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...ate, phosphonates (Turner et al. 2004), phospholipids, nucleotides, sugar phosphate (Tisdale et al. 1985) phytates, nucleic acids, phosphate ester, and adenosine phosphates (Jayachandran et al. 1992; =-=Marschner 1995-=-). Finally, we grew plants for just 8 weeks; therefore, in this study, we only focussed on the early stages of below-ground competition between D. cespitosa and V. vitis-idaea, and recent evidence sug...

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...ay be more adept at utilizing specific P sources (Turner 2008). The conceptual model outlined by Turner (2008) is a development of ideas based on differential utilization and availability of N forms (=-=McKane et al. 2002-=-) but is so far untested in the context of P utilization. However, there is considerable circumstantial evidence underpinning the ideas described in the ª 2013 The Authors. Ecology and Evolution publi...

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...their reaction on different substrates. Phytase, also known as myo-insitolhexakis phosphate phosphohydrolase, is a phosphatase that hydrolyzes sodium phytate, releasing inorganic free orthophosphate (=-=Wyss et al. 1999-=-). Phytase can be secreted by plant roots (Li et al. 1997), especially when grown in P deficient conditions. Despite the wide range of data available suggesting that partitioning of soil P has potenti...

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...ound in the current experiment might be the different types of mycorrhizal fungi supported by the plants used; V. vitis-idaea forms ericoid mycorrhizas, and D. cespitosa forms arbuscular mycorrhizas (=-=Harley and Harley 1987-=-). The role of arbuscular mycorrhizal fungi in acquiring P via production of extracellular phosphatases is uncertain. One study estimated that utilization of P from phytic acid and subsequent transloc...

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...lants to release organic acids and mobilize P in the rhizosphere, which can have significant positive effects on the growth and nutrition of neighboring co-occurring species without such adaptations (=-=Johnson et al. 2004-=-). We found that the performance (biomass) of plants differed when supplied with a mixture of P forms compared with what would be predicted based on the assumption of equal utilization of P from each ...

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...ich results in precipitation of highly insoluble Fe or Al phosphates, or occlusion of P in Fe or Al complexes. Between 30% and 65%, but sometimes >90%, of the total soil, P is found in organic forms (=-=Harrison 1987-=-) but this pool has traditionally been considered to be unavailable to plants. The forms of P found in soils vary in structure and lability such that their recalcitrance often declines in the order in...

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...sition. Introduction The availability of phosphorus (P) is increasingly recognized as a key nutrient that limits productivity, either on its own or in combination with other mineral nutrients like N (=-=Wassen et al. 2005-=-). In most organic soils, P availability is often considered to be very low because of the acidity of many peat soils, which results in precipitation of highly insoluble Fe or Al phosphates, or occlus...

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...sa roots. Phosphomonoesterase activity was quantified using the substrate p-nitrophenyl phosphate (p-NPP), which breaks down to produce p-nitrophenol (p-NP), which is measured spectrophotometrically (=-=Tabatabai and Bremner 1969-=-). Phytase activity was quantified using the substrate sodium phytate and the enzyme activity measured according to the concentration of PO4 released (Li et al. 1997). The subsamples of fresh roots we...

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...ced virtually no phytase, that may have facilitated access the simple phosphate monoester, DG6P. DG6P is weakly sorbed and considered among the most abundant and available of organic P forms in soil (=-=Condron et al. 2005-=-). These data therefore suggest that P partitioning by these plants is regulated, at least in part, by production of root surface phosphatase enzymes and provides support for our second hypothesis. Th...

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...es for specific components of the heterogeneous soil organic P pool (Turner 2008). The production of phosphatases by Eriophorum vaginatum has been estimated to account for 69% of its annual P demand (=-=Kroehler and Linkins 1988-=-). Plantago lanceolata and Rumex acetosella, both of which are abundant in extensively grazed pastures, differ markedly in their utilization of soil P fractions (Fransson et al. 2003). Similarly, the ...

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... 1996). A further factor leading to P partitioning is the potential of plants to produce different types of P-degrading enzymes. Phosphomonoesterase is active under both alkaline and acid conditions (=-=Criquet et al. 2004-=-), and these enzymes differ in their reaction on different substrates. Phytase, also known as myo-insitolhexakis phosphate phosphohydrolase, is a phosphatase that hydrolyzes sodium phytate, releasing ...

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... the species of plant, thus supporting the idea of resource partitioning for P in soil (Turner 2008). For example, P-degrading enzymes vary considerably between species and functional type of plants (=-=Johnson et al. 1999-=-; Phoenix et al. 2004; Venterink 2011), and it has been suggested that this reflects different affinities for specific components of the heterogeneous soil organic P pool (Turner 2008). The production...

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...ssibly colonization by different species of mycorrhizal fungi, may also promote partitioning of soil P. For example, ectomycorrhizal fungi are able to access phosphate esters and inositol phosphates (=-=Antibus et al. 1992-=-), while ericoid mycorrhizal fungi can efficiently use phosphate diesters (Leake and Miles 1996). A further factor leading to P partitioning is the potential of plants to produce different types of P-...

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...P forms. For example, we now know that the relative proportions of organic forms of P often varies in soil (Turner et al. 2002b), and correlative-based approaches suggest that vegetation composition (=-=Cross and Schlesinger 2001-=-) may affect this. Plants respond to P deficiency in a variety of ways, including changing root morphology, increasing production of extracellular phosphatases, upregulating P transporter genes, and f...

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... as myo-insitolhexakis phosphate phosphohydrolase, is a phosphatase that hydrolyzes sodium phytate, releasing inorganic free orthophosphate (Wyss et al. 1999). Phytase can be secreted by plant roots (=-=Li et al. 1997-=-), especially when grown in P deficient conditions. Despite the wide range of data available suggesting that partitioning of soil P has potential to occur, and the development of a theoretical model b...

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...mycorrhizal fungi can utilize organic P sources by releasing a suite of phosphatases (although thus far phytase has yet to be tested), and could transport P back to host plants (Leake and Miles 1996; =-=Myers and Leake 1996-=-). The plant community found at our study site comprises a number of species with other root adaptations that enable them to acquire P efficiently, notably M. gale (cluster roots) and Carex spp. (dauc...

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...f soil P. For example, ectomycorrhizal fungi are able to access phosphate esters and inositol phosphates (Antibus et al. 1992), while ericoid mycorrhizal fungi can efficiently use phosphate diesters (=-=Leake and Miles 1996-=-). A further factor leading to P partitioning is the potential of plants to produce different types of P-degrading enzymes. Phosphomonoesterase is active under both alkaline and acid conditions (Criqu...

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...lizing enzymes is deposition of atmospheric reactive N, which has been shown to stimulate enzyme activity to different extents depending on species identity (Johnson et al. 1999; Phoenix et al. 2004; =-=Phuyal et al. 2007-=-) and functionality (i.e., whether they are able to fix atmospheric N; Venterink 2011). One further explanation of the contrasting activities of phosphatase enzymes found in the current experiment mig...

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...community found at our study site comprises a number of species with other root adaptations that enable them to acquire P efficiently, notably M. gale (cluster roots) and Carex spp. (dauciform roots; =-=Playsted et al. 2006-=-). However, these adaptations usually are nonspecific in terms of P acquisition. Instead, they enable plants to release organic acids and mobilize P in the rhizosphere, which can have significant posi...

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...rms in peatlands. Secondly, we used only three P forms (plus the mix), which may not represent fully the complex P pool in many ecosystems. In peatland, P storage can range between 0.2 and 0.5 gm2 (=-=Whigham et al. 2002-=-) and comprises numerous organic P forms including inositol phosphate, orthophosphate diester, pyrophosphate, phosphonates (Turner et al. 2004), phospholipids, nucleotides, sugar phosphate (Tisdale et...

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...ng the grass Agrostis capillaris shows that phytate is hydrolyzed and taken up by the plant within hours of exposure to the root systems and thus contributes significantly to its nutritional demands (=-=Macklon et al. 1997-=-). Our understanding of the composition and turnover of organic P in soil has increased markedly, in many cases by application of nuclear magnetic resonance (NMR) imaging, and these advances demonstra...

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..., thus supporting the idea of resource partitioning for P in soil (Turner 2008). For example, P-degrading enzymes vary considerably between species and functional type of plants (Johnson et al. 1999; =-=Phoenix et al. 2004-=-; Venterink 2011), and it has been suggested that this reflects different affinities for specific components of the heterogeneous soil organic P pool (Turner 2008). The production of phosphatases by E...

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... of ester bonds between organic carbon and P (Sahu et al. 2007). There is evidence that certain plants are capable of hydrolyzing organic P compounds in P deficient circumstances (Felipe et al. 1979; =-=Tarafdar and Claassen 2003-=-) but that this may differ according to the species of plant, thus supporting the idea of resource partitioning for P in soil (Turner 2008). For example, P-degrading enzymes vary considerably between ...

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...ase and phytase activity in 0.5 g samples of soil. Measurement of N and P in shoots and soil Samples were digested at 370°C for 4 h in a salicylic acid/ sulfuric acid mix with a CuSO4/LiSO4 catalyst (=-=Bremner and Mulvaney 1982-=-) and diluted with distilled water (1:10). Determination of N and P was undertaken colorimetrically by auto-analysis (TecatorFIAStar 5010; Foss UK Ltd, Didcot, Oxfordshire, UK). Data analysis The effe...

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...anic P by hydrolysis of ester bonds between organic carbon and P (Sahu et al. 2007). There is evidence that certain plants are capable of hydrolyzing organic P compounds in P deficient circumstances (=-=Felipe et al. 1979-=-; Tarafdar and Claassen 2003) but that this may differ according to the species of plant, thus supporting the idea of resource partitioning for P in soil (Turner 2008). For example, P-degrading enzyme...

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...sphate diester, pyrophosphate, phosphonates (Turner et al. 2004), phospholipids, nucleotides, sugar phosphate (Tisdale et al. 1985) phytates, nucleic acids, phosphate ester, and adenosine phosphates (=-=Jayachandran et al. 1992-=-; Marschner 1995). Finally, we grew plants for just 8 weeks; therefore, in this study, we only focussed on the early stages of below-ground competition between D. cespitosa and V. vitis-idaea, and rec...

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...quire more P from soil. Plant roots have a similar capability as many soil microorganisms to secrete phosphatases, which release inorganic P by hydrolysis of ester bonds between organic carbon and P (=-=Sahu et al. 2007-=-). There is evidence that certain plants are capable of hydrolyzing organic P compounds in P deficient circumstances (Felipe et al. 1979; Tarafdar and Claassen 2003) but that this may differ according...

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...t al. 2002) and comprises numerous organic P forms including inositol phosphate, orthophosphate diester, pyrophosphate, phosphonates (Turner et al. 2004), phospholipids, nucleotides, sugar phosphate (=-=Tisdale et al. 1985-=-) phytates, nucleic acids, phosphate ester, and adenosine phosphates (Jayachandran et al. 1992; Marschner 1995). Finally, we grew plants for just 8 weeks; therefore, in this study, we only focussed on...

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...chloroacetic acid (TCA). Protein precipitated by TCA was removed by centrifugation at 10,000 g for 10 min, and the supernatant was analyzed for liberated PO4 using the ascorbic acid/molybdate method (=-=Watanabe and Olsen 1965-=-). After both assays, the fresh weight of all the root samples was determined, and enzyme activity expressed per unit fresh weight. The same procedure was followed for the assay of phosphomonoesterase...