Article

A set of enzymes involved in various metabolic pathways in Botrytis cinerea and Septoria nodorum, two important necrotrophic plant pathogens, was studied cytochemically. Mycelia growing in ovaries of Lilium regale and seeds of Triticum aestivum, respectively, showed high activity of some hydrolases (a-esterase, AS-D-esterase, acid phosphatase, ~-glucosidase, a-galactosidase), 10caIized in cytoplasmic granules. Acid phosphatase was observed outside of the hyphae of S. nodorum, and A TPase within. Hydrolytic enzymes probably contribute both to the penetration of host cells and the utilization of their nutrient substances. The citric acid cycle and glycolysis occur in both fungi, as revealed by the presence of the dehydrogenases studied. S. nodorum has 6-phosphogluconate dehydrogenase, involved in the pentose phosphate pathway, whereas B. cinerea is characterized by the presence of peroxidase and polyphenoloxidase; the latter, which is probably related to cross-linking of matrix polymers in the celi wall, is also found in senescent hyphae of S. nodorum.