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Abstract
Phosphorous is important for life but often limiting for plants. The symbiotic pathway of phosphate uptake via arbuscular mycorrhizal fungi (AMF) is evolutionarily ancient and today occurs in natural and agricultural ecosystems alike. Plants capable of this symbiosis can obtain up to all of the phosphate from symbiotic fungi, and this offers potential means to develop crops less dependent on unsustainable P fertilizers. Here, we review the mechanisms and insights gleaned from the fine-tuned signal exchanges that orchestrate the intimate mutualistic symbiosis between plants and AMF. As the currency of trade, nutrients have signaling functions beyond being the nutritional goal of mutualism. We propose that such signaling roles and metabolic reprogramming may represent commitments for a mutualistic symbiosis that act across the stages of symbiosis development.
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Affiliation(s)
- Chai Hao Chiu
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
| | - Uta Paszkowski
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
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Lanfranco L, Fiorilli V, Gutjahr C. Partner communication and role of nutrients in the arbuscular mycorrhizal symbiosis. THE NEW PHYTOLOGIST 2018; 220:1031-1046. [PMID: 29806959 DOI: 10.1111/nph.15230] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 04/11/2018] [Indexed: 05/20/2023]
Abstract
Contents Summary 1031 I. Introduction 1031 II. Interkingdom communication enabling symbiosis 1032 III. Nutritional and regulatory roles for key metabolites in the AM symbiosis 1035 IV. The plant-fungus genotype combination determines the outcome of the symbiosis 1039 V. Perspectives 1039 Acknowledgements 1041 References 1041 SUMMARY: The evolutionary and ecological success of the arbuscular mycorrhizal (AM) symbiosis relies on an efficient and multifactorial communication system for partner recognition, and on a fine-tuned and reciprocal metabolic regulation of each symbiont to reach an optimal functional integration. Besides strigolactones, N-acetylglucosamine-derivatives released by the plant were recently suggested to trigger fungal reprogramming at the pre-contact stage. Remarkably, N-acetylglucosamine-based diffusible molecules also are symbiotic signals produced by AM fungi (AMF) and clues on the mechanisms of their perception by the plant are emerging. AMF genomes and transcriptomes contain a battery of putative effector genes that may have conserved and AMF- or host plant-specific functions. Nutrient exchange is the key feature of AM symbiosis. A mechanism of phosphate transport inside fungal hyphae has been suggested, and first insights into the regulatory mechanisms of root colonization in accordance with nutrient transfer and status were obtained. The recent discovery of the dependency of AMF on fatty acid transfer from the host has offered a convincing explanation for their obligate biotrophism. Novel studies highlighted the importance of plant and fungal genotypes for the outcome of the symbiosis. These findings open new perspectives for fundamental research and application of AMF in agriculture.
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Affiliation(s)
- Luisa Lanfranco
- Department of Life Sciences and Systems Biology, University of Torino, Viale P.A. Mattioli 25, 10125, Torino, Italy
| | - Valentina Fiorilli
- Department of Life Sciences and Systems Biology, University of Torino, Viale P.A. Mattioli 25, 10125, Torino, Italy
| | - Caroline Gutjahr
- Plant Genetics, School of Life Sciences Weihenstephan, Technical University of Munich (TUM), Emil Ramann Str. 4, D-85354, Freising, Germany
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Labidi S, Jeddi FB, Tisserant B, Yousfi M, Sanaa M, Dalpé Y, Sahraoui ALH. Field application of mycorrhizal bio-inoculants affects the mineral uptake of a forage legume (Hedysarum coronarium L.) on a highly calcareous soil. MYCORRHIZA 2015; 25:297-309. [PMID: 25323044 DOI: 10.1007/s00572-014-0609-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 10/03/2014] [Indexed: 06/04/2023]
Abstract
The efficiency of two mycorrhizal bio-inoculants on the mineral uptake during the growth stages of a Mediterranean forage legume sulla (Hedysarum coronarium L.) was studied in the field on a highly calcareous soil. The first inoculum (Mm) was made up of a mixture of native arbuscular mycorrhizal fungi (AMF) isolated from calcareous soils: Septoglomus constrictum, Funneliformis geosporum, Glomus fuegianum, Rhizophagus irregularis and Glomus sp. The second was a commercial inoculum (Mi) containing one AMF species: R. irregularis. Both mycorrhizal inoculants increased total and arbuscular colonization of sulla roots. Inoculation with Mm showed a positive effect on sulla shoot dry weight (SDW) when compared to Mi and non-inoculated plants (control). Mineral contents (P, Mg, Mn, Fe) were higher in the shoots of sulla plants cultivated on mycorrhiza-inoculated plots compared to non-inoculated ones. This enhancement was observed during the flowering stage for P, Mg and Mn and during the rosette stage for Fe. An increase in P content of 50 % in plants inoculated with Mm compared to non-inoculated ones may be explained by the induction of root alkaline and acid phosphatase activities. Higher efficiency of native AMF species adapted to calcareous soils opens the way towards the development of mycorrhiza bio-fertilizers targeted to improve sustainable fertilization management in such soils.
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Affiliation(s)
- S Labidi
- Laboratoire des Sciences Horticoles, Institut National Agronomique de Tunisie, Université de Carthage, 43 Ave Charles Nicolle, 1082, Tunis, Mahrajène, Tunisie
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Functional characterisation and transcript analysis of an alkaline phosphatase from the arbuscular mycorrhizal fungus Funneliformis mosseae. Fungal Genet Biol 2013; 54:52-9. [DOI: 10.1016/j.fgb.2013.02.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 02/24/2013] [Indexed: 11/20/2022]
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Funamoto R, Saito K, Oyaizu H, Saito M, Aono T. Simultaneous in situ detection of alkaline phosphatase activity and polyphosphate in arbuscules within arbuscular mycorrhizal roots. FUNCTIONAL PLANT BIOLOGY : FPB 2007; 34:803-810. [PMID: 32689408 DOI: 10.1071/fp06326] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2006] [Accepted: 06/06/2007] [Indexed: 06/11/2023]
Abstract
Inorganic phosphate (Pi) metabolism in arbuscules of arbuscular mycorrhizal (AM) fungi is not well understood, although recent research has revealed that host plants absorb Pi around arbuscules with mycorrhiza-specific transporters. Therefore, we analysed the localisation of polyphosphate (polyP) and alkaline phosphatase (ALP) activity in arbuscules, which could be indicators of Pi metabolism. We developed a dual-labelling method for polyP and ALP activity, i.e. first labelling with fluorescent probes 4',6-diamidino-2-phenyl-indole dihydrochloride (DAPI) and then labelling with enzyme-labelled fluorescence (ELF97). The dual-labelling method made it possible to observe polyP and ALP activity signals simultaneously in mycorrhizal roots. The dual-labelling method revealed that ALP activity was mainly observed in mature arbuscules where polyP was rarely observed. The expression of the AM fungal ALP gene was suppressed in the knockdown plants of an AM-inducible Pi-transporter, and there was much polyP in arbuscules that showed low ALP activity. These topological observations suggest that there may be some relationships between polyP metabolism and ALP activity in arbuscules, and that these are, in part, controlled by Pi uptake by plants via the AM-inducible Pi-transporter.
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Affiliation(s)
- Rintaro Funamoto
- Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Katsuharu Saito
- Faculty of Agriculture, Shinshu University, 8304 Minami-minowa, Nagano 399-4598, Japan
| | - Hiroshi Oyaizu
- Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Masanori Saito
- Department of Environmental Chemistry, National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan
| | - Toshihiro Aono
- Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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Javot H, Pumplin N, Harrison MJ. Phosphate in the arbuscular mycorrhizal symbiosis: transport properties and regulatory roles. PLANT, CELL & ENVIRONMENT 2007; 30:310-322. [PMID: 17263776 DOI: 10.1111/j.1365-3040.2006.01617.x] [Citation(s) in RCA: 180] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
In response to the colonization by arbuscular mycorrhizal (AM) fungi, plants reprioritize their phosphate (Pi)-uptake strategies to take advantage of nutrient transfer via the fungus. The mechanisms underlying Pi transport are beginning to be understood, and recently, details of the regulation of plant and fungal Pi transporters in the AM symbiosis have been revealed. This review summarizes recent advances in this area and explores current data and hypotheses of how the plant Pi status affects the symbiosis. Finally, suggestions of an interrelationship of Pi and nitrogen (N) in the AM symbiosis are discussed.
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Affiliation(s)
- Hélène Javot
- Boyce Thompson Institute for Plant Research, Tower Road, Ithaca, NY, 14850, USA
| | - Nathan Pumplin
- Boyce Thompson Institute for Plant Research, Tower Road, Ithaca, NY, 14850, USA
| | - Maria J Harrison
- Boyce Thompson Institute for Plant Research, Tower Road, Ithaca, NY, 14850, USA
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Javot H, Penmetsa RV, Terzaghi N, Cook DR, Harrison MJ. A Medicago truncatula phosphate transporter indispensable for the arbuscular mycorrhizal symbiosis. Proc Natl Acad Sci U S A 2007; 104:1720-5. [PMID: 17242358 PMCID: PMC1785290 DOI: 10.1073/pnas.0608136104] [Citation(s) in RCA: 399] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2006] [Indexed: 11/18/2022] Open
Abstract
The arbuscular mycorrhizal (AM) symbiosis is a mutualistic endosymbiosis formed by plant roots and AM fungi. Most vascular flowering plants have the ability to form these associations, which have a significant impact on plant health and consequently on ecosystem function. Nutrient exchange is a central feature of the AM symbiosis, and AM fungi obtain carbon from their plant host while assisting the plant with the acquisition of phosphorus (as phosphate) from the soil. In the AM symbiosis, the fungus delivers P(i) to the root through specialized hyphae called arbuscules. The molecular mechanisms of P(i) and carbon transfer in the symbiosis are largely unknown, as are the mechanisms by which the plant regulates the symbiosis in response to its nutrient status. Plants possess many classes of P(i) transport proteins, including a unique clade (Pht1, subfamily I), members of which are expressed only in the AM symbiosis. Here, we show that MtPT4, a Medicago truncatula member of subfamily I, is essential for the acquisition of P(i) delivered by the AM fungus. However, more significantly, MtPT4 function is critical for AM symbiosis. Loss of MtPT4 function leads to premature death of the arbuscules; the fungus is unable to proliferate within the root, and symbiosis is terminated. Thus, P(i) transport is not only a benefit for the plant but is also a requirement for the AM symbiosis.
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Affiliation(s)
- Hélène Javot
- *Boyce Thompson Institute for Plant Research, Cornell University, Tower Road, Ithaca, NY 14850; and
| | - R. Varma Penmetsa
- Department of Plant Pathology, University of California, One Shields Avenue, Davis, CA 95616
| | - Nadia Terzaghi
- Department of Plant Pathology, University of California, One Shields Avenue, Davis, CA 95616
| | - Douglas R. Cook
- Department of Plant Pathology, University of California, One Shields Avenue, Davis, CA 95616
| | - Maria J. Harrison
- *Boyce Thompson Institute for Plant Research, Cornell University, Tower Road, Ithaca, NY 14850; and
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Stewart LI, Jabaji-Hare S, Driscoll BT. Effects of external phosphate concentration on glucose-6-phosphate dehydrogenase gene expression in the arbuscular mycorrhizal fungus Glomus intraradices. Can J Microbiol 2006; 52:823-30. [PMID: 17110974 DOI: 10.1139/w06-038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Specific primers were developed to amplify a 227 bp segment of the arbuscular mycorrhizal fungus Glomus intraradices gene encoding glucose-6-phosphate dehydrogenase (G6PDH), an enzyme involved in the pentose phosphate pathway. G6PDH gene expression was measured by real-time quantitative reverse transcriptase – polymerase chain reaction in response to phosphorus (P) concentrations in the growth medium of colonized transformed carrot roots. We investigated the effects of different P concentration treatments on carbon (C) metabolism within the intraradical mycelia of G. intraradices. The results showed a significant (P = 0.017) down-regulation of G6PDH expression in the intraradical mycelia of G. intraradices cultures grown in high P than low P conditions but no significant difference in regulation in excessive P concentrations when compared with the low P or high P concentrations. These results indicate that a reduction in the C flow from the host could be occurring as a result of elevated P and that a decrease in fungal G6PDH gene expression occurs, but not in the short term (less than 2 h). Reduced C flow from the host could lead to reduced fungal growth and root colonization, as was observed under high soil P conditions.Key words: arbuscular mycorrhizal fungi, phosphorus, nutrient uptake, glucose-6-phosphate dehydrogenase, gene expression.
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Affiliation(s)
- L I Stewart
- Microbiology Unit, Department of Natural Resources Sciences, McGill University, Ste-Anne-de-Bellevue, QC, Canada
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Ohtomo R, Saito M. Polyphosphate dynamics in mycorrhizal roots during colonization of an arbuscular mycorrhizal fungus. THE NEW PHYTOLOGIST 2005; 167:571-8. [PMID: 15998407 DOI: 10.1111/j.1469-8137.2005.01425.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Inorganic polyphosphate (poly P) has been considered to be a translocatable form of phosphate (Pi) in arbuscular mycorrhizal fungi (AMF). Here we examined time-course changes in poly P content during the AMF colonization process. Onion (Allium cepa) plants were cultured with or without inoculation with Gigaspora margarita for 2-8 wk with periodic sampling. Poly P in the extracts, purified through gel filtration, was quantified by the reverse reaction of polyphosphate kinase. The length of poly P in mycorrhizal roots appeared to be shorter than in extraradical hyphae or in spores of the AMF, indicating that AMF depolymerize poly P before providing Pi to the host. The poly P content increased as colonization proceeded, and was highly correlated with the weight of the colonized roots. These results support the model that AMF supply Pi to the host through the poly P pool, and that the poly P content of a mycorrhizal root can be a good indicator of the Pi-supplying activity of AMF.
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Affiliation(s)
- Ryo Ohtomo
- National Institute of Livestock and Grassland Science, 768 Senbon-matsu, Nasu-shiobara, Tochigi, 329-2793 Japan.
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