Isolation and Identification of Bacillus velezensis TMQ-VKSL-1 and Its Use for Biocontrol of Meloidogyne incognita Infection of Tomato
Fusarium spp.and Meloidogyne spp.are important plant pathogens,and the complex interaction between these two pathogens in the host plant that can lead to serious soil borne plant diseases.In this study,F.graminearum was used as the target pathogen to explore highly effective strains for biocontrolling of root knot nematode(RKN)dis-eases in tomatoes.A bacterial strain TMQ-KSL-1 with good antibacterial effect was isolated and screened from a long-term tomato monoculture greenhouse soil using dilution plating method.The strain was classified based on its morpho-logical,physiological and biochemical characteristics,and 16S rRNA gene sequence.The effects of different concen-trations of TMQ-KSL-1 fermentation broth and fermentation supernatant on the RKN eggs hatching rate and the lethal rate of the second instar larvae of RKN were determined.The inhibition effect of the fermentation broth on RKN disea-ses was also analyzed through pot experiments.The results showed that strain TMQ-KSL-1 had strong nematicidal ac-tivity,and the inhibition rates of nematode egg hatching were 94.76％and 90.72％after 48 hours of treatment with its fermentation broth and fermentation supernatant,respectively.The corrected mortality rates of the second instar lar-vae of tomato RKN after 24-h treatment of fermentation broth and supernatant were 100％and 97.37％,respectively.The 100 and 200-fold fermentation broth of strain TMQ-KSL-1 reduced tomato RJN disease by 59.54％and 12.14％,respectively,and the biocontrol effect of 100-fold fermentation broth was equivalent to that of 500-fold fermentation broth of avermectin(61.56％).Both the fermentation broth and supernatant increased underground fresh weight by 90.95％and 19.65％respectively,indicating that the strain has a growth promoting effect on tomato roots.There-fore,strain TMQ-KSL-1 has the ability to prevent and control tomato RKN diseases,and has market development and application prospects.
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