Screening and identification of antagonistic bacteria against bacterial disease in Pinellia ternata, and determination of its biocontrol efficacy

【Objective】 The aim was to explore antagonisitic bacteria against bacterial diseases in Pinellia ternata,which could provide theoretical basis for development and utilization of biocontrol bacterial resources as well as the efficient and green control of bacterial disease in P. ternata. 【Method】 Using 6 strains of pathogenic bacteria of Pinellia ternata as target strains, antagonistic bacteria were isolated and screened from the rhizosphere soil of infected Pinellia ternata. The strain was identified based on morphological, physiological and biochemical characteristics determination, molecular biology analysis. The in vivo efficacy of the antagonistic bacteria against bacterial diseases caused by Dickeya chrysanthemi, Pseudomonas extremorientalis and Pectobacterium carotovorum in Pinellia ternata, carrots, potatoes and cabbages was determined. The in vivo efficacy of the antagonistic bacteria against bacterial diseases in Pinellia ternata caused by the 3 pathogens was determined by pot experiments. The inhibitory effects of the antagonistic bacteria on 13 pathogenic fungi from traditional Chinese medicinal plants were assessed using the plate confrontation method, clarifying its inhibitory spectrum.【Result】A total of 106 bacterial strains were isolated from the rhizosphere soil of Pinellia ternata, among which strain WBT16 exhibited the best antagonistic effect against 6 pathogenic bacteria causing bacterial diseases in Pinellia ternata. It was identified asBacillus velezensis. In vitro efficacy tests showed that the strain WBT16 achieved 100% control efficacy against bacterial diseases in Pinellia ternata and carrots caused by Dickeya chrysanthemi, Pseudomonas extremorientalis and Pectobacterium carotovorum. in vivo efficacy tests demonstrated that strain WBT16 had the highest control efficacy of 76.92% against bacterial diseases in Pinellia ternata caused by Dickeya chrysanthemi, followed by 69.23% against diseases caused by Pectobacterium carotovorum and 62.50% against those caused by Pseudomonas extremorientalis, all exceeding 60.00%. The inhibitory spectrum analysis revealed that antagonistic bacteria WBT16 exhibited fine inhibitory effects against various pathogenic fungi. It showed the best inhibitory effect against Botrytis cinerea from Fritillaria hupehensis, with an inhibition rate of 86.02%, and relatively high inhibition rates of 80.51% and 79.89% against Sclerotium rolfsii and Sclerotinia sclerotiorum from Pinellia ternata respectively. 【Conclusion】 The antagonistic bacteria WBT16, isolated and screened from the rhizosphere soil of Pinellia ternata, demonstrates effective control against bacterial diseases in Pinellia ternata and exhibits a broad inhibitory spectrum. It holds great development value and application potential for the biological control of bacterial diseases in Pinellia ternata.