Expression of the nitrate transporter nrt2 gene from the symbiotic basidiomycete Hebeloma cylindrosporum is affected by host plant and carbon sources

Rekangalt, David; Pepin, Régis; Verner, Marie-Christine; Debaud, Jean‐Claude; Marmeisse, Roland; Fraissinet‐Tachet, Laurence

doi:10.1007/s00572-008-0221-2

Cited by 7 publications

(6 citation statements)

References 37 publications

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“…It is proposed that (1) nitrate availability stimulates the expression of the identified nitrate transporter (most likely together with other high-or low-affinity nitrate transporters), and presumably also of nitrate reductase, although we were unable to clone the enzyme sequence reported previously (Kaldorf et al, 1998;Montanini et al, 2006;Rekangalt et al, 2009); (2) ammonium stimulates the expression of the GS/GOGAT pathway, and increasing levels of Gln and Glu rather than ammonium could lead to an up-regulation of Arg synthesis genes (Hinnebusch, 1988;ter Schure et al, 2000); (3) Arg is then translocated from the ERM to the IRM (Cruz et al, 2007); (4) elevated Arg levels trigger an increase in arginase and urease activities in the IRM but not in the ERM (the difference between IRM and ERM may be due to N catabolite repression in the ERM [Hinnebusch, 1988;Wagemaker et al, 2007], as amino acid levels are substantial in the ERM in the presence of N ); (5) Arg or Orn that is produced in the IRM by the action of arginase stimulates the expression and activity of OAT (Messenguy et al, 2000;ter Schure et al, 2000); (6) the subsequent release of ammonium in the IRM could stimulate the passive efflux of ammonia into the mycorrhizal interface and the uptake of ammonium by the plant by specific transporters (Selle et al, 2005;Gomez et al, 2009;Guether et al, 2009); and (7) the subsequent increase in the availability of ammonium for the host causes an up-regulation of plant GS, especially near the sites of N transfer .…”

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confidence: 66%

Regulation of the Nitrogen Transfer Pathway in the Arbuscular Mycorrhizal Symbiosis: Gene Characterization and the Coordination of Expression with Nitrogen Flux

et al. 2010

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The arbuscular mycorrhiza (AM) brings together the roots of over 80% of land plant species and fungi of the phylum Glomeromycota and greatly benefits plants through improved uptake of mineral nutrients. AM fungi can take up both nitrate and ammonium from the soil and transfer nitrogen (N) to host roots in nutritionally substantial quantities. The current model of N handling in the AM symbiosis includes the synthesis of arginine in the extraradical mycelium and the transfer of arginine to the intraradical mycelium, where it is broken down to release N for transfer to the host plant. To understand the mechanisms and regulation of N transfer from the fungus to the plant, 11 fungal genes putatively involved in the pathway were identified from Glomus intraradices, and for six of them the full-length coding sequence was functionally characterized by yeast complementation. Two glutamine synthetase isoforms were found to have different substrate affinities and expression patterns, suggesting different roles in N assimilation. The spatial and temporal expression of plant and fungal N metabolism genes were followed after nitrate was added to the extraradical mycelium under N-limited growth conditions using hairy root cultures. In parallel experiments with 15 N, the levels and labeling of free amino acids were measured to follow transport and metabolism. The gene expression pattern and profiling of metabolites involved in the N pathway support the idea that the rapid uptake, translocation, and transfer of N by the fungus successively trigger metabolic gene expression responses in the extraradical mycelium, intraradical mycelium, and host plant.

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confidence: 66%

Regulation of the Nitrogen Transfer Pathway in the Arbuscular Mycorrhizal Symbiosis: Gene Characterization and the Coordination of Expression with Nitrogen Flux

et al. 2010

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“…However, ECM fungi differ in their ability to absorb NO3 -from the soil, and some ECM fungi have been shown to produce a greater biomass when supplied with NO3 -compared to NH4 + [107]. However, a supply of NH4 + leads to a down-regulation of a NO3 -transporter and a nitrate reductase of Hebeloma cylindrosporum, what suggests that also ECM fungi generally prefer NH4 + over NO3 - [1,108,109].…”

Section: Uptake Of Nitrogen From the Soilmentioning

confidence: 99%

The Role of the Mycorrhizal Symbiosis in Nutrient Uptake of Plants and the Regulatory Mechanisms Underlying These Transport Processes

Bücking¹,

Liepold²,

Ambilwade³

2012

Plant Science

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“…The fact that NH 4 + was added to all treatments, including the controls, indicates that the down-regulation of NT in the ERM after the supply of sucrose to the RC was the result of an increase in internal levels of NH 4 + or a downstream metabolite, rather than a response to the exogenous NH 4 + supply. Interestingly, the NO 3 − transporter nrt2 of the ectomycorrhizal basidiomycete Hebeloma cylindrosporum is up-regulated in response to a supply with different C sources (27), although a simultaneous supply with NH 4 + reduces the effect. GS1, GS2, and GluS were up-regulated in response to higher C levels.…”

Section: Nhmentioning

confidence: 99%

Carbon availability triggers fungal nitrogen uptake and transport in arbuscular mycorrhizal symbiosis

Fellbaum

Gachomo

Beesetty

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

362

257

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The arbuscular mycorrhizal (AM) symbiosis, formed between the majority of land plants and ubiquitous soil fungi of the phylum Glomeromycota, is responsible for massive nutrient transfer and global carbon sequestration. AM fungi take up nutrients from the soil and exchange them against photosynthetically fixed carbon (C) from the host. Recent studies have demonstrated that reciprocal reward strategies by plant and fungal partners guarantee a "fair trade" of phosphorus against C between partners [Kiers ET, et al. (2011) Science 333:880-882], but whether a similar reward mechanism also controls nitrogen (N) flux in the AM symbiosis is not known. Using mycorrhizal root organ cultures, we manipulated the C supply to the host and fungus and followed the uptake and transport of N sources in the AM symbiosis, the enzymatic activities of arginase and urease, and fungal gene expression in the extraradical and intraradical mycelium. We found that the C supply of the host plant triggers the uptake and transport of N in the symbiosis, and that the increase in N transport is orchestrated by changes in fungal gene expression. N transport in the symbiosis is stimulated only when the C is delivered by the host across the mycorrhizal interface, not when C is supplied directly to the fungal extraradical mycelium in the form of acetate. These findings support the importance of C flux from the root to the fungus as a key trigger for N uptake and transport and provide insight into the N transport regulation in the AM symbiosis.arbuscular mycorrhiza | arginine catabolism | carbon transport | Glomus intraradices | urea cycle T he arbuscular mycorrhizal (AM) symbiosis plays a key role in nutrient uptake in the majority of land plants, including such important crop species as corn, soybean, and rice. The AM symbiosis can increase the uptake of phosphate (P) and nitrogen (N), as well as of trace elements such as copper and zinc, and improves the abiotic and biotic stress resistance of the host (2). Previous work has focused primarily on the transport of P in AM symbiosis, but more recent work has highlighted the potential importance of N uptake by fungal symbionts (3, 4). The extraradical mycelium (ERM) of the fungus is able to take up NH 4 + (5, 6), NO 3 − (5-7), and organic N resources (3-5) from the soil and to transfer N to the host. The high mobility of N in the soil has raised the question of whether AM fungi can contribute significantly to the N nutrition of the host (8). It has been suggested that an improved N status of mycorrhizal plants may be simply a consequence of an improved P nutrition (9); however, other studies have demonstrated that AM fungi can deliver substantial amounts of N to the host, with an estimated 21% of total N taken up by the fungal ERM in root organ cultures (10) and 74% of the total N in the leaves of Zea mays coming from the fungal ERM with access to urea (11).Current models of N transport in the AM symbiosis involve uptake of inorganic N from the soil and N assimilation via the anabolic arm of the urea...

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Expression of the nitrate transporter nrt2 gene from the symbiotic basidiomycete Hebeloma cylindrosporum is affected by host plant and carbon sources

Cited by 7 publications

References 37 publications

Regulation of the Nitrogen Transfer Pathway in the Arbuscular Mycorrhizal Symbiosis: Gene Characterization and the Coordination of Expression with Nitrogen Flux

Regulation of the Nitrogen Transfer Pathway in the Arbuscular Mycorrhizal Symbiosis: Gene Characterization and the Coordination of Expression with Nitrogen Flux

The Role of the Mycorrhizal Symbiosis in Nutrient Uptake of Plants and the Regulatory Mechanisms Underlying These Transport Processes

Carbon availability triggers fungal nitrogen uptake and transport in arbuscular mycorrhizal symbiosis

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