Cytological Characterization of Anamorphic Fungus Lecanicillium pui and Its Relationship with Chinese Caterpillar Mushroom, Ophiocordyceps sinensis (Ascomycetes)

Ophiocordyceps sinensis (syn. Cordyceps sinensis), one of the most valuable medicinal mushrooms, has great economic importance on the Tibetan Plateau. We isolated an anamorphic fungus Lecanicillium pui from natural O. sinensis specimens and found that the optimal temperature for its culture on potato dextrose agar media was 25°C. Cell ultrastructure in L. pui hyphae and spores was characterized by transmission electron microscopy, and it was observed that some primary organelles showed the typical fungal features. Five chemical elements were determined in this fungus and niobium was discovered for the first time even with trace amounts. A species-specific method, nested polymerase chain reaction, was established to investigate the colonization of this fungus. Thus, the extensive distribution of L. pui on O. sinensis, in the shape of hyphae or mycelia, suggested that it may have subtle and chronic effects on the growth of the O. sinensis teleomorphic stage. These findings provide a potential reference, in the view of microbial ecology, for the study on the occurrence and mechanism of development of O. sinensis.