The Effect of Host-Induced <em>Me-chs-1</em> Gene Silencing on the Pathogenicity of <em>Meloidogyne enterolobii</em>

Due to its broad climatic adaptability, extensive host range, robust ability to overcome re-sistance genes, and high pathogenicity, M. enterolobii has emerged as one of the most de-structive roots knot nematodes. Conventional root knot nematode resistance genes are in-effective against this species, as it can reproduce on crops carrying common resistance loci. Chitin, a major structural component of the nematode eggshell and cuticle, is synthesized by chitin synthase (CHS), an enzyme essential for regulating nematode development and re-production. Previous studies have demonstrated that silencing chitin synthase genes en-hances plant resistance to root knot nematodes; however, to date, no investigations have targeted chitin synthase genes in M. enterolobii specifically. In this study, we cloned a full-length chitin synthase gene (Me-chs-1) from M. enterolobii with a 3,788-bp coding sequence (CDS) encoding a 1,261-amino acid protein. Based on amino acid multiple sequence align-ment and phylogenetic tree analysis, the gene was designated Me-chs-1. Furthermore, three silencing vectors targeting the conserved domain of Me-chs-1 were constructed. Host-induced gene silencing (HIGS) was employed to suppress the chitin synthase gene in M. en-terolobii. Results demonstrated that all three vectors efficiently silence Me-chs-1. Compared to wild-type controls, the RNAi-treated groups exhibited significant reductions in gall number, egg-mass number, eggs per mass, and total egg count. The most effective RNAi line showed decreases of 76.12% in gall number, 82.35% in egg mass number, 62.44% in eggs per mass, and 82.73% in total egg count. Acid fuchsin staining revealed that nematodes in the RNAi-treated groups were notably smaller than in their wild-type counterparts, with delayed de-velopment and even developmental malformations, thereby tomato resistance to M. enter-olobii was enhanced. Transcriptome sequencing analysis identified a total of 501 differential-ly expressed genes (DEGs), and further pathway interaction network analysis revealed a po-tential indirect regulatory network between the chitin biosynthesis pathway and the Wnt signaling pathway. This research provides a novel direction for root-knot-nematode-resistant breeding and the development of innovative nematicides.