Piriformospora indica, gen. et sp. nov., a New Root-Colonizing Fungus

A new fungus isolate was discovered in an arbuscular mycorrhizal fungal spore from a desert soil in India. It could easily be cultivated on various synthetic media, and formed pear-shaped chlamydospores. Inoculation of maize showed that the fungus colonized the root cortex. Since it did not resemble any known fungus based on morphology and ultrastructure, a new genus was described. For its characteristic spore structure the isolate was named Piriformospora indica. Electron microscopy revealed the presence of typical dolipores with continuous parenthesomes, which indicated that P. indica belongs to the Hymenomycetes (Basidiomycota). DNA was extracted and the 5′ end of the 18S rRNA was amplified and sequenced. Comparison with sequences from the Genbank data base indicated that P. indica is related to the Rhizoctonia group.