In vitro growth of the entomopathogenic hyphomycete Nomuraea rileyi

Abstract

The entomopathogen Nomuraea rileyi is a dimorphic hyphomycete having invasive hyphal stages and a yeastlike vegetative stage. Each phenotype has unique characteristics that contribute to pathogenicity of the fungus towards insects. Growth both in vivo and in vitro is highly synchronous. In vitro, conidial germ tubes produce hyphal bodies (yeastlike cells) in complex mycological medium and, if transferred to a less complex medium (Vogel's), the hyphal bodies synchronously convert to mycelia. This transition can be reversed by transferring the mycelia back to the original medium. The hyphal body phase can be by-passed by placing germ tubes directly into Vogel's. The ability to regulate fungal development provides a means of comparing characteristics (e.g., cell surface epitopes, enzyme production) which differ according to phenotype, and to identify genes associated with phase transitions.

Key Words:

• dimorphism
• morphogenesis
• mycological media