Identification and complete genome sequence analysis of the pathogen causing mango bacterial dry rot

Mango bacterial dry rot has become an increasingly serious issue in the mango-producing regions of Guangdong, China, leading to dry and necrotic leaves and branches. In order to identify the causal agent of this disease and determine its taxonomic status, the causative bacteria were isolated and characterized through pathogenicity tests, morphological observations, culture feature assessments, 16S rRNA gene sequence assays, and complete genome sequencing. The results revealed that the causal agent belongs to Sphingomonas sanguinis . The pathogenic bacterium, strain NY01, is gram-negative, forms a yellow lawn, has a rod-shaped structure with a cell size of approximately 0.7 to 1.4 µm, and possesses a single polar flagellum with slow motility. The 16S rRNA gene sequence of strain NY01 showed 99% sequence identity with Sphingomonas sanguinis . Strain NY01 has an optimal growth temperature of 28°C and can tolerate a salinity range of 0.1–3.0%. It is capable of utilizing glucose for energy under both aerobic and anaerobic conditions. The complete genome of strain NY01 consists of one chromosome (3,280,800 bp) and three plasmids (275,887 bp, 143,601 bp, and 37,326 bp), containing 3,593 predicted genes, 59 transfer RNA (tRNA) sequences, and 12 rRNA sequences. This study clarified the taxonomic status of the pathogenic bacteria, analyzed the biological characteristics of the pathogenic bacteria, and explored pathogenic factors. These findings can serve as a theoretical basis for understanding the occurrence and progression of the disease, as well as for implementing effective prevention and control measures.