Cloning and characterization of cuticle-degrading serine protease from nematode-trapping fungus Arthrobotrys musiformis

•The serine protease gene of Arthrobotrys musiformis was cloned and characterized.•Roles of serine protease in trapping fungi verified by selection force analysis.•Genes regulating fungal bioactivity can be explored by similar approach.

Plant parasitic nematodes represent a critical threat to global agriculture and ecosystems, and biocontrol methods are becoming increasingly attractive as a means to combat nematode infestation. Nematode-trapping fungi are a potentially useful biocontrol option, but further research to enhance fungal pathogenicity will be needed before deployments are feasible. It is known that nematode-trapping fungi can secrete cuticle-degrading serine proteases, which act as key mediators of virulence against nematodes. Here, we describe the cloning and characterization of the cuticle-degrading serine protease gene, AmSP1, from the nematode-trapping fungus Arthrobotrys musiformis. Phylogenetic and selection force analysis revealed a high degree of conservation of the AmSP1 catalytic and binding sites with previously described serine proteases from other nematode-trapping fungi. The dN/dS ratio of all six aligned-nematode-trapping fungi cuticle-degrading serine proteases was less than 1, as was the case of 386 individual codons, suggesting that the cuticle-degrading serine protease gene has undergone purifying selection and is evolutionarily important for this group of fungi.