Abstract:[Objective] Root-knot nematode is destructive and difficult to be controlled. Virgibacillus dokdonensis MCCC 1A00493 is antagonistic to Meloidogyne incognita in vitro. In this study, we isolated and identified the nematicidal compound in the fermentation broth of MCCC 1A00493 and explored the modes of action, aiming at laying a theoretical foundation for the effective control of plant pathogenic nematodes.[Methods] The nematicidal compound in the supernatant of MCCC 1A00493 fermentation broth was isolated and purified by silica gel column chromatography and semi-preparative high-performance liquid chromatography, and the structure of the purified product was identified by liquid chromatography-mass spectrometry and nuclear magnetic resonance. The repellent activity, trapping activity, fumigation activity, and egg hatching-inhibiting activity of the compound were tested.[Results] The compound was identified to be 4-vinylphenol, which had the contact activity, fumigation activity, egg hatching-inhibiting activity, repellent activity at high concentration, and trapping activity at low concentration against the nematodes. At 15 μg/mL, 4-vinylphenol demonstrated contact activity, as manifested by the high corrected death rate (71.23%±9.06%) of M. incognita after 72 h. At 20 mg/mL, it showed fumigation activity and the death rate was 100% after 24 h. Inhibition rate of M. incognita egg hatching reached 66.2% after 10 days of exposure to 100 μg/mL 4-vinylphenol. Nematodes were repelled by 10 mg/mL, but attracted by 1 mg/mL 4-vinylphenol on agar plates. In Pluronic gel, nematodes were repelled by 25 mg/mL, and attracted and killed by 5 and 10 mg/mL 4-vinylphenol.[Conclusion] The compound 4-vinylphenol, identified from V. dokdonensis, possessed multiple modes of action against M. incognita, especially the repellent effect at high concentration and trapping effect at low concentration. Thus, it can be used as a potential bionematicide.
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