Cloning and characterisation of the gallerimycin gene from immunised Spodoptera litura.

We report the cloning of Sl-gallerimycin from the armyworm Spodoptera litura (F.) (Lepidoptera Noctuidae). Full length Slgallerimycin cDNA encodes a 75-amino acid protein sharing 80-95% amino acid sequence identity with the defensin-like antifungal peptide gallerimycin, and phylogenetic analysis reveals that Sl-gallerimycin is closely related to other known lepidopteran gallerimycin genes. Using quantitative real-time PCR (RT-qPCR) analysis, we show that Sl-gallerimycin expression is very low in naive larvae but can be strongly induced in larval fat bodies by the entomopathogenic fungus Nomuraea rileyi (Farlow) Samson. Knocking-down Sl-gallerimycin transcripts by dsRNA interference accelerates death in insects infected with N. rileyi. This is the first report showing that Sl-gallerimycin plays a significant role in resisting N. rileyi infection.