The effects of virus disease upon certain aspects of the nitrogen metabolism of the cultivated mushroom Agaricus bisporus (Lange) Sing, were of host metabolism. The significance of these observations is discussed. Relationship shown by diseased cultures of vegetative mycelium on agar were studied in particular. Disturbances of sporophore metabolism which could be used for diagnostic techniques were also sought. Healthy myceilal cultures and two diseased cultures of different growth rates were isolated from sporophores and used as inoculums for submerged culture. Growth of the various isolates in submerged culture was studied in detail. Rates of protein synthesis and of uptake of the amino acids glycine and proline were measured by the use of radioactive isotopes; qualitative aspects of protein metabolism were studied by polyacrylamide gel electrophoresis. Glycine uptake by healthy mycelium was found to vary with the age of the mycelium, to be affected by pH and metabolic poisons and to show saturation kinetics. Diseased cells showed reduced rates of protein responsible for the observed reductions in uptake is presented. Protein patterns and isoenzymes of diseased mycelium were different to those of healthy. A special feature established by this study was that cultures of intermediate growth rate also showed intermediate degrees of disturbance of host metabolism. The significance of these observations is discussed. Diseased mycelium was rendered non-infectious by heat treatment; such treated cultures resembled normal healthy mycelium in every respect. Isoenzyme patterns of healthy sporophores were studied by disc electrophoresis and found to be very reproducible; diseased tissue gave different enzymes. The use of disc electrophoresis as a diagnostic tool for mushroom virus disease is indicated. An increase in O-diphenoloxidase activity in extracts from diseased mushrooms was also found.
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