Eutrema japonicum is a perennial herb belonging to the Eutrema genus in the crucifer family. In recent years, numerous substances with notable pharmacological activities have been successfully isolated from E. japonicum. Despite significant advancements in related research, the efficacy of the rhizome extract of E. japonicum against root-knot nematodes remains unknown. In this study, the rhizome extract of E. japonicum was used as raw material to demonstrate the inhibitory and nematicidal effects of the extract on Meloidogyne enterolobii. The results showed that the LC₅₀ of the E. japonicum rhizome extract on second-stage juveniles (J2s) was 69.590 mg/mL and 22.336 mg/mL at 24 h and 48 h after treatment, respectively. The mortality rate of J2s reached 88.93% at 48 h post-treatment when the concentration was 200 mg/mL, and the inhibition rate of single-egg hatching reached 88.14%. This study analyzed the chemical composition of the ethanol extract of E. japonicum, and 10 organosulfur compounds and lipid compounds with insecticidal and antibacterial effects were preliminarily screened out. Among them, sec-butyl isothiocyanate and geraniol were further investigated for their nematicidal activity, demonstrating high efficacy against M. enterolobii. Moreover, we conducted network pharmacology analysis and RT-qPCR analysis to predict the potential inhibitory mechanisms of sec-butyl isothiocyanate and geraniol on M. enterolobii. These findings offer a scientific foundation and theoretical framework for utilizing E.japonicum as a potential raw material for developing novel natural plant nematicides.

Kenaf (Hibiscus cannabinus L.), a member of the Malvaceae family, has gained increasing research interest owing to its therapeutic attributes. Among pathogens affecting tropical kenaf cultivation, Meloidogyne enterolobii is the most economically destructive disease, causing severe yield loss and quality deterioration. Consequently, the identification of M. enterolobii-resistant kenaf germplasms and the elucidation of the underlying molecular pathways are primary objectives for plant breeders. In this study, the gene encoding a TGA-like protein associated with root-knot nematode resistance was cloned from kenaf via reverse transcription polymerase chain reaction (RT-PCR) and the rapid amplification of cDNA ends (RACE), and designated as HcTGA5 gene. The full-length cDNA is 798 bp, encoding a 230-amino acid protein (GenBank accession: PZ944973). The application of phytohormones (jasmonic acid, JA; salicylic acid, SA; ethylene, ET) profoundly affected HcTGA5 gene expression with specific temporal patterns: peak expression was observed at 6 h after ET treatment, followed by 48 h after SA, and 24 h after JA treatment. HcTGA5 gene demonstrated an ‘initial upregulation followed by decline’ trend in response to ET treatment, whereas SA and JA triggered a ‘rise–fall–rise’ fluctuation. The data demonstrate the temporal modulation of HcTGA5 gene expression by phytohormones, suggesting its function in hormone-mediated defense signaling. A comparative analysis revealed markedly elevated HcTGA5 gene expression in M. enterolobii-resistant germplasms compared to susceptible ones, indicating its possible association with nematode resistance. In conclusion, HcTGA5 gene may play an integral role in kenaf’s defense against M. enterolobii. The study establishes a basis for investigating the nematode resistance mechanisms of kenaf and gives a theoretical framework for the genetic enhancement and disease management of kenaf.