Molecular and cell biology of arbuscular mycorrhizal symbiosis

Hause, Bettina; Fester, Thomas

doi:10.1007/s00425-004-1436-x

Cited by 145 publications

(92 citation statements)

References 154 publications

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“…2n, for comparison see also Bonfante-Fasolo 1984). This supports the widely accepted hypothesis that the AM fungal arbuscule and the enhanced metabolism of the arbusculated cell (Hause and Fester 2005;Franken 2010) consume all carbohydrates that enter the cell and prevent starch accumulation (Gutjahr et al 2009). However, since our morphological analysis offers only a snapshot of the colonization events, we cannot exclude that starch might have already accumulated in a root cortex cell before it was colonized by an arbuscule.…”

Section: Morphology and Intensity Of Mycorrhizal Colonizationsupporting

confidence: 85%

Root starch accumulation in response to arbuscular mycorrhizal colonization differs among Lotus japonicus starch mutants

Gutjahr

Novero

Welham

et al. 2011

Planta

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Arbuscular mycorrhizal (AM) fungi are obligate symbionts dependent for completion of their life cycle on plant carbohydrates, which they trade for mineral nutrients. Plant colonization by AM fungi is therefore expected to induce profound changes in plant carbon metabolism. We have previously observed that on one hand starch accumulation increases in responses to pre-symbiotic fungal signals and on the other hand, it decreases in mycorrhizal Lotus japonicus roots (Gutjahr et al. in New Phytol 183:53-61, 2009). To examine the importance of starch metabolism for AM development, we took advantage of a novel series of Lotus japonicus mutants impaired either in starch degradation or in synthesis. Normal AM colonization in all mutants indicated that defects in starch metabolism do not affect AM development and that carbohydrates can be supplied to the AM fungus without a requirement for starch synthesis. Furthermore, our experiments allowed us to characterize root starch dynamics in detail and point to continued turnover of starch in the degradation mutants in the presence of mycorrhiza.

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Section: Morphology and Intensity Of Mycorrhizal Colonizationsupporting

confidence: 85%

Root starch accumulation in response to arbuscular mycorrhizal colonization differs among Lotus japonicus starch mutants

Gutjahr

Novero

Welham

et al. 2011

Planta

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“…Fungal mutualists confer a wide range of benefits to their hosts (Porras-Alfaro & Bayman, 2011), including enhanced host disease resistance (Djonović et al, 2007;Pozo & Azcó nAguilar, 2007;Viterbo et al, 2007), drought tolerance (Hause & Fester, 2005), improved nutrient uptake and Trichoderma NRPSs growth (Balestrini & Lanfranco, 2006;Martin et al, 2007;Chacó n et al, 2007), and protection against invertebrate and vertebrate herbivory (Clay & Schardl, 2002). The expression of induced defences is mediated by complex signalling networks in which the plant hormones JA and SA play key roles (Smith et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

Functional analysis of non-ribosomal peptide synthetases (NRPSs) in Trichoderma virens reveals a polyketide synthase (PKS)/NRPS hybrid enzyme involved in the induced systemic resistance response in maize

et al. 2012

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Trichoderma virens genome harbours genes encoding 22 non-ribosomal peptide synthetases (NRPSs) with at least one complete module (containing adenylation, thiolation and condensation domains) and four PKS/NRPS (polyketide synthase/NRPS) hybrid enzymes. After a primary screen for expression of these 26 genes when mycelia of T. virens are in contact with maize roots, seven genes that are upregulated were selected for further study. Using homologous recombination, loss-of-function mutants in six of these were obtained (the seventh, tex2, was acquired from our previous studies). Plant assays in a hydroponics system revealed that all seven mutants retained the ability to internally colonize maize roots. However, a mutation in one of the PKS/NRPS hybrid genes impaired the ability of T. virens to induce the defence response gene pal (phenylalanine ammonia lyase), suggesting a putative role for the associated metabolite product in induced systemic resistance. Interestingly, the mutant retained its ability to induce another defence response gene aos (allene oxide synthase). We thus provide evidence that a PKS/NRPS hybrid enzyme is involved in Trichoderma-plant interactions resulting in induction of defence responses.

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“…NH 3 /NH 4 + is then translocated by so far unknown mechanisms (transporter, diffusion, or vesicle mediated) into the periarbuscular space, where, due to the acidic environment, its ratio shifts toward NH 4 + (.99.99%). b, The acidity of the interfacial apoplast is established by plant and fungal H + -ATPases (Hause and Fester, 2005;Balestrini et al, 2007), thus providing the energy for H + -dependent transport processes. c, The NH 4 + ion is deprotonated prior to its transport across the plant membrane via the LjAMT2;2 protein and released in its uncharged NH 3 form into the plant cytoplasm.…”

Section: Ammonium and Phosphate Uptake At The Interface: A Speculativmentioning

confidence: 99%

A Mycorrhizal-Specific Ammonium Transporter from Lotus japonicus Acquires Nitrogen Released by Arbuscular Mycorrhizal Fungi

et al. 2009

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In mycorrhizal associations, the fungal partner assists its plant host by providing nitrogen (N) in addition to phosphate. Arbuscular mycorrhizal (AM) fungi have access to inorganic or organic forms of N and translocate them via arginine from the extra-to the intraradical mycelium, where the N is transferred to the plant without any carbon skeleton. However, the molecular form in which N is transferred, as well as the involved mechanisms, is still under debate. NH 4 + seems to be the preferential transferred molecule, but no plant ammonium transporter (AMT) has been identified so far. Here, we offer evidence of a plant AMT that is involved in N uptake during mycorrhiza symbiosis. The gene LjAMT2;2, which has been shown to be the highest up-regulated gene in a transcriptomic analysis of Lotus japonicus roots upon colonization with Gigaspora margarita, has been characterized as a high-affinity AMT belonging to the AMT2 subfamily. It is exclusively expressed in the mycorrhizal roots, but not in the nodules, and transcripts have preferentially been located in the arbusculated cells. Yeast (Saccharomyces cerevisiae) mutant complementation has confirmed its functionality and revealed its dependency on acidic pH. The transport experiments using Xenopus laevis oocytes indicated that, unlike other plant AMTs, LjAMT2;2 transports NH 3 instead of NH 4 + . Our results suggest that the transporter binds charged ammonium in the apoplastic interfacial compartment and releases the uncharged NH 3 into the plant cytoplasm. The implications of such a finding are discussed in the context of AM functioning and plant phosphorus uptake.

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Molecular and cell biology of arbuscular mycorrhizal symbiosis

Cited by 145 publications

References 154 publications

Root starch accumulation in response to arbuscular mycorrhizal colonization differs among Lotus japonicus starch mutants

Root starch accumulation in response to arbuscular mycorrhizal colonization differs among Lotus japonicus starch mutants

Functional analysis of non-ribosomal peptide synthetases (NRPSs) in Trichoderma virens reveals a polyketide synthase (PKS)/NRPS hybrid enzyme involved in the induced systemic resistance response in maize

A Mycorrhizal-Specific Ammonium Transporter from Lotus japonicus Acquires Nitrogen Released by Arbuscular Mycorrhizal Fungi

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