The fucose-specific lectin gene AOL_s00054g276 affects trap formation and nematocidal activity of the nematophagous fungus Arthrobotrys oligospora.

Nematode-trapping fungi are natural enemies of nematodes in nature. Arthrobotrys oligospora, a typical nematode-trapping fungus with a clear genetic background, can capture and infect nematodes by forming adhesive three-dimensional networks. Lectins, a class of glycoproteins containing glycosyl-specific recognition domains, play an important role in biological recognition. However, the fucose-specific lectins have rarely been studied regarding the process of preying on nematodes. In this study, we characterized the biological role of the fucose-specific lectin-encoding gene AOL_s00054g276 (g276) in A. oligospora. The gene g276 was first deleted based on homologous recombination, then the phenotype and nematocidal activity of the Δg276 mutant was evaluated. The results showed that the deletion of gene g276 delayed trap formation and weakened its nematocidal activity; however, mycelial growth, conidia production, conidial germination rates and adaption to environmental stresses were not affected. Our results suggest that the fucose-specific lectin-encoding gene g276 might be associated with the morphogenesis of this fungus, and its deletion resulted in a significantly low density of three-dimensional traps (P < 0.05) and a significantly low nematode-trapping efficiency (P < 0.001). These findings provide a basis for further elucidating the mechanism of A. oligospora preying on nematodes and lay a foundation for the development and utilization of fungal-derived lectins for nematode control in the future.