广西玉林市番石榴焦腐病的病原菌鉴定

Identification of the pathogen causing guava black-rot in Yulin,Guangxi

In October 2019, guava (Psidium guajava) fruits were collected from Yulin, Guangxi, after kept indoors for 2-3 days, brown lesions were found on the blossom-end of the fruits with water-soaked haloes around the lesions. A lot of needle tip-sized dots produced at the centre of the lesions, which were subglobose pycnidia, and the conidia were colorless and nearly fusiform. Single spore strains were obtained by isolation and purification, and YLWB-BD01 was selected as representative strain for pathogenicity assay. After wound inoculation, similar symptoms with natural occurrence appeared. The fungus had the same morphological characteristics with YLWB-BD01 was re-isolated from the lesions. BLAST analysis of ITS, EF-1α and β-Tub sequences of YLWB-BD01 shown 100% homology with Botryosphaeria dothidea (Moug.) Ces. & De Not. Phylogenetic tree constructed by the concatenated sequences of ITS～EF-1α～β-Tub sequences shown that the strain YLWB-BD01 was clustered together with B. dothidea (CMW8000). Based on the morphological characteristics and phylogenetic analysis results, the pathogenic fungus causing guava black-rot was identified as B. dothidea. To our knowledge, this is the first report of guava black-rot caused by B. dothidea in China.