Objective This study was conducted to isolate and identify the pathogen causing leaf spot of wild Vaccinium myrtillus L. in its native habitat in Xinjiang, screen highly effective biocontrol strains, and fill the gap in systematic research on local pathogens of this disease.
Methods Pathogenic fungi were isolated and purified from field-collected diseased leaves by the tissue isolation method, and pathogenicity verification was performed according to Koch’s postulates. Pathogen identification was accomplished on the basis of colony morphology, microscopic characteristics and ITS sequence analysis. The mycelial growth rate method was used to determine the mycelial inhibition rate of three antagonistic Bacillus antagonistic strains against the pathogenic fungus.
Results Fungal strain HB1 was isolated from diseased tissues of Vaccinium myrtillus L. with leaf-spot symptoms. It was identified as Chaetomium globosum through morphological observation and ITS-sequence alignment. Pathogenicity tests confirmed that this fungus could induce typical leaf-spot symptoms on Vaccinium myrtillus L. Biological assays showed that the strain could grow at 25-37 ℃, with an optimum growth temperature of 37 ℃. It could tolerate pH values ranging from 4 to 13, and its optimum pH was 5. Bacillus amyloliquefaciens SS-12 showed the best antifungal performance, with a mycelial inhibition rate of 65.97%.
Conclusion This study is the first to confirm that Chaetomium globosum is the causal pathogen of leaf spot on Vaccinium myrtillus L. in Xinjiang. The highly-effective biocontrol strain SS-12 obtained in this study provides theoretical support for green disease prevention and control as well as disease-resistant germplasm breeding in the artificial cultivation of Vaccinium myrtillus L.
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