The Chemical Composition and Nematicidal Activity of Wasabi (Eutrema japonicum) Rhizome Extract Against Meloidogyne enterolobii

<i>Eutrema japonicum</i> is a perennial herb belonging to the <i>Eutrema</i> genus in the crucifer family. In recent years, numerous substances with notable pharmacological activities have been successfully isolated from <i>E. japonicum</i>. Despite significant advancements in related research, the efficacy of the rhizome extract of <i>E. japonicum</i> against root-knot nematodes remains unknown. In this study, the rhizome extract of <i>E. japonicum</i> was used as raw material to demonstrate the inhibitory and nematicidal effects of the extract on <i>Meloidogyne enterolobii</i>. The results showed that the LC₅₀ of the <i>E. japonicum</i> 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 <i>E. japonicum</i>, 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 <i>M. enterolobii</i>. Moreover, we conducted network pharmacology analysis and RT-qPCR analysis to predict the potential inhibitory mechanisms of sec-butyl isothiocyanate and geraniol on <i>M. enterolobii</i>. These findings offer a scientific foundation and theoretical framework for utilizing <i>E.japonicum</i> as a potential raw material for developing novel natural plant nematicides.