Identification and Biocontrol Effect of Antagonistic Bacterium Bacillus velezensis BPC6 against Soft Rot and Sclerotinia Rot Diseases on Lettuce

doi:10.16409/j.cnki.2095-039x.2020.02.008

Abstract

Abstract: Soft rot and sclerotia rot are two destructive diseases in the production of lettuce. In order to effectively control these two diseases, an antagonistic strain BPC6 was isolated from the lettuce rhizosphere soil by using the plate dilution method and plate confrontation method. Its cell suspensions and cell-free filtrates are both capable of inhibiting the growth of the soft rot pathogen (Pectobacterium carotovorum) and the sclerotia rot pathogen (Sclerotinia sclerotiorum), as well as other 14 plant pathogens. The BPC6 strain was identified as Bacillus velezensis through its morphology, 16S rDNA and genome sequence analyses. Physiological and biochemical characteristics indicate that BPC6 could secrete cellulase and protease, and could not produce chitinase and siderophores. The growth curves of the BPC6 strain showed that it could grow under 1%-10% NaCl and pH 5.0-9.0. The optimum application amount of BPC6 was 1.4×10⁹-2.8×10⁹CFU/mL demonstrated by estimating the control effects of BPC6 at different concentrations on lettuce leaves (in vitro) inoculated with soft rot and sclerotia rot pathogens. The control efficacy of the BPC6 strain against lettuce soft rot and sclerotia rot in greenhouse was 44.09% and 53.58%, respectively. Field experiments showed that its control efficacy on lettuce sclerotia rot was 77.41%. This study suggested that B. velezensis BPC6 was a potential prospective biocontrol agent to control soft rot and sclerotia rot diseases on lettuce.

Key words: lettuce (Lactuca sativa), soft rot, sclerotia rot, Bacillus velezensis, identification, biocontrol effect

CLC Number:

S476

SUN Wangwang, YAN Li, CHEN Changlong, TIAN Yu, LI Xiaoying, CHEN Jie, XIE Hua. Identification and Biocontrol Effect of Antagonistic Bacterium Bacillus velezensis BPC6 against Soft Rot and Sclerotinia Rot Diseases on Lettuce[J]. Chinese Journal Of Biological Control, 2020, 36(2): 231-240.

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