摘要
Root knot nematodes cause serious damage to global agricultural production annually. Given that traditional chemical fumigant nematicides are harmful to non-target organisms and the environment, the development of biocontrol strategies has attracted significant attention in recent years. In this study, it was found that theBacillus thuringiensisBerliner strain NBIN-863 exhibits strong fumigant nematicidal activity and has a high attraction effect onMeloidogyne incognita(Kofoid and White) Chitwood. Four volatile organic compounds (VOCs) produced by NBIN-863 were identified using solid-phase microextraction and gas chromatography–mass spectrometry. The nematicidal activity of four VOCs, namely,N-methylformamide, propenamide, 3-(methylthio)propionic acid, and phenylmalonic acid, was detected. Among these compounds, 3-(methylthio)propionic acid exhibited the highest direct contact nematicidal activity againstM. incognita, with an LC50 value of 6.27 μg/mL at 24 h. In the fumigant bioassay, the mortality rate ofM. incognitatreated with 1 mg/mL of 3-(methylthio)propionic acid for 24 h increased to 69.93%. Furthermore, 3-(methylthio)propionic acid also exhibited an inhibitory effect on the egg-hatching ofM. incognita. Using chemotaxis assays, it was determined that 3-(methylthio)propionic acid was highly attractive toM. incognita. In pot experiments, the application of 3-(methylthio)propionic acid resulted in a reduction in gall numbers, decreasing the number of galls per gram of tomato root from 97.58 to 6.97. Additionally, the root length and plant height of the treated plants showed significant increases in comparison with the control group. The current study suggests that 3-(methylthio)propionic acid is a novel nematicidal virulence factor ofB. thuringiensis. Our research provides evidence for the potential use of NBIN-863 or its VOCs in biocontrol against root knot nematodes.
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