The Impact of Sugarcane Brown Rust and Host Resistance on the Phyllosphere Bacterial Community

Phyllosphere bacteria play a vital role in plant health and growth, and their assembly is governed by plant genotypes and pathogen attacks. However, there are few studies on how sugarcane cultivars and the pathogen Puccinia melanocephala shape the bacterial community of the sugarcane phyllosphere. In this study, the phyllosphere bacterial communities from three cultivars with various levels of resistance to P. melanocephala were compared through high-throughput sequencing of the V5 and V7 variable regions of the 16S rRNA gene. In addition, the influence of plant infection with P. melanocephala on the phyllosphere bacterial composition and diversity was examined. The results demonstrated host resistance and the pathogen infection shape the phyllosphere bacterial community of sugarcane. The principal coordinate analysis (PCoA) based on weighted UniFrac distances indicated that there were significant differences in the bacterial communities between susceptible and resistant cultivars and that the susceptible cultivar possessed relatively complex bacterial communities. Furthermore, the pathogen infection significantly varied the bacterial composition and diversity of sugarcane phyllosphere, resulting in the highest Shannon and Simpson indexes. MetagenomeSeq analysis revealed that Methylobacterium , Pantoea, and Pelomonas were biomarker taxa in the diseased sugarcane phyllosphere. These findings revealed a profile of sugarcane phyllosphere bacterial communities and illustrated the relationship between the phyllosphere microbiome, the plant pathogen, and the host genotype.