Differentiation of polyphosphate metabolism between the extra- and intraradical hyphae of arbuscular mycorrhizal fungi
2001
Ezawa, T. | Smith, S. | Smith, F.
• Regulation of polyphosphate metabolism is reported in arbuscular mycorrhizal symbiosis. • Marigold (Tagetes patula) plants inoculated with Glomus coronatum or Glomus etunicatum were grown in mesh bags. Exopolyphosphatase activity in extra- and intraradical hyphae was measured and characterized. The hyphae were stained with Neutral red to show acidic vacuoles in which polyphosphate synthesis might occur. • Exopolyphosphate activity was differently expressed between the extra- and intraradical hyphae, as indicated by different pH optima; high activity was observed at pH 5.0 in the intraradical hyphae of both fungal species. K<sub>m</sub> values were lower at neutral pH with long-chain polyphosphate, whereas acidic activity showed lower K<sub>m</sub> with short-chain polyphosphate. Both extra- and intradical hyphae had acidic vacuoles. Polyphosphate occurred in the hyphae of the high-P, but not the low-P treatment. By contrast, exopolyphosphatase activity and vacuolar acidity were relatively constant irrespective of polyphosphate status. • The fungi have at least two different exopolyphosphatase-type enzymes which are differently expressed between extra- and intraradical hyphae; polyphosphate accumulation might be a dynamic balance between synthesis and hydrolysis.
Afficher plus [+] Moins [-]Tatsuhiro, Ezawa; Sally E., Smith; F., Andrew Smith
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