Interkingdom Transfer of the Acne-Causing Agent, Propionibacterium acnes, from Human to Grapevine

Here, we report the surprising and, to our knowledge, unique example of horizontal interkingdom transfer of a human opportunistic pathogen (Propionibacterium acnes) to a crop plant (the domesticated grapevine Vitis vinifera L.). Humans, like most organisms, have established a long-lasting cohabitation with a variety of microbes, including pathogens and gut-associated bacteria. Studies which have investigated the dynamics of such associations revealed numerous cases of bacterial host switches from domestic animals to humans. Much less is, however, known about the exchange of microbial symbionts between humans and plants. Fluorescent in situ hybridization localized P. acnes in the bark, in xylem fibers, and, more interestingly, inside pith tissues. Phylogenetic and population genetic analyses suggest that the establishment of the grapevine-associated P. acnes as obligate endophyte is compatible with a recent transfer event, likely during the Neolithic, when grapevine was domesticated.