ULTRASTRUCTURE AND ELECTRON‐PROBE MICROANALYSIS OF THE METACHROMATIC VACUOLAR GRANULES OCCURRING IN TAXUS MYCORRHIZAS

Abstract

SUMMARYNumerous metachromatic vacuolar granules occur in the hyphae of the fungal symbiont of Taxus baccata mycorrhizas. These granules exist in the trunks and in proliferating arbuscules but they are absent in lysed arbuscules. Direct microanalysis with an electron probe shows that they have a high phosphorus and calcium content. Potassium and magnesium are also present but in lesser quantities. The concentration of phosphorus and calcium is higher in the granules than in the light part of the vacuoles. The concentration of phosphorus also is higher in the granules than in the nuclei of the root, cells and the concentrations of calcium are greater than those measured in the pecto-cellulosic wall of root cells. The role of calcium in the metabolism of phosphorus within the tissues of mycorrhizas still remains unknown.

Identification of Genes Differentially Expressed in Extraradical Mycelium and Ectomycorrhizal Roots during Paxillus involutus-Betula pendula Ectomycorrhizal Symbiosis

“…This view is consistent with the observed translocation patterns of phosphorus through ectomycorrhizal mycelia in association with pine seedlings (53). Polyphosphates were detected in fungal vacuoles of ectomycorrhizae (8,51), and Arg and Gln were proposed to be the associated cations to neutralize them (51). Through vacuole exchange, these N compounds, in particular, Arg, could be translocated from extraradical to intraradical mycelium, as already described for endomycorrhizal and ectomycorrhizal systems (3).…”

CHARACTERIZATION OF THE DIFFERENT FORMS OF PHOSPHORUS IN THE MYCELIUM OF THE ECTOMYCORRHIZAL FUNGUS, HEBELOMA CYLINDROSPORUM, CULTIVATED IN PURE CULTURE

“…Rapid phosphate translocation in VA mycorrhizal fungi could be explained by cytoplasmic streaming mechanisms (Tinker, 1975) and the possible synthesis and degradation of polyphosphate (Cappacio & Callow, 1982). Polyphosphate granules disappear in the arbuscules (Strullu et al, 1980), which suggests that they are degraded to orthophosphate. This orthophosphate seems to be actively transported across the host plasmalemma and to be associated with ATPase activities occurring in infected host cells (Marx et al, 1982).…”

“…Very little is known about the processes involved in the transport of phosphorus from fungus to the host. Accumulation and translocation of significant amounts of phosphorus by hyphae of vesicular arbuscular (VA) mycorrhizal fungi seem to occur via polyphosphate condensed in the vacuole (Cox et al, 1975;White & Brown 1979;Strullu et al, 1980). Rapid phosphate translocation in VA mycorrhizal fungi could be explained by cytoplasmic streaming mechanisms (Tinker, 1975) and the possible synthesis and degradation of polyphosphate (Cappacio & Callow, 1982).…”

Anatomy of a vesicular—arbuscular endomycorrhizal symbiosis between sugar maple (Acer saccharum Marsh) and Glomus etunicatum Becker & Gerdemann

“…Ultrastructural investigations have been performed on a limited number of plant species and an even smaller number of tree species (Fantana, 1985;Frankland & Harrison, 1985;Kinden & Brown, \975a-c;Strullu et al, 1981). Sugar maple {Acer saccharujn Marsh.)…”