A novel Arthrobotrys species : taxonomic characterization, nematicidal activity, and multi-omics insights into nematode predation

Abstract

ursaphelenchus xylophilus, the pinewood nematode (PWN), is a devastating invasive pest responsible for widespread mortality in global conifer forests. During a survey of bark beetle-associated fungi, a nematode-trapping fungus was isolated from an empty beetle gallery in Pinus thunbergii. ITS sequence analysis suggested it represented a novel species. This study aimed to characterize the fungus taxonomically and evaluate its biocontrol potential against PWN. Multi-locus phylogenetic analyses (ITS, TEF1-α, RPB2) confirmed the isolate as a new species, Arthrobotrys byssisimilis sp. nov. Morphological examination revealed adhesive trapping networks and distinctive ellipsoidal conidia. Enzymatic assays demonstrated chitinase and protease activity, with optimal conditions defined for pH and temperature. Culture filtrates, protein extracts, and secondary metabolites showed rapid, dose-dependent nematicidal effects, achieving 100 % PWN mortality within 10–30 min. The fungus exhibited strong tolerance to pine-derived volatiles (α-pinene, β-pinene, turpentine, and ethanol), indicating high adaptability to the host environment. Whole-genome sequencing revealed a 36.97 Mb genome with 8,354 predicted genes, including 104 proteases, 8 chitinases, and diverse secondary metabolite biosynthesis clusters. Transcriptomic profiling after nematode exposure identified 638 differentially expressed genes, including virulence-related enzymes (proteases, CAZymes), cytochrome P450s, and PHI factors, with evidence of stage-specific regulation. Arthrobotrys byssisimilis is the first Arthrobotrys species reported from a bark beetle gallery, expanding the ecological scope of the genus. The integrated in vitro nematicidal activity, physiological adaptability, and multi-omics data suggest A. byssisimilis warrants further evaluation as a potential biocontrol agent against PWN, while its unique genomic features provide new molecular targets for investigating fungal-nematode interactions. HIGHLIGHTS • Discovered novel nematode-trapping fungus Arthrobotrys byssisimilis. • Achieved 100% pinewood nematode kill in 10–30 mins using culture filtrates and extracts. • Shows strong tolerance to pine volatiles, ensuring better field adaptability. • Genome shows 104 proteases, 8 chitinases as major virulence factors. • Found 638 genes differentially expressed under nematode stress, stage-specific virulence.