Phyllosphere microbiome variations in response to leaf disease in citrus

Like the microbiome in the rhizosphere, the phyllosphere microbiome can have an important role in plant growth and health. However, whether and how the phyllosphere microbiome responds to the invasion of pathogens is not well understood. Here, through DNA metabarcoding (16S for bacteria and ITS for fungi) and shotgun metagenomic sequencing, we found that the phyllosphere microbiome in different ecological niches (epiphytes and endophytes) responded differently to melanose disease (infected by Diaporthe citri) on tangerine leaves. Several phenomena were identified in the diseased leaves over healthy leaves, including increasing microbial richness, reducing community evenness, enriching microbes and enhancing microbial interactions. Based on the differences at the microbial and the functional level, we further discuss their relationship with plant health. Finally, we propose a conceptual paradigm to describe the different microbial community assembly processes for the phyllosphere microbiome in response to leaf disease. Our results provide novel insights for understanding the contributions of the community response process in phyllosphere to the plant hosts when facing pathogen invasion.