Euonymus japonicus phyllosphere microbiome is significantly changed by powdery mildew

Euonymus japonicus Thunb. is a woody and ornamental plant popular in China, Europe and North America. Powdery mildew is one of the most serious diseases that affect E. japonicus growth. In this study, the diseased and apparently healthy leaves were collected from E. japonicus planted in a greenbelt in Beijing, and the effect of powdery mildew on the epiphytic microbial community was investigated by using Illumina sequencing. The results showed that the healthy leaves (HL) harbored greater bacterial and fungal diversity than diseased leaves (DL). Furthermore, both bacterial and fungal communities in DL exhibited significantly different structures from those in HL. The relative abundance of several bacterial phyla (Proteobacteria and Firmicutes) and fungal phyla (Ascomycota and Basidiomycota) were altered by powdery mildew. At the genus level, most genera decreased as powdery mildew pathogen Erysiphe increased, while the genera Kocuria and Exiguobacterium markedly increased. Leaf properties, especially protein content was found to significantly affect beta-diversity of the bacterial and fungal community. Network analysis revealed that positive bacterial interactions in DL were stronger than those in HL samples. Insights into the underlying the indigenous microbial phyllosphere populations of E. japonicus response to powdery mildew will help in the development of methods for controlling plant diseases.