Cd inhibits powdery mildew colonization and reconstructs microbial community in leaves of Sedum alfredii

Understanding the influence of heavy metal (Cd) on the phyllosphere microbiome of hyperaccumulator plants is important for optimizing phytoremediation. The phyllosphere characteristics of Sedum alfredii, a hyperaccumulator, were investigated by 16S rRNA and ITS amplicon sequencing after it had been infected or uninfected by powdery mildew. Here, we found that the colonization of powdery mildew can cause a serious chlorosis and necrosis in leaves of S. alfredii. However, S. alfredii preferred accumulated higher concentration of Cd in the infection leaves, which significantly inhibited the powdery mildew colonization in leaves. Compared with the infection S. alfredii, the relative abundance of Leotiomycetes was dramatically decreased, the Alpha and Beta-diversity of phyllosphere microbiome significantly increased with the Cd treatment. Furthermore, the interkingdom networks in the infected leaves with the Cd treatment presented a higher number of nodes and edges, and the highest modularity more complex and in interkingdom than infected leaves, which indicated a highly connected microbial community. These results suggest that Cd significantly inhibits powdery mildew colonization by altering the phyllosphere microbial community in leaves of Sedum alfredii. That pave the way toward efficiently heavy metal phytoremediation and the new perspective of heavy metal defense strategy.