Adhesion to nematodes of conidia from the nematophagous fungus Drechmeria

Conidia of the endoparasitic nematophagous fungus Drechmeria coniospora adhere to the sensory organs of many nematode species. In some cases the adhesion phase is followed by penetration of the nematode cuticle and subsequent infection. In a study of eight different nematode species and five strains of the fungus only two species were infected: Panagrellus vedivivus was infeted by all strains and Ditylenchus dipsaci was infected by four strains, although the conidia of all fungal strains adhered to all of the nematode species tested. Treatment of the nematode P. redivivus and the conidia of D. coniospora with proteases gave a decreased adhesion in contrast to glycosidases, lipases and other enzymes tested. Inhibitory effects on adhesion were obtained after treatment of conidia with the carbohydrate N-acetylneuraminic acid and the amino acids alanine and proline. Hydrophobicity and electrical charge appear not to be involved in conidial adhesion. A previous hypothesis on the presence of a sialic-acid-specific lectin in this interaction appears to be incorrect and the present results indicate no involvement of carbohydrates in the adhesion process. The results suggest that the adhesion is mediated by protein(s) in the adhesive part of the conidium binding to protein(s) excreted from the sensory organs of the nematodes.