DEPOSITION OF NITROGEN IN VACUOLAR BODIES OF CENOCOCCUM-GEOPHILUM FR MYCORRHIZAS AS DETECTED BY ELECTRON-ENERGY-LOSS SPECTROSCOPY

Nitrogen fertilization of potted Pinus sylvestris L. seedlings growing in forest humus was carried out using two different concentrations of ammonium sulphate and ammonium chloride, corresponding to 50 and 100 kg N ha-1. Cenococcum geophilum Fr. mycorrhizas were collected from the root systems of the seedlings and investigated by light and transmission electron microscopy. The number of vacuolar osmophilic bodies in the mantle hyphae significantly increased after fertilization with both ammonium salts. The bodies were analyzed by electron energy loss spectroscopy. Nitrogen and phosphorus content increased following ammonium sulphate fertilization, but decreased with ammonium chloride. Cytoplasmic injury was observed in the hyphae in both ammonium chloride treatments but only in the higher ammonium sulphate treatment. It is hypothesized that the bodies have a transient storage and N-filtering function.