain aphid population growth less than previously thought and possibly minimal. Aside from the recycling of nutrients, we also found that gall metabolites were transported to other parts of the host plant and is particularly beneficial for leaves growing adjacent to the gall. Taken together, galls in the S. chinensis-Rhus chinensis system are highly specialized structures that serve as a metabolic and nutrient exchange hub that benefits both the aphid and its host plant. As such, host plants provide both shelter and nutrients to protect and sustain aphid populations, and in return, aphid-derived metabolites are channeled back to the host plant and thus provide a certain degree of "metabolic compensation" for their caloric and structural needs.
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Affiliation(s)
- Xiaoming Chen
- Research Institute of Resource Insects, Chinese Academy of Forestry, Kunming, China
- Key Laboratory of Breeding and Utilization of Resource Insects of State Forestry Administration, Kunming, China
| | - Zixiang Yang
- Research Institute of Resource Insects, Chinese Academy of Forestry, Kunming, China
- Key Laboratory of Breeding and Utilization of Resource Insects of State Forestry Administration, Kunming, China
| | - Hang Chen
- Research Institute of Resource Insects, Chinese Academy of Forestry, Kunming, China
- Key Laboratory of Breeding and Utilization of Resource Insects of State Forestry Administration, Kunming, China
| | - Qian Qi
- Research Institute of Resource Insects, Chinese Academy of Forestry, Kunming, China
- Key Laboratory of Breeding and Utilization of Resource Insects of State Forestry Administration, Kunming, China
| | - Juan Liu
- Research Institute of Resource Insects, Chinese Academy of Forestry, Kunming, China
- Key Laboratory of Breeding and Utilization of Resource Insects of State Forestry Administration, Kunming, China
| | - Chao Wang
- College of Horticulture and Landscape, Southwest Forestry University, Kunming, China
| | - Shuxia Shao
- Research Institute of Resource Insects, Chinese Academy of Forestry, Kunming, China
- Key Laboratory of Breeding and Utilization of Resource Insects of State Forestry Administration, Kunming, China
| | - Qin Lu
- Research Institute of Resource Insects, Chinese Academy of Forestry, Kunming, China
- Key Laboratory of Breeding and Utilization of Resource Insects of State Forestry Administration, Kunming, China
| | - Yang Li
- Research Institute of Resource Insects, Chinese Academy of Forestry, Kunming, China
| | - Haixia Wu
- Research Institute of Resource Insects, Chinese Academy of Forestry, Kunming, China
- Key Laboratory of Breeding and Utilization of Resource Insects of State Forestry Administration, Kunming, China
| | - Kirst King-Jones
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Ming-Shun Chen
- Department of Entomology, Kansas State University, Manhattan, KS, United States
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Feng H, Meng PP, Dou Q, Zhang SX, Wang HH, Wang CY. [Advances in mechanisms of nutrient exchange between mycorrhizal fungi and host plants]. Ying Yong Sheng Tai Xue Bao 2019; 30:3596-3604. [PMID: 31621248 DOI: 10.13287/j.1001-9332.201910.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Mycorrhizae, formed through the colonization of soil mycorrhizal fungi into the roots of host plants, are common symbiosis in the terrestrial ecosystems. The establishment of mycorrhizae is mainly based on the bidirectional nutrient exchanges between the symbiotic partners. Mycorrhizal fungi can absorb mineral nutrients, such as nitrogen and phosphorus, from soil and transport them to the host plants for their growth. As an exchange, host plants supply mycorrhizal fungi with the carbohydrates in the form of lipids or sugars, which are essential for fungal growth. In recent years, the mechanism of nutrient exchange between the mycorrhizal fungi and host plants has been a hot research topic. Important progresses have been achieved in mechanisms of host plants nutrient uptake and transport mediated by the mycorrhizal fungi. In this review, recent advances in nutrient exchange between arbuscular mycorrhizal fungi, ectomycorrhizal fungi and host plants were summarized, especially in the absorption and bidirectional transfer mechanisms of important nutrients, such as carbon, nitrogen and phosphorus. The potential regulatory effects of nutrient exchange in the mycorrhizal development were also reviewed. In addition, key problems and prospects of related researches were analyzed. This paper would be meaningful for the establishment of mycorrhizal model and the optimization of mycorrhizal effects.
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Affiliation(s)
- Huan Feng
- College of Forestry, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Pan-Pan Meng
- College of Forestry, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Qing Dou
- College of Forestry, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Shou-Xia Zhang
- College of Forestry, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Hai-Hua Wang
- College of Forestry, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Chun-Yan Wang
- College of Forestry, Northwest A&F University, Yangling 712100, Shaanxi, China
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Clark TJ, Friel CA, Grman E, Friesen ML, Shachar-Hill Y. Unfair trade underground revealed by integrating data with Nash bargaining models. New Phytol 2019; 222:1325-1337. [PMID: 30671951 DOI: 10.1111/nph.15703] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 01/08/2019] [Indexed: 06/09/2023]
Abstract
Mutually beneficial resource exchange is fundamental to global biogeochemical cycles and plant and animal nutrition. However, there is inherent potential conflict in mutualisms, as each organism benefits more when the exchange ratio ('price') minimizes its own costs and maximizes its benefits. Understanding the bargaining power that each partner has in these interactions is key to our ability to predict the exchange ratio and therefore the functionality of the cell, organism, community and ecosystem. We tested whether partners have symmetrical ('fair') or asymmetrical ('unfair') bargaining power in a legume-rhizobia nitrogen-fixing symbiosis using measurements of carbon and nitrogen dynamics in a mathematical modeling framework derived from economic theory. A model of symmetric bargaining power was not consistent with our data. Instead, our data indicate that the growth benefit to the plant (Medicago truncatula) has greater weight in determining trade dynamics than the benefit to the bacteria. Quantitative estimates of the relative power of the plant revealed that the plant's influence rises as soil nitrogen availability decreases and trade benefits to both partners increase. Our finding that M. truncatula legumes have more bargaining power than their rhizobial partner at lower nitrogen availabilities highlights the importance of context-dependence for the evolution of mutualism with increasing nutrient deposition.
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Affiliation(s)
- Teresa J Clark
- Department of Plant Biology, Michigan State University, 612 Wilson Rd., East Lansing, MI, 48824, USA
| | - Colleen A Friel
- Department of Plant Biology, Michigan State University, 612 Wilson Rd., East Lansing, MI, 48824, USA
| | - Emily Grman
- Department of Biology, Eastern Michigan University, 441 Mark Jefferson Science Complex, Ypsilanti, MI, 48197, USA
| | - Maren L Friesen
- Department of Plant Biology, Michigan State University, 612 Wilson Rd., East Lansing, MI, 48824, USA
- Department of Plant Pathology, Washington State University, Johnson Hall Rm 345, Pullman, WA, 99164, USA
- Department of Crop and Soil Sciences, Washington State University, Johnson Hall Rm 115, Pullman, WA, 99164, USA
| | - Yair Shachar-Hill
- Department of Plant Biology, Michigan State University, 612 Wilson Rd., East Lansing, MI, 48824, USA
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15
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Wang W, Shi J, Xie Q, Jiang Y, Yu N, Wang E. Nutrient Exchange and Regulation in Arbuscular Mycorrhizal Symbiosis. Mol Plant 2017; 10:1147-1158. [PMID: 28782719 DOI: 10.1016/j.molp.2017.07.012] [Citation(s) in RCA: 178] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 07/29/2017] [Accepted: 07/31/2017] [Indexed: 05/19/2023]
Abstract
Most land plants form symbiotic associations with arbuscular mycorrhizal (AM) fungi. These are the most common and widespread terrestrial plant symbioses, which have a global impact on plant mineral nutrition. The establishment of AM symbiosis involves recognition of the two partners and bidirectional transport of different mineral and carbon nutrients through the symbiotic interfaces within the host root cells. Intriguingly, recent discoveries have highlighted that lipids are transferred from the plant host to AM fungus as a major carbon source. In this review, we discuss the transporter-mediated transfer of carbon, nitrogen, phosphate, potassium and sulfate, and present hypotheses pertaining to the potential regulatory mechanisms of nutrient exchange in AM symbiosis. Current challenges and future perspectives on AM symbiosis research are also discussed.
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Affiliation(s)
- Wanxiao Wang
- College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, China; National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Jincai Shi
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Qiujin Xie
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Yina Jiang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Nan Yu
- College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, China.
| | - Ertao Wang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
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16
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Ankrah NYD, Luan J, Douglas AE. Cooperative Metabolism in a Three-Partner Insect-Bacterial Symbiosis Revealed by Metabolic Modeling. J Bacteriol 2017; 199:e00872-16. [PMID: 28348026 DOI: 10.1128/JB.00872-16] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 03/02/2017] [Indexed: 02/06/2023] Open
Abstract
An important factor determining the impact of microbial symbionts on their animal hosts is the balance between the cost of nutrients consumed by the symbionts and the benefit of nutrients released back to the host, but the quantitative significance of nutrient exchange in symbioses involving multiple microbial partners has rarely been addressed. In this study on the association between two intracellular bacterial symbionts, “Candidatus Portiera aleyrodidarum” and “Candidatus Hamiltonella defensa,” and their animal host, the whitefly Bemisia tabaci, we apply metabolic modeling to investigate host-symbiont nutrient exchange. Our in silico analysis revealed that >60% of the essential amino acids and related metabolites synthesized by “Candidatus Portiera aleyrodidarum” are utilized by the host, including a substantial contribution of nitrogen recycled from host nitrogenous waste, and that these interactions are required for host growth. In contrast, “Candidatus Hamiltonella defensa” retains most or all of the essential amino acids and B vitamins that it is capable of synthesizing. Furthermore, “Candidatus Hamiltonella defensa” suppresses host growth in silico by competition with “Candidatus Portiera aleyrodidarum” for multiple host nutrients, by suppressing “Candidatus Portiera aleyrodidarum” growth and metabolic function, and also by consumption of host nutrients that would otherwise be allocated to host growth. The interpretation from these modeling outputs that “Candidatus Hamiltonella defensa” is a nutritional parasite could not be inferred reliably from gene content alone but requires consideration of constraints imposed by the structure of the metabolic network. Furthermore, these quantitative models offer precise predictions for future experimental study and the opportunity to compare the functional organization of metabolic networks in different symbioses. IMPORTANCE The metabolic functions of unculturable intracellular bacteria with much reduced genomes are traditionally inferred from gene content without consideration of how the structure of the metabolic network may influence flux through metabolic reactions. The three-compartment model of metabolic flux between two bacterial symbionts and their insect host constructed in this study revealed that one symbiont is structured to overproduce essential amino acids for the benefit of the host, but the essential amino acid production in the second symbiont is quantitatively constrained by the structure of its network, rendering it “selfish” with respect to these nutrients. This study demonstrates the importance of quantitative flux data for elucidation of the metabolic function of symbionts. The in silico methodology can be applied to other symbioses with intracellular bacteria.
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Ishaq SL. Plant-microbial interactions in agriculture and the use of farming systems to improve diversity and productivity. AIMS Microbiol 2017; 3:335-353. [PMID: 31294165 PMCID: PMC6605018 DOI: 10.3934/microbiol.2017.2.335] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 05/04/2017] [Indexed: 11/18/2022] Open
Abstract
A thorough understanding of the services provided by microorganisms to the agricultural ecosystem is integral to understanding how management systems can improve or deteriorate soil health and production over the long term. Yet it is hampered by the difficulty in measuring the intersection of plant, microbe, and environment, in no small part because of the situational specificity to some plant-microbial interactions, related to soil moisture, nutrient content, climate, and local diversity. Despite this, perspective on soil microbiota in agricultural settings can inform management practices to improve the sustainability of agricultural production.
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Affiliation(s)
- Suzanne L Ishaq
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT 59717, Montana, USA
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Garcia K, Delaux PM, Cope KR, Ané JM. Molecular signals required for the establishment and maintenance of ectomycorrhizal symbioses. New Phytol 2015; 208:79-87. [PMID: 25982949 DOI: 10.1111/nph.13423] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 03/25/2015] [Indexed: 05/08/2023]
Abstract
Ectomycorrhizal (ECM) symbioses are among the most widespread associations between roots of woody plants and soil fungi in forest ecosystems. These associations contribute significantly to the sustainability and sustainagility of these ecosystems through nutrient cycling and carbon sequestration. Unfortunately, the molecular mechanisms controlling the mutual recognition between both partners are still poorly understood. Elegant work has demonstrated that effector proteins from ECM and arbuscular mycorrhizal (AM) fungi regulate host defenses by manipulating plant hormonal pathways. In parallel, genetic and evolutionary studies in legumes showed that a 'common symbiosis pathway' is required for the establishment of the ancient AM symbiosis and has been recruited for the rhizobia-legume association. Given that genes of this pathway are present in many angiosperm trees that develop ectomycorrhizas, we propose their potential involvement in some but not all ECM associations. The maintenance of a successful long-term relationship seems strongly regulated by resource allocation between symbiotic partners, suggesting that nutrients themselves may serve as signals. This review summarizes our current knowledge on the early and late signal exchanges between woody plants and ECM fungi, and we suggest future directions for decoding the molecular basis of the underground dance between trees and their favorite fungal partners.
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Affiliation(s)
- Kevin Garcia
- Department of Agronomy, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Pierre-Marc Delaux
- Department of Agronomy, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Kevin R Cope
- Department of Agronomy, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Jean-Michel Ané
- Department of Agronomy, University of Wisconsin-Madison, Madison, WI, 53706, USA
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Freeman CJ, Thacker RW, Baker DM, Fogel ML. Quality or quantity: is nutrient transfer driven more by symbiont identity and productivity than by symbiont abundance? ISME J 2013; 7:1116-25. [PMID: 23407307 PMCID: PMC3660684 DOI: 10.1038/ismej.2013.7] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Revised: 12/20/2012] [Accepted: 01/03/2013] [Indexed: 12/12/2022]
Abstract
By forming symbiotic interactions with microbes, many animals and plants gain access to the products of novel metabolic pathways. We investigated the transfer of symbiont-derived carbon and nitrogen to the sponges Aplysina cauliformis, Aplysina fulva, Chondrilla caribensis, Neopetrosia subtriangularis and Xestospongia bocatorensis, all of which host abundant microbial populations, and Niphates erecta, which hosts a sparse symbiont community. We incubated sponges in light and dark bottles containing seawater spiked with (13)C- and (15)N-enriched inorganic compounds and then measured (13)C and (15)N enrichment in the microbial (nutrient assimilation) and sponge (nutrient transfer) fractions. Surprisingly, although most sponges hosting abundant microbial communities were more enriched in (13)C than N. erecta, only N. subtriangularis was more enriched in (15)N than N. erecta. Although photosymbiont abundance varied substantially across species, (13)C and (15)N enrichment was not significantly correlated with photosymbiont abundance. Enrichment was significantly correlated with the ratio of gross productivity to respiration (P:R), which varied across host species and symbiont phylotype. Because irradiance impacts P:R ratios, we also incubated A. cauliformis in (13)C-enriched seawater under different irradiances to determine whether symbiont carbon fixation and transfer are dependent on irradiance. Carbon fixation and transfer to the sponge host occurred in all treatments, but was greatest at higher irradiances and was significantly correlated with P:R ratios. Taken together, these results demonstrate that nutrient transfer from microbial symbionts to host sponges is influenced more by host-symbiont identities and P:R ratios than by symbiont abundance.
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Délano-Frier JP, Tejeda-Sartorius M. Unraveling the network: Novel developments in the understanding of signaling and nutrient exchange mechanisms in the arbuscular mycorrhizal symbiosis. Plant Signal Behav 2008; 3:936-44. [PMID: 19513196 PMCID: PMC2633739 DOI: 10.4161/psb.6789] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2008] [Accepted: 08/15/2008] [Indexed: 05/20/2023]
Abstract
The arbuscular mycorrhhiza (AM) symbiosis involves an intricate network of signaling and biochemical pathways designed to ensure that a beneficial relationship is established between the plant and fungal partners as a result of a mutual nutrient exchange. Emerging data has been recently published to explain why the relationship is not always fair, as observed in prevalent parasitic AM relationships in which the plant host receives no phosphorus (P) in exchange for carbon (C) delivered to the fungus. The theory behind this unorthodox view of the AM relationship, together with the description of other recent developments in nutrient mobilization as well as in key aspects of the bi-directional signaling that culminates in the symbiotic association, is the subject of this review.
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Affiliation(s)
- John Paul Délano-Frier
- Unidad de Biotecnología e Ingeniería Genética de Plantas; Cinvestav-Campus Guanajuato; Irapuato, Guanajuato México
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