Chromosome-level genome assembly of the nematophagous flatworm Luticola nematophagus reveals molecular adaptations for predation and biocontrol potential

The soil-dwelling Rhabdocoelan flatworm Luticola nematophagus, recently identified as a specialized predator of plant-parasitic nematodes (e.g., Meloidogyne incognita), exhibits significant potential as a biocontrol agent for agricultural nematode diseases. We report the first chromosome-level genome assembly of L. nematophagus, generated by integrating PacBio HiFi long-read sequencing with Hi-C chromatin conformation capture. The assembled genome spans 899.92 Mb (Scaffold N50 = 231.83 Mb) and contains 50.08% repetitive sequences and 45,225 predicted protein-coding genes. Genome completeness was assessed using CEGMA (94.76%) and BUSCO (85.49%) metrics. Comparative genomic analyses identified significant expansions in gene families associated with neural signaling, environmental adaptation, and nematode predation, encompassing synaptic vesicle components, metalloendopeptidases, antioxidant enzymes, transmembrane transporters, peptidases, lipases, and detoxification components. These gene family expansions likely underpin L. nematophagus' adaptations to soil ecosystems and specialized predation strategy, potentially facilitating nematode cuticle digestion and toxin neutralization. Notably, L. nematophagushas lost the regenerative capabilities characteristic of Triclad flatworms (e.g., Dugesia japonica, Schmidtea mediterranea). In contrast, it prioritizes resource allocation towards reproductive adaptation through self-fertilization and high fecundity. Experimental validation in controlled pot trials confirmed its efficacy in suppressing tomato root-knot nematode disease. This finding highlights the role of its high reproductive output in sustaining predator population levels requisite for effective biocontrol. This study provides foundational genomic resources for elucidating the evolution of nematode predation within Platyhelminthes and advances the development of L. nematophagusas a scalable biocontrol agent.