Co-transplantation of phyllosphere and rhizosphere microbes promotes microbial colonization and enhances sugarcane growth

Increasing evidence suggests that microbes colonizing both above- and below-ground parts of plants are critical for plant growth and agricultural productivity. However, the extent to which the interactions between above- and below-ground microbial communities affect microbial colonization and plant performance is not fully understood. To address this question, we performed a phyllosphere and rhizosphere microbiome transplantation experiment (MT-Exp) using sugarcane, followed by microbiome profiling with 16S rRNA amplicon sequencing. Plant phenotypic observation exhibited that transplanting field-grown sugarcane phyllosphere and/or rhizosphere onto sugarcane plantlets in a controlled growth condition significantly increased total biomass compared to un-transplanted plants. Notably, co-transplantation of phyllosphere (P) and rhizosphere (R) microbiomes (PR treatment) resulted in the most pronounced plant growth promotion. A comparison of alpha diversity revealed that microbiome transplantation enhanced the species richness of both phyllosphere and rhizosphere communities. Additionally, PERMANOVA results showed that microbiome transplantation strongly impacted the rhizosphere microbial community, while no significant differences were observed in the phyllosphere microbes. The PR treatment was found to be more effective in introducing a greater diversity of microbial taxa than single transplantation (P and R treatments), of which many of these transplanted taxa were recognized as plant growth-promoting bacteria (PGPB). Furthermore, the PR network displayed denser connectivity between above- and below-ground components compared to all other treatments. In conclusion, our findings highlight the interdependence of above-ground and below-ground microorganisms, demonstrating their indispensable role in colonizing and promoting sugarcane growth.