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

Abstract

SUMMARYAbundant metachromatic granules, presumed to contain polyphosphate, were present in mycelial hyphae oiPaxillus involutus (Batsch. ex Fr.) Fr. grown in phosphate-rich medium, but were absent when the medium lacked phosphate. Phosphorus-starved hyphae placed into phosphate-containing solutions developed granules within 3 to 4 h. Most of this period was required for synthesis of granule materials, since phosphate uptake occurred within minutes. Both phosphate uptake and granule formation are active processes, affected by low temperature and respiratory inhibitiors. No special importance seemed to attach to the presence of any of the following cations: Ca2+; Mg^+i K+; or Na+; and two different isolates of P. involutus, one calcifuge and one calcicole, showed no differential effects regarding granule formation in the presence and absence of Ca^+ and K ey words: Ectomycorrhizal fungus, metachromatic granule, polyphosphate, phosphate uptake, calcium.

Aluminium polyphosphate complexes in the mycorrhizal basidiomycete Laccaria bicolor: A 27Al-nuclear magnetic resonance study

“…Forest soils are characterized by a low Pi concentration in solution (1 10 ~tM) and it appears unlikely that the extramatrical mycelium permeating the soil could accumulate Al-PolyP complexes at this concentration. In contrast to this contention, significant amounts of PolyP are present in the ectomycorrhizal mycelium grown on 5 pM Pi (Lapeyrie et al 1984) and in mycorrhizal roots of Pinus resinosa grown under P-limiting conditions (McFall et al 1992). This supports a role for PolyP in binding A1 at the point of uptake.…”

The ability of 16 ectomycorrhizal fungi to increase growth and phosphorus uptake of Eucalyptus globulus Labill. and E. diversicolor F. Muell.

“…Some fungi increased the relative amount of phosphorus in the fine roots compared with the course roots. This is generally attributed to storage of P in mycorrhizas as polyphosphate (Lapeyrie et al, 1984;Mulligan and Patrick, 1985;martin et al, 1985). However, only L. laccata (LAC2) and S. verrucosum on E. globulus increased the relative amount of phosphorus in roots compared with shoots.…”

Aluminium polyphosphate in the ectomycorrhizal fungus Suillus variegatus (Fr.) O. Kunze as revealed by energy dispersive spectrometry

“…Ectomycorrhizas are known to form polyphosphate granules, as revealed by cytochemical tests (Ashford, Ling-Lee & Chilvers, 1975;Lapeyrie, Chilvers & Douglass, 1984) and by energy dispersive X-ray microanalysis (Strullu et al, 1982(Strullu et al, , 1983Ashford et al, 1986). Phosphorus-rich granules have also been demonstrated in VA mycorrhizas (White & Brown, 1979;Cox et al, 1980;Strullu et al, 1981), and it is thought that these may be transported across the fungal sheath into the host (Harley & Smith, 1983).…”