MicroRNAs in plant-parasitic nematodes: what are they and why should we care?

Plant-parasitic nematodes (PPNs) establish intimate interactions with their host plants, leading to significant economic losses worldwide. The molecular mechanisms underlying parasitism are complex, requiring tight regulation of numerous genes. MicroRNAs (miRNAs), small non-coding RNAs, regulate gene expression at the post-transcriptional level by binding to target messenger RNAs. However, the diversity and functional roles of miRNAs in PPNs are only beginning to be uncovered. This review summarizes the current knowledge on the nature, biogenesis, functions, and trafficking of miRNAs in PPNs. Beyond advancing our understanding of gene regulation throughout the nematode life cycle and during parasitism, miRNA characterization holds significant promise for novel control strategies. Emerging evidence suggests that miRNAs may function across kingdoms, modulating gene expression in host plants during parasitic interactions. We highlight compelling examples from other pathosystems and discuss preliminary findings on miRNA-mediated communication between PPNs and their hosts. Finally, we provide an overview of the main computational tools and databases available for identifying and predicting miRNAs and their targets, aimed at supporting researchers interested in this emerging field.