Identification of pathogens causing apple Valsa canker in Xinjiang wild apple forests and antifungal effect of endophytic bacteria from medicinal plants on the pathogens

Abstract:

[Background] Endophytic bacteria of medicinal plants can produce the same or similar compounds as host plants and new secondary metabolites, which can promote the growth of the host, resist diseases and insect pests, and degrade toxic and harmful compounds. [Objective] To further improve the biocontrol efficiency of apple Valsa canker, and enrich the resource pool of antagonistic strains of endophytic bacteria from medicinal plants in Xinjiang. [Methods] The pathogens of apple Valsa canker were isolated and identified from the branches with disease spots of the apple plants in the wild apple forests of Xinyuan County (Yili area) and Emin County (Tacheng area) in Xinjiang. The endophytic bacteria of medicinal plants, which had the ability against the pathogen of apple canker, were screened by plate confrontation method. [Results] A total of 234 strains of pathogenic fungi were isolated from Xinyuan county and Emin county, including 25 strains of Valsa malicola and 2 strains of V. mali. In addition, 92 strains of endophytic bacteria with antifungal effect were screened out, among which 70 strains were from Glycyrrhiza uralensis. [Conclusion] The medicinal plant G. uralensis is rich in microbial resources against apple Valsa canker. This study is of great significance for the biocontrol of apple Valsa canker in Xinjiang wild apple forests and the development and utilization of endophytic bacteria in medicinal plants.