Self-germination inhibitors fromColletotrichum fragariae.

The conidial germination ofColletotrichum fragariae in water was dependent on population, size germination was inhibited at higher concentrations of conidia in water. The inhibition was considered to be caused by some germination-inhibiting substances exuded from conidia, since the germination did occur after washing the conidia repeatedly. The germination-inhibiting substances were searched for in the acetone extract of potato-sucrose-agar (PSA) cultures of the fungus and five active compounds were isolated. Their structures were characterized spectroscopically. HPLC analysis indicated that one of the isolated compounds among these was exuded not only from mycelia but also from the conidia in water under crowded conditions. We suggest that these compounds control the conidial germination of the fungi.