No description available.

No description available.

No description available.

No description available.

No description available.

The fine structure of the basidiospores of Pluteus cervinus and Agrocybe acericola is described using TEM, SEM, and light microscopy.The basidiospore wall of Pluteus cervinus is bipartite. No surface ornamentation or germ pore is present. The protoplasm is surrounded by a typical membrane which lacks distinct invaginations. Spores contain much stored lipid, which is centrally located. Spores are uninucleated with the nucleus closely appressed to the cell membrane, located at the base of the spore near the hilar appendage. Mitochondria with few, well-delineated plate-like cristae are present. Endoplasmic reticulum (ER) is scant. Ribosomes occur regularly attached to the ER and outer mitochondrial membrane, as well as being densely packed throughout the cytoplasm. Various sized vacuoles containing an electron dense material are present. Microbody-like organelles are observed, which are probably glyoxysomes, since assays of malate synthase, a maker enzyme of the glyoxylate cycle, are positive.The basidiospore wall of Agrocybe acericola is composed of two distinct layers, both layers are continuous around the spores, at the germ pore the outer wall is very thin and the inner wall becomes thicker. The plasma membrane is appressed to inner wall and lacks invaginations. The protoplasm is densely packed with small granules, probably ribosomes and/or glycogen. Spores contain very little lipid with bipolar distribution. Mitochondria are well-defined and distributed in cytoplasm. Spores are binucleate with the two nuclei lying on a line nearly perpendicular to the long axis of the cell. Various size single membrane-bound vacuoles are widely distributed in the cytoplasm. These vacuoles were shown to contain acid phosphatase indicating lysosomal activity. Microbodies, probably glyoxysomes, are observed. Malate synthase assays are positive indicating the occurrence of the glyoxylate cycle. / Department of Biology

No description available.

Shoot dieback of lodgepole pine in the British Isles has been a long standing problem, but it was not known whether or not a pathogen was involved. During 1980--1982, a shoot dieback disease of lodgepole, similar to those previously observed at different places, was studied at the Glengarry and Eilanreach forests in the northwest of Scotland. Dieback symptoms and stages in their development were investigated. A thorough review of the literature on dieback disease of lodgepole pine indicated that different disease symptoms were involved in the present outbreaks. A hitherto undescribed fungus, Ramichloridium pini de Hoog & Rahman was found to be closely associated with the early stages of discolouration of the buds and shoots of lodgepole pine while Sclerophoma pythiophila (Cda.) Hohn was most prevalent on healthy and dead tissues. A new modified Czapek Dox Agar medium has been found to suppress S. pythiophila significantly while allowing normal growth of R. pini at about 15°C, which is the optimum temperature for the latter. A method of mass production of inoculum was devised. For germination of the conidia of R. pini free water is not essential. Good germination of conidia and elongation of germ tubes occurred on undetached flushing needle sheaths and bud scales. Extensive artificial inoculations have firmly established that R. pini is the primary pathogen of the present shoot dieback disease of lodgepole pine. Most successful infections were obtained from inoculations carried out in May and June. By October, shoots became resistant to infection. Plants of the Central Nass River provenance were more resistant to R. pini than those from Long Beach, Washington. It has been shown that conidia produced on needle fascicle scars could provide natural inoculum. The infection period lay between mid April to mid May or up to early June at Eilanreach in 1981.

Since many approaches to dealing with algal blooms are inefficient, expensive, or harmful, it was concluded that a biologically-synthesized chemical agent, specifically inhibitory to pre-bloom algal cells, might prove helpful in controlling algal blooms. Fungi were chosen as the biological entities to investigate for such a chemical.

The nature and occurrence of mycorrhizal associations, with particular reference to the anatomy, carbohydrate physiology, plant mineral nutrition and occurrence of ectomycorrhizae (ECM), is discussed. The ecology and forest relations of <i>Picea sitchensis</i> - the Sitka spruce concludes the literature review. Identification of areas of good and poor Sitka growth on related soils and the quantification of their ECM status, investigation of the effect of phosphate addition to Sitka seedlings in pots, subsequent and changes to their ECM status, and the effects of soluble aluminium on phosphate nutrition of Sitka seedlings, the collation of results and relation back to the field situation were carried out as experimental work. Field sites were identified and described in terms of geology, soils, field ECM status, forest productivity and nutrient status. Three pot experiments were carried out. The 1st investigated the effects of phosphate application on ECM Sitka seedlings in soil from the field sites; the 2nd investigated the effects of phosphate application to ECM and non-mycorrhizal (NM) seedlings in compost; and the 3rd investigated the affects of application of Al-citrate to ECM and NM seedlings in compost containing high and low levels of phosphate. The results obtained were described and discussed in the context of a model of the factors affecting plant response to the soil environment. The field ECM development representing a considerable drain on the carbohydrate economy of the field sites was to some extent duplicated in the greenhouse. The possible decrease in importance of this drain was illustrated by phosphate application, but was increased by addition of Al-citrate. A previously unrecorded ECM-enhanced uptake of Manganese was reported. The importance of phosphate in the soils under discussion was emphasised, and possible further work suggested.