Extracellular enzymes of Chondrostereum purpureum , causal fungus of silverleaf disease

Chondrostereum purpureum, the casual fungus of silverleaf disease, was grown on solid media supplemented with a range of oligosaccaride carbon sources. Extracellular extracts were analysed for a range of wooddegrading enzymes. The results indicate that C. purpureum is a highly specialised plant pathogen which does not produce lignin degrading enzymes. Cellulose substrates produced slow growth of the fungus, but induced large amounts of enzymes able to degrade celluloses, xyloglucans and pectins. Growth on Link pectin and pectin was rapid, with the induction of enzymes able to degrade pectins and cellulases. The growth data suggests that the cellulases especially, but also pectinases, play a key role in xylem invasion rather than in nutrition. The fungus also has the capacity to utilise protein and starch. The results are discussed in relation to the local and systemic effects of the fungus.

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