Bacterial volatiles play important roles in mediating beneficial interactions between plants
and their associated microbiota. Despite their relevance, bacterial volatiles are mostly studied under
laboratory conditions, although these strongly differ from the natural environment bacteria encounter
when colonizing plant roots or shoots. In this work, we ask the question whether plant-associated
bacteria also emit bioactive volatiles when growing on plant leaves rather than on artificial media.
Using four potato-associated Pseudomonas, we demonstrate that potato leaves offer sufficient nutrients
for the four strains to grow and emit volatiles, among which 1-undecene and Sulfur compounds
have previously demonstrated the ability to inhibit the development of the oomycete Phytophthora
infestans, the causative agent of potato late blight. Our results bring the proof of concept that bacterial
volatiles with known plant health-promoting properties can be emitted on the surface of leaves
and warrant further studies to test the bacterial emission of bioactive volatiles in greenhouse and
field-grown plants.