Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 26, 1999
Publication Date: N/A
Interpretive Summary: The filamentous fungus Paecilomyces fumosoroseus is a common insect pathogen and soilborne organism that has been isolated from a wide variety of insects from different orders located throughout the world. This organism can induce natural infections of insects and has been registered as a microbiological control agent. We are interested in how this fungus interacts and develops within two of its insect hosts, the diamondback moth and the Russian wheat aphid, as a means to understand and improve the biological control capacity of this organism. Using genetic transformation techniques developed in our laboratory, we introduced a gene into the genome of P. fumosoroseus that causes individual cells of the fungus to fluoresce. With this marker we are able to follow easily the progress of the fungus during infection without additional processing of insect or fungus tissues. This new tool will enable us to identify more readily those fungal traits that enhance the abilities of this insect pathogen.
The green fluorescent protein (GFP) from the jellyfish Aequorea victoria has been expressed in a variety of prokaryotic and eukaryotic organisms and has been used extensively as a marker in the study of host-pathogen interactions. We have expressed GFP in the entomopathogenic fungus Paecilomyces fumosoroseus through co-transformation with a vector that confers resistance to glufosinate ammonium. All cell types express GFP and were readily detected by fluorescence microscopy. No correlation was observed between the amount of fluorescence and the pattern of vector integration as observed by Southern analysis. Fluorescent hyphae and conidia were easily distinguished on two insect hosts, the Russian wheat aphid Diuraphis noxia and the diamondback moth Plutella xylostella, and blastospores were also detected in the hemolymph of the diamond back moth. GFP-tagged strains P. fumosoroseus can be used to study the developmental fate of the fungus within its insect hosts.