Phyllosphere microbiome responses to spray-induced gene silencing targeting Phytophthora infestans in potato

Recent years have seen a growing interest in the use of RNA interference to control filamentous pathogens, creating a new niche in plant disease management. Strategies like spray-induced gene silencing (SIGS) offer effective and environmentally friendly alternatives to chemical disease control but remain underexplored. Given the profound influence of microbiomes on plant health and crop productivity, knowledge of how spraying double-stranded RNAs (dsRNAs) can impact plant microbial communities is needed to facilitate the transition of SIGS from the laboratory to practical large-scale use. We have therefore investigated changes in the bacterial and fungal communities of the phyllosphere in the economically important potato plant after spraying with dsRNA targeting the phytopathogen Phytophthora infestans. Spraying with dsRNA alone had little effect on the relative abundance of the dominant species found in the native potato phyllosphere. However, there were small time-dependent changes in the composition of the bacterial communities, and much larger changes in bacterial community metrics were observed after P. infestans inoculation. We also observed maintenance of potentially beneficial bacterial genera in dsRNA-treated plants in addition to composition changes linked to the plant's natural defense response upon P. infestans infection. Together, these observations support the view that dsRNA spraying enables safe and targeted pathogen control in potato.