Status and advancement of root-knot nematode management strategies and the emerging CRISPR/Cas biotechnology application

Root-knot nematodes (RKNs), Meloidogyne spp., exhibit a broad host range, threatening more than 3000 species of plants, including agriculturally important crops such as cotton (Gossypium hirsutum), tomato (Lycopersicon esculentum) and rice (Oryza sativa). Among the over 90 RKN species, the four most prevalent are M. incognita, M. arenaria, M. javanica, and M. hapla, with M. incognita being the most damaging. This paper reviewed the current RKN management strategies, including chemical nematicides, biological control, crop rotation, and resistant varieties, with a focus on the application of the revolutionary CRISPR/Cas genome editing tool in developing RKN resistance in plants. CRISPR/Cas has been widely utilized for improving crop traits due to its specificity, streamline, and inheritability. Recent progress has demonstrated the simplicity and robustness of CRISPR/Cas technology in improving plant traits. Among these, the development of nematode resistance by CRISPR/Cas knocking out of plant compatibility factors in model and commercial plants, has achieved significant progress. This review summarizes the RKN parasitism mechanisms and plant compatibility factors that would be promising CRISPR/Cas targets. The fundamentals and key aspects of CRISPR/Cas genome editing technology are addressed and discussed, and an example experimental pipeline for developing nematode resistance in cotton is described.