X-Ray Microanalysis of Elements in Cells of Va Mycorrhizal and Nonmycorrhizal Onions

Elemental composition in vesicles of an arbuscular mycorrhizal fungus, as revealed by PIXE analysis

“…P is stored mainly as polyphosphate in the vesicles, and both polyphosphate (Kornberg et al 1999) and Cl (Wada et al 1992) contribute to acidification in cells and this could thus be a reason for the negative correlation between these two elements. Similarly, Schoknecht & Hattingh (1976) found that arbuscules contained high amounts of P, but no detectable Cl, while nonmycorrhizal cells contained no P and relatively much Cl. Plants treated with high amounts of NaCl had reduced content of P in the roots (Allen & Cunningham 1983), but from that particular study it can not be concluded if this was due to interaction with mycorrhizal uptake of Cl.…”

“…Plants usually have 0.2 % P (Salisbury & Ross 1985;Marschner 1995), while we found between 0.4 and 0.7 % P in the vesicles. Plant cells with mycorrhizal structures are known to contain higher P levels than other parts of the root (Schoknecht & Hattingh 1976;Weiersbye et al 1999). Rasmussen et al (2000) showed that cucumber roots colonised by the AM fungus Glomus intraradices contained polyphosphate while nonmycorrhizal roots did not.…”

Formation of Metachromatic Granules Following Phosphate Uptake by Mycelial Hyphae of an Ectomycorrhizal Fungus

“…Several authors have reported that considerable quantities of calcium are consistently associated with the phosphate in mycorrhizal granules (Schoknecht & Hattingh, 1976;White & Brown, 1979;Strullu et al, 1981aStrullu et al, , 1982 and the suggestion has been made (Strullu et al, 1981a) that the calcium might be necessary to balance the negative charge of the polyphosphate polyanions. For this reason, particular attention was paid in the present study to granule formation in the presence and absence of calcium, and within two different strains of P. involutus -one ecologically calcicole and the other calcifuge.…”

“…Although these mycorrhizal and lichen granules have not yet been successfully isolated for analysis, the red metachromasy, together with other histochemical reactions and tests, provides strong evidence that they contam substantial quantities of polyphosphate . In addition, electron-dense granules from endo-and ectomycorrhizas, which appear to equate with the metachromatic granules, have been detected ultra-microscopically and shown by electron-probe analysis to contain high concentrations of phosphate, together with Ca, Mg, K and traces of other elements (Schoknecht & Hattingh, 1976;White & Brown, 1979;Strullu, Gourret & Garrec, 1981a;Strullu et al, 1981 b;. Further indirect evidence that the metachromatic granules respresent an accumulation of phosphorus is provided by studies in which fungal sheath tissue of beech ectomycorrhizas has been incubated in phosphate solutions under various conditions and revealed strong correlations between uptake of radiophosphorus (Harley & McCready, 1952) and increase in number and size of metachromatic granules (Chilvers & Harley, 1980).…”

A Phosphate Transporter from Medicago truncatula Involved in the Acquisition of Phosphate Released by Arbuscular Mycorrhizal Fungi

“…Thus, the coordinated differentiation of both symbionts is required to achieve arbuscule formation, and analyses of the cytoskeleton of the invaded cells indicate extensive, dynamic rearrangements of the cortical microtubules, which presumably enables the trafficking of membrane and cell wall precursors to the extending membrane and new apoplastic compartment (Genre and Bonfante, 1997Blancaflor et al, 2001). The plant plasma membrane extends ‫ف‬ 10-fold to surround the arbuscule (Alexander et al, 1989), and this extensive interface, coupled with the high phosphate content of these cells (Cox and Tinker, 1976;Schoknecht and Hattingh, 1976;Cox et al, 1980), supports the suggestion that phosphate transport between the fungus and the plant occurs at this location.…”