Composition and diversity of phyllospheric microbial community in tobacco leaves infected by tobacco target spot disease

To investigate the phyllospheric fungal and bacterial community composition and diversity in tobacco leaves infected by tobacco target spot, the composition of fungal and bacterial communities in both diseased and healthy leaves were analyzed with Illumina high-throughput sequencing technology. The results showed that the phyllospheric fungi in diseased and healthy leaves mainly distributed in 2 phyla (Basidiomycota and Ascomycota), and the phyllospheric bacteria in diseased and healthy leaves mainly were Proteobacteria, Actinobacteria, Firmicutes, etc. For diseased leaves, the dominant genera of fungi were Thanatephorus, Stagonosporopsis, Alternaria, and Didymella, and those of bacteria were Pantoea, Pseudomonas, and Enterobacter. For healthy leaves, the dominant genera of fungi were Alternaria, Neoascochyta, Didymella, Stagonosporopsis, and Cladosporium, and those of bacteria were Pseudomonas, Pantoea, and Enterobacter. The diversity, richness, and coverage indices of the fungal communities in diseased leaves were lower than those in healthy leaves. The diversity index of the bacterial community in diseased leaves was higher, while the richness and coverage indices were lower than those of healthy leaves. The functional prediction results indicated that the functional floras of fungi in diseased leaves were mainly plant pathogen, animal pathogen-endophyte-plant pathogen-wood saprotroph, and endophyte-plant pathogen. The functional floras of fungi in healthy leaves were mainly animal pathogen-endophyte-plant pathogen-wood saprotroph and plant pathogen. The metabolic pathway of bacteria in both diseased and healthy leaves were mainly metabolism, genetic information processing, and environmental information processing. The community compositions, relative abundance of species, and dominant species of fungi and bacteria in diseased and healthy leaves differed in varying degrees.