Isolation and Identification of the Causal Pathogens for Kiwifruit Bacterial Canker and the Isolation of the Antagonistic Endophytic Fungi From Kiwifruit in Sichuan, China

Abstract

The kiwifruit bacterial canker has been recognized as the main kiwifruit pathogen in Sichuan and acquired strong resistance to chemicals during its long evolution under chemical evolutionary pressure. Base on biochemical testing, pathogenic testing and phylogenetic analyses, the results shown that Pseudomonas syringae pv. actinidiae is the causal agents of the “Hongyang” kiwifruit bacterial canker disease. Besides this bacterial pathogen, 14 endophytic fungi of kiwifruit leaves were also isolated and identified, including Penicillium sp. Colletotrichum sp. Phomopsis sp. Alternaria sp. and Nigrospora sp. 8 endophytic fungi were obtained from branches, such as Alternaria sp. Nigrospora sp. Phomopsis sp.and Sordaria sp. and one of the endophytic fungi Nigrospora sp. (No.J2) from branch showed good antagonistic activities to Pseudomonas syringae pv. actinidiae in vitro with the inhibition zone of 14 mm, therefore it has the potential of being used as a biological control agent against kiwifruit bacterial canker.