Plant resistance genes against nematodes: Mechanisms and genetic resources in crop protection

Plants are continuously faced by a diverse array of biotic stressors throughout their life cycle, including nematodes, fungi, bacteria, insects, viruses and weeds, many of which severely compromise growth, physiology, and yield. Among these, plant-parasitic nematodes (PPNs) are particularly damaging and complex adversaries due to their close interactions with plant root systems and their resilience in soil ecosystems. Notably, cyst nematodes (Heterodera and Globodera spp.), lesion nematodes (Pratylenchus spp.) and root-knot nematodes (Meloidogyne spp.) cause extensive damage across a wide range of crops, resulting in billions of dollars in annual agricultural losses. Their rapid dissemination via irrigation and agricultural tools, combined with limited effectiveness and sustainability of chemical control methods, highlights the urgent need for stable and environmentally safe solutions. Genetic resistance offers one of the most promising and sustainable strategies for nematode management. Over recent decades, numerous resistance genes have been identified and characterized in a wide range of plant species by different research groups. Studies in crops such as tomato, pepper, potato, sugar beet, cereals, and soybean have revealed diverse genetic loci conferring resistance against various nematode species. This review combines the scattered data available in the literature to provide a comprehensive assessment of plant resistance genes against nematodes. While addressing a wide range of plant species and resistance mechanisms, its classification of genes on a plant-specific basis enhances the accessibility of the text for readers from diverse agricultural fields. Furthermore, by summarising the molecular mechanisms and genetic foundations of nematode resistance, it offers a comparative perspective on the major resistance genes present in key agricultural crops. By synthesising recent advances, this manuscript seeks to guide future research and contribute to the development of nematode-resistant varieties, thereby supporting sustainable plant protection.