Comparative Genomics Analysis of Three Species of Root-Lesion Nematodes, <i>Pratylenchus</i> spp., Suggests an Intricate Evolutionary Origin of Effector Genes

Root-lesion nematodes of the genus <i>Pratylenchus</i>, which includes over 100 species, are among the most damaging plant-parasitic nematodes, affecting a wide range of crops globally. Their migration in and out of roots causes mechanical damage and necrosis, leading to significant yield losses worldwide. In this study, we generated high-quality genome assemblies for three <i>Pratylenchus</i> species, <i>P. penetrans</i>, <i>P. crenatus</i>, and <i>P. neglectus</i>, isolated from potato fields across Canada. Using in silico analyses, we performed comprehensive genome annotation, comparative gene family analysis, and life-stage-specific gene expression profiling to investigate candidate genes likely involved in host interactions. Horizontal gene transfer (HGT) events were also predicted using the Alienness vs Predictor tool, based on protein homology comparisons and phylogeny between metazoan and non-metazoan taxa. These analyses revealed unique genomic structures, expansions of effector genes, and putative HGT events that may contribute to parasite adaptability. Notably, in <i>P. crenatus</i> and <i>P. penetrans</i>, the diversification and expansion of effector repertoires, combined with species-specific HGT candidates, could suggest evolutionary adaptations to support a broad host range. In contrast, the more compact effectorome of <i>P. neglectus</i> points to a parasitic strategy based on broad acting effectors. Although these findings provide an initial genome-scale view of the molecular toolkit used by these nematodes, they are based on computational predictions and await functional validation. This study lays a foundation for future research into the molecular mechanisms underlying parasitism, host adaptation, and nematode evolution.