Identification of Mulberry Bacterial Blight Caused by Klebsiella oxytoca in Bazhong, Sichuan, China

Abstract

To provide a scientific basis for controlling mulberry bacterial blight in Bazhong, Sichuan, China (BSC), this study aimed to isolate and purify pathogenic bacteria from diseased branches of mulberry trees in the region and to clarify their taxonomic status using morphological observation, physiological and biochemical detection, molecular-level identification, and the construction of a phylogenetic tree. A total of 218 bacterial strains were isolated from samples of diseased mulberry branches. Of these, 7 strains were identified as pathogenic bacteria based on pathogenicity tests conducted in accordance with Koch’s postulates. Preliminary findings from the analysis of the 16S rRNA sequence indicated that the 7 pathogenic bacteria are members of Klebsiella spp. Morphological observation revealed that the pathogenic bacteria were oval-shaped and had capsules but no spores. They could secrete pectinase, cellulase, and protease and were able to utilize D-glucose, D-mannose, D-maltose, and D-Cellobiose. The 7 strains of pathogenic bacteria exhibited the highest homology with Klebsiella oxytoca. This study identifies Klebsiella oxytoca as the causative agent of mulberry bacterial blight in BSC, laying the foundation for the prevention and control of this pathogen and further investigation into its pathogenic mechanism.