Action of a nematode-trapping fungus shows lectin-mediated host–microorganism interaction

Abstract

Many nematode-trapping fungi capture nematodes using an adhesive present on specific capture organs (for review see ref. 1). Until recently, the mechanism of adhesion was completely unknown. In the case of Arthrobotrys oligospora, one of the most common nematophagous fungi, nematodes are trapped in three-dimensional structures of the adhesive network type (Fig. 1a). When a suspension of nematodes is added to an agar culture of the fungus, nematodes are immediately captured and firmly held by the traps. The nematode cuticle is lysed at the point of contact and penetrated by a hypha within one hour2. An increased secretion by the fungus of a mucilaginous substance in the presence of prey has been shown by scanning and transmission electron microscopy2,3. Our hypothesis is that the firmness of attachment to the traps despite the struggle of the nematode is due to a series of events, beginning with an interaction between complementary molecular configurations on the nematode and fungal surfaces. We show evidence here for the presence of a lectin on the traps of A. oligospora which binds to a carbohydrate on the nematode surface.