Equipment and facilities on the transmission electron microscope

The TEM902 Zeiss (80 kV) has been equipped with an imaging spectrometer of the prism-mirror-prism type and a slit system to separate and select the energy loss electrons desired for microanalysis (Fig. 2). For centring the deflected electrons with an energy of E E0 AE on the optical axis, the accelerating voltage Uq is increased specifically by Fig. 2. Imaging and spectrometer system of the TEM902 ZEISS (after Bauer, Fig. 2. Imaging and spectrometer system of the TEM902 ZEISS (after Bauer, Fig....

Nitrogen utilization

Most ectomycorrhizal fungi are able to utilize both inorganic and organic nitrogen sources. Growth rates and final biomass production give an overall estimate of the fungal efficiency in assimilating a given nitrogen source. The disappearance of nutrients from the growth media as a function of growth rate ( ) has been used for estimating the long-term uptake of compounds in microbial cultures. The most conventional way of measuring nutrient uptake by micro-organisms is by determining the...

Conclusions

Rhizomorphs of wood-rotting fungi are mostly robust and easy to handle, but not always so. However rhizomorphs of mycorrhiza are both fragile and not necessarily susceptible to a varied experimental attack. Read and his colleagues (as exemplified by Finlay and Read, 1986b) have demonstrated very elegantly that mycorrhizal rhizomorphs can link mycelium on separate plants thus the rhizomorphs can channel nutrients, particularly combined carbon, from one plant to another, as well as both exploring...

Naming of unidentified ectomycorrhiza

As has been previously reported, unidentified ectomycorrhiza require binary names in the same way as do fruit bodies of fungi (Gronbach and Agerer, 1986 Agerer, 1987-1990 Weiss and Agerer, 1988), but only when they are described comprehensively and in detail. The name is made up of the genus name of the host tree and a characterizing epithet, for example Piceirhiza gelatinosa (Gronbach and Agerer, 1986) or Laricirhiza alpina (Treu, 1990a). Those names identify an ectomycor-rhiza of the genus...

The general features of mycorrhizal symbiosis

In the majority of mycorrhizal symbioses, the higher plant host is capable of active photosynthesis. In relatively few, such as in the so-called saprophytic plants and in the early growth of orchids and other * The term host is used in this essay, as it so often is, as synonymous with photobiont where the host is a green plant. The characteristics of the important kinds of mycorrhiza. The structural characters given relate to the mature state, not the developing or senescent states. Entries in...

Introduction

Studies of ectomycorrhiza can contribute to elucidation of fungal relationships (Agerer et al., 1990 Agerer, 1991a). Ectomycorrhiza structures consist of fungal tissues, the arrangement and organization of which can be used to describe fungal species in the same way as any other taxonomically suitable feature. Their characteristics are well conserved (Agerer et al., 1990). As ectomycorrhiza formed by different fungi are structurally distinct (Frank, 1885 Chilvers, 1968 Voiry, 1981 Agerer,...

Presentation of results

It is often necessary to examine data in different ways to understand fully the effects of ectomycorrhizal treatments. Sometimes standard statistical procedures on selected parameters (i.e. height, DBH, tree weight, tree volume, etc.) show no significant differences between treatments. Novel approaches for examining data have been employed to provide important information on effects of ectomycorrhizal treatments. For example, in a recent paper evaluating 8-year field performance of loblolly...

The carbon balance of mycorrhiza

Due to the carbon drain by the mycobiont, the pattern of carbon partitioning differs between mycorrhizal and non-mycorrhizal plants. It is of considerable interest to study and quantify the carbon flow to the fungus in relation to the carbon balance of the host and in relation to the influence of mycorrhiza on nutrient acquisition. Sometimes mycorrhiza result in growth depressions such events may be predicted only on the basis of a thorough understanding of the carbon balance of the symbiotic...

Mechanism of nutritional benefit by mycorrhiza

It was long suspected that the very visible benefit given to plants by mycorrhizal infection was due to the supply of additional mineral nutrients. To prove this, it was necessary to show that the fungus could absorb mineral nutrients from the growth medium, transport them through its hyphae, and transfer them to the higher plant. The more general approach was also to prove that the mycorrhizal root system was more efficient than the non-mycorrhizal one. i.e. in the same soil it absorbed...

Enzyme characterization and assay procedures

Nitrate reductase (NR) is a labile enzyme and for this reason a number of protectants are added to the extraction media (Wray and Fido, 1990). These protectants usually include nitrate, which is an NR substrate FAD, which is a prosthetic group present in the protease-sensitive region of NR EDTA, which chelates toxic metals released during cell breakage and sulphydryl compounds such as dithiothreitol and mercap-toethanol, which prevent the oxidation of essential SH-groups of NR. Protease...

Experiments with Ericoid Mycorrhiza

Department of Animal and Plant Sciences, University of Sheffield, Sheffield, B. Other fungi isolated from ericoid mycorrhizal roots 440 C. Other fungi associated with ericaceous roots 441 IV. Aseptic culture of seedlings 442 VI. The role of mycorrhiza in the nutrition of plants with VII. The extent of dependence of the heterotrophic partner upon VIII. Screening of putative mycorrhizal isolates using an assay based upon nutrient release to the host 448 IX. Detoxification of the soil environment...

Morphological characterization colour photography and autofluorescence

Morphological characterization should always be carried out on freshly isolated material, using lamps of daylight quality and a black background (see Section II.C). The checklist and comments given in the Colour Atlas of Ectomycorrhizae (Agerer, 1987-1990) can be used as a guideline. The best record of colours is achieved by taking photographs. Although colour charts are used for descriptions of fungi and have also been used for ectomycorrhiza (Ingleby et al., 1990), for comparative purposes it...

Nuclear magnetic resonance spectroscopy

Nuclear magnetic resonance NMR spectroscopy is a spectroscopic technique that exploits the magnetic properties of the atomic nucleus. The physics and biophysics of NMR have been elucidated for the physiologist by several authors Gadian and Radda, 1981 . Briefly, NMR is a form of spectroscopy based on the properties of nuclides that possess a non-zero spin and associated magnetic moment so that a resonance occurs at a characteristic frequency. The nuclides that are detectable in an NMR...

Chromatographic methods

Ion-exchange is the separation of proteins on the basis of their charge. Proteins carry both positively and negatively charged groups on their surfaces, due largely to the presence of side chains of acidic and basic amino acids. The net charge on a protein depends on the relative numbers of positively and negatively charged groups this varies with pH. The pH at which a protein has an equal number of positive and negative groups is termed its isoelectric point pHi . A wide variety of matrices...

Embedding roots for light microscopy

Excellent results of embedding ectomycorrhiza for light and electron microscopy can be obtained by using LR White, a resin introduced by the London Resin Co. Ltd, Basingstoke, Hampshire, England. This resin works extremely well with ectomycorrhiza because of its very low viscosity, thus achieving good infiltration of both symbionts. In addition, because the cured resin is hydrophilic, most histochemical procedures can be used. A protocol that has been used routinely in my laboratory for light...

Establishment of a collection of mycorrhizal fungi

When starting a collection of ectomycorrhizal fungi it is desirable to obtain cultures from well-known collections or from other ectomycor-rhiza research workers. Cultures are in most cases obtained as agar slants which can be easily sent by post or carried on the person. In cold climates special care must be taken to ensure that mycorrhizal cultures are not frozen during transport. The isolation and cultivation of ectomycorrhizal fungi is greatly facilitated by the use of a laminar...

Erlenmeyer flasks

Leonard Jar Assembly

Some of the first attempts at synthesizing ectomycorrhiza under sterile conditions were made by Melin 1921, 1922 using Erlenmeyer flasks with sand as a substrate for addition of nutrient solution and for root growth. Subsequently, Hacskaylo 1953 used vermiculite while Marx and Zak 1965 used finely ground peat moss mixed with vermiculite in a ratio of 1 15 as the substrate. The substrates provided better aeration for the root system and the addition of peat lowered the pH. Chakra-varty and...

Screening of putative mycorrhizal isolates using an assay based upon nutrient release to the host plant

As indicated earlier, claims, based upon the detection of hyphal complexes in epidermal cells of hair-roots, that a number of fungi other than H. ericae are mycorrhizal with ericaceous hosts, have not so far been verified by demonstration that infection by the re-introduced fungus is followed by nutritional or growth response. There is thus an urgent need for an ecologically meaningful screening procedure which facilitates the analysis of growth or nutritional responses of host plants in the...

Emanating hyphae and cystidia

Emanating Hyphae

As in the case of the hyphae in rhizomorphs, the hyphae emanating from the sheath can also form anastomoses. Several kinds of hyphal connections can be found Fig. 12 . Neighbouring hyphae can either be connected by rather long hyphal bridges Fig. 12D-F or the anastomosis can be very short Fig. 12A-C . They can be open Fig. 12A,D , closed by simple septa Fig. 12B,E or by clamps Fig. 12C,F . Formation B is called a contact-septum, formation C a contact-clamp. Contact clamps are characteristic of...

Ericoid mycorrhizal infection and metal toxicity

As with organic acids, the potential for metallic ions to exert toxic effects is greater at low soil pH, in their case because of increased solubility under acid conditions. It has been shown previously that ericoid infection can confer resistance to copper and zinc toxicity by reducing inflow of the metals to the shoots Bradley et al., 1981, 1982 . Of greater importance as potential toxins in natural environments are the metals aluminium and iron. The inherent toxicity of the former element...