Evidence that differences in phosphate metabolism in mycorrhizas formed by species of <i>Glomus</i> and <i>Gigaspora</i> might be related to their life‐cycle strategies

Boddington, Claire L.; Dodd, J.

doi:10.1046/j.1469-8137.1999.00422.x

Cited by 85 publications

(51 citation statements)

References 34 publications

(44 reference statements)

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“…In this medium, as well as in compost, sus1-1 and sus3-1 mutants were not visibly different from wild-type plants. Although Terragreen has been reported to be inert in some publications (Boddington and Dodd, 1999), others (Edwards et al, 1998) and our own investigations have shown that this is not the case. It has substantial amounts of available nitrogen (equivalent to 99.5 kg N ha 21 ) and excessive amounts of sulfur (213 mg L 21 ).…”

Section: Sus3-1 Mutants Show Symptoms Of Nitrogen Starvation Under Cementioning

confidence: 55%

TILLING Mutants of Lotus japonicus Reveal That Nitrogen Assimilation and Fixation Can Occur in the Absence of Nodule-Enhanced Sucrose Synthase

Horst

Welham

Kelly³

et al. 2007

Plant Physiology

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In all plant species studied to date, sucrose synthase occurs as multiple isoforms. The specific functions of the different isoforms are for the most part not clear. Six isoforms of sucrose synthase have been identified in the model legume Lotus japonicus, the same number as in Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa). The genes encoding these isoforms are differentially expressed in all plant organs examined, although one, LjSUS4, is only expressed in flowers. LjSUS1 is the most highly expressed in all plant organs tested, except root nodules, where LjSUS3 accounts for more than 60% of the total SUS transcripts. One gene, LjSUS2, produces two transcripts due to alternative splicing, a feature not observed in other species to date. We have isolated plants carrying ethyl methanesulfonate-induced mutations in several SUS genes by targeting-induced local lesions in genomes reverse genetics and examined the effect of null alleles of two genes, LjSUS1 and LjSUS3, on nodule function. No differences were observed between the mutants and wild-type plants under glasshouse conditions, but there was evidence for a nitrogenstarvation phenotype in the sus3-1 mutant and severe impairment of growth in the sus1-1/sus3-1 double mutant under specific environmental conditions. Nodules of sus3-1 mutant plants retained a capacity for nitrogen fixation under all conditions. Thus, nitrogen fixation can occur in L. japonicus nodules even in the absence of LjSUS3 (the major nodule-induced isoform of SUS), so LjSUS1 must also contribute to the maintenance of nitrogen assimilation.

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Section: Sus3-1 Mutants Show Symptoms Of Nitrogen Starvation Under Cementioning

confidence: 55%

TILLING Mutants of Lotus japonicus Reveal That Nitrogen Assimilation and Fixation Can Occur in the Absence of Nodule-Enhanced Sucrose Synthase

Horst

Welham

Kelly³

et al. 2007

Plant Physiology

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“…Furthermore, Boddington and Dodd (1999) reported differences in the amount of polyP occurring in hyphae of different AM fungal species. This interesting observation requires to be confirmed, because the sensitivity and specificity of the stain used to visualize polyP (DAPI) has not yet been evaluated in filamentous fungi.…”

Section: P Transport Along Hyphaementioning

confidence: 99%

Untitled

2002

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The arbuscular mycorrhizal symbiosis is mutualistic, based on reciprocal transfer of P from the fungus to the plant and carbon from the plant to the fungus. Thus P is a most important 'currency' in the symbiosis. After absorbing P from the soil solution, the fungi first incorporate it into the cytosolic pool, and the excess P is transferred to the vacuoles. The vacuolar P pool probably plays a central role in P supply to the plant. The main forms of inorganic P in fungal vacuoles are orthophosphate and polyphosphate, but organic P molecules may also be present. Long distance translocation of P from the site of uptake in the external mycelium to the site of transfer to the plant is probably achieved via transfer of vacuolar components. This transport would be mediated either by protoplasmic streaming or the motile tubular vacuole-like system. The site of release of P into the interfacial apoplast and thence to the plant is most probably the fungal arbuscules. The biochemical and biophysical processes involved in P metabolism and transfer between cellular compartments in the symbiosis are currently not well understood. Some recent investigations of substrate specificities of phosphatase-type enzymes in AM fungi and other eukaryotic microorganisms, however, have shed new light on earlier results and permit the construction of a 1 hypothetical scheme of P-flow, including possible regulatory factors. Steps in this scheme are experimentally testable and should stimulate future research.

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“…It has been hypothesized that ACP could be involved in the hydrolysis of vacuolar polyphosphate after which inorganic P could be released by the fungus into the plant-fungal interface (Ezawa, Smith & Smith 2001). The presence of ACP activity has also been demonstrated in extraradical mycelium (van Aarle, Olsson & So¨derstro¨m 2001) and alkaline phosphatase (ALP) activity has been found in both intraradical (Gianinazzi et al 1979, Smith & Gianinazzi-Pearson 1990, Tisserant et al 1993) and extraradical AM fungal mycelium (Boddington & Dodd 1999, van Aarle et al 2001. It is assumed that the ALP of the intraradical mycelium is involved in the transfer of P from the fungus to the plant (Tisserant et al 1993), since a relationship has been found between the ALP of the intraradical mycelium and P transfer (Tisserant, Gianinazzi & Gianinazzi-Pearson 1996).…”

Section: Introductionmentioning

confidence: 99%

Phosphatase activities of arbuscular mycorrhizal intraradical and extraradical mycelium, and their relation to phosphorus availability

Aarle

Rouhier

Saitô

2002

Mycological Research

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We investigated the influence of changes in external phosphorus (P) concentration on the proportion of phosphatase-active structures of the arbuscular mycorrhizal fungus Gigaspora margarita associated with Allium cepa. The P treatment was started when mycorrhizal colonisation had been established, and plant systems were harvested three times after the start of the P treatment. Higher shoot dry weights and P contents were observed in the high-P treated plants at the last harvest. We did not find any change in the proportion of phosphatase-active extraradical mycelium following P treatment. However, the proportion of alkaline phosphatase-active mycelium was positively correlated for extraradical and intraradical mycelium. Also, the proportion of alkaline phosphatase-active arbuscules seemed to increase with the shoot fresh weight, whereas the proportion of acid phosphatase-active arbuscules decreased with higher shoot P concentration and dry weight. We have shown experimentally that the intraradical mycelium of G. margarita, but not the extraradical mycelium, responds metabolically to plant P concentration, and possibly also to external P availability.

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Evidence that differences in phosphate metabolism in mycorrhizas formed by species of Glomus and Gigaspora might be related to their life‐cycle strategies

Cited by 85 publications

References 34 publications

TILLING Mutants of Lotus japonicus Reveal That Nitrogen Assimilation and Fixation Can Occur in the Absence of Nodule-Enhanced Sucrose Synthase

TILLING Mutants of Lotus japonicus Reveal That Nitrogen Assimilation and Fixation Can Occur in the Absence of Nodule-Enhanced Sucrose Synthase

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Phosphatase activities of arbuscular mycorrhizal intraradical and extraradical mycelium, and their relation to phosphorus availability

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