Molecular characterization of an expressed sequence tag representing the cuticle-degrading serine protease gene (PII) from the nematophagous fungus Arthrobotrys oviformis by differential display technology.

The technology of mRNA-based differential display reverse transcriptase-polymerase chain reaction (DDRT-PCR) was used to detect a 246-bp differentially expressed fragment from the nematophagous fungus Arthrobotrys oviformis when young mycelia were induced with the round worm Haemonchus contortus. The fragment was converted into an expressed sequence tag (EST) through characterization at the molecular level. Homology search indicated that the differentially expressed fragment originated from the cuticle-degrading serine protease gene, which has been previously reported to play a role in nematophagous activity in A. oligospora, Dactylaria parvispora, A. musiformis, and other potential anti-fungal biological control agents. Several single nucleotide polymorphisms found to represent both synonymous as well as non-synonymous mutations within this short sequence stretch of 246 bp suggested genetic variability within the gene in this group of nematode-trapping fungi. The cloned EST fragment has potential for use as a hybridization probe for searching full-length gene from an appropriate cDNA library of this and related fungi. This is the first report of the identification of an EST representing the cuticle-degrading serine protease gene from A. oviformis using the technique of DDRT-PCR.