Identification of Streptomyces strain S16 and evaluating its biocontrol potential a-gainst Plasmodiophora brassicae
[Objective]In order to find new biocontrol resources to address the increasing severity of cruciferous vegetable clubroot disease.[Method]In our study,485 strains of bacteria were isolated from the rhizosphere soil of only a few healthy Chinese cabbage plants in the field of serious clubroot disease.Using Phytophthora capsici as an indicator fungus,we screened the biocontrol strains of cabbage clubroot disease by plate standoff and greenhouse pot experiment.Morphological characteristics and 16S rDNA sequence were used to identify the biocontrol bacteria.The stability of biocontrol bacteria was measured by heat treatment,acid-base treatment,ultraviolet treatment and protease K treatment.At the same time,the plate confrontation method was used to determine the antibacterial spectrum of the bacteria.[Result]46 biocontrol strains with antibacterial effects were obtained through standoff culture screening,and one strain with good control effect on Chinese cabbage clubroot disease was obtained through pot experiment re-screening.The strain S16 is relatively sensitive to high tempera-tures above 60 ℃,not sensitive to ultraviolet radiation and has strong UV stability.The stability is good after pH treatment at 4～8,and enzyme treatment has almost no effect on the antibacterial substances produced by the strain.Based on morphological characteristics and phylogenetic analysis,the strain was identified as Streptomyces griseoaurantiacus.S16 has inhibitory effects on Phytophthora capsici and other 7 pathogenic fungi,with a wide antibacterial spectrum,and a pot culture control effect of 68.74％on Chinese cabbage root swelling disease.[Conclusion]This indicates that S.griseoaurantiacus strain S16 has significant control effects on the clubroot disease of the cruciferous vegetable,and can be further developed into a biocontrol bacterium.
Cruciferous cropsClubroot diseaseStreptomyces griseoaurantiacusBiological control
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