Deposition of nitrogen in vacuolar bodies of Cenococcum geophilum Fr. mycorrhizas as detected by electron energy loss spectroscopy

Abstract

SUMMARYNitrogen fertilization of potted Pinus sylvestris L. seedlings growing in forest humus was carried out using two different concentrations of ainmonium sulphate and ammonium chloride, corresponding to 50 and 100 kg N ha~Ĉ enococcum 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 byphae significantly increased after fertilization witb both atnmonium salts. Tbe bodies were analyzed by electron energy loss speetroscopy. Nitroget-i and phosphorus content increased following ammonium sulphate fertilization, but decreased witb ammonium chloride. Cytoplasmic injury was observed in the byphae in both ammonium chloride treatments but only in tbe higher ammonium sulphate treatment. It is hypothesized that the bodies have a transient storage and N-Hltering function.

Element storage in spores of Gigaspora margarita Becker & Hall measured by electron energy loss spectroscopy (EELS)

“…Carbon was highly detected in these bodies, since it is the main element in the organic compounds of the storage structures. In some of vacuoles and BLO P was also found, however in those bodies where P was not detected, it is not possible to consider them devoid of it, because the detection limit of EELS in biological material is not yet clarified (Kottke et al 1995). Some N and P loss might occur during the preparation of the material (Young et al 1993).…”

“…Electron energy loss spectroscopy (EELS) -The amounts of N, C and P in the spores were measured on sections 40-50nm thick, without further treatment, by using the Electron Energy Loss Spectroscopy (EELS), connected to the TEM, according to the procedures described by Kottke (1991) and Kottke et al (1995). The system was set as follows: Spectra were acquired at a magnification of 50,000.…”

“…However, the absolute amount of the elemnts cannot be calculated once that standards for EELS are not available (Kottke et al 1995). In the case specific for C the results were subtracted from those found in the pure Epon. As mentioned by Kottke et al (1995), the relative concentrations of the elements were influenced by the section thickness. The data were statistically analyzed and the standard deviation calculated by Excel program.…”

“…However, the need to embed the material might cause a risk to lose substances and cells with damaged membranes are more susceptible to be reached. Kottke et al (1995) demonstrated the sequestration of N and P in osmophilic bodies in the hyphal mantle of Cenococum geophilum Fr. mycorrhizas as detected by EELS.…”

Nitrogen deposition and ectomycorrhizas

“…However, even at the lowest N application rate, osmiophilic vacuolar bodies were present in the fungal tissue, especially in the mantle. Recently, Kottke et al (1995) demonstrated the sequestration of N and P in these vacuolar bodies in Pinus sylvestris\Cenococcum geophilum mycorrhizas. Fertilization with both NH % Cl or (NH % ) # SO % with 50 or 100 kg N ha −" during the 9-wk growth period increased the number of osmiophilic vacuolar bodies.…”