Induction of basidiospore germination by gluconic acid in the ectomycorrhizal fungus Tricholoma robustum

Abstract

Basidiospore germination in the ectomycorrhizal fungus Tricholoma robustum and related species Tricholoma matsutake, Tricholoma caligatum, and Tricholoma ponderosum was examined. Basidiospore germination in T. robustum was induced by the presence of conspecific mycelium but not by the mycelium of related species. Germination also occurred on conditioned medium prepared by preculturing with conspecific mycelium. Gluconic acid, which is produced by T. robustum, also induced basidiospore germination in that species. After storage at 5 °C, germination of basidiospores in T. robustum was stimulated by incubation with conspecific mycelium but not with gluconic acid. These findings suggest that gluconic acid is but one of perhaps many germination-inducing substances produced by the mycelium of T. robustum. Key words: basidiospore germination, ectomycorrhizal fungi, gluconic acid, mycelial culture, Tricholoma robustum.