Photodynamic Inactivation reduces the diversity and changes the composition of bacterial and fungal communities associated with leaf surfaces

Plant surfaces are colonized by a myriad of microorganisms including mutualistic strains and pathogens. Particularly in agricultural systems applications are required that protect the plants against pathogens without negative side effects on the environment and humans. Photodynamic Inactivation (PDI) has been demonstrated to be a promising approach to efficiently fight plant pathogens. Based on its mechanism of action, the light-induced and photosensitizer-mediated overproduction of reactive oxygen species in target cells, PDI is likely to generally inactivates microorganisms on plants irrespective of their pathogenicity. In order to prove this hypothesis we used next-generation 16S rRNA gene amplicon sequencing to characterize the bacterial and fungal communities associated with leaf surfaces of Arabidopsis thaliana before and after the photodynamic treatment using the chlorine e6 derivative B17-0024 as photoactive compound and showed that this treatment reduced the microbial richness and altered the microbial community composition. These findings may help to develop effective pathogen-control strategies and may also stimulate research on plant-microbe interactions exploiting the potential of PDI.