Pseudomonas Strains Naturally Associated with Potato Plants Produce Volatiles with High Potential for Inhibition of Phytophthora infestans

Abstract

ABSTRACTBacteria emit volatile organic compounds with a wide range of effects on bacteria, fungi, plants, and animals. The antifungal potential of bacterial volatiles has been investigated with a broad span of phytopathogenic organisms, yet the reaction of oomycetes to these volatile signals is largely unknown. For instance, the response of the late blight-causing agent and most devastating oomycete pathogen worldwide,Phytophthora infestans, to bacterial volatiles has not been assessed so far. In this work, we analyzed this response and compared it to that of selected fungal and bacterial potato pathogens, using newly isolated, potato-associated bacterial strains as volatile emitters.P. infestanswas highly susceptible to bacterial volatiles, while fungal and bacterial pathogens were less sensitive. CyanogenicPseudomonasstrains were the most active, leading to complete growth inhibition, yet noncyanogenic ones also produced antioomycete volatiles. Headspace analysis of the emitted volatiles revealed 1-undecene as a compound produced by strains inducing volatile-mediatedP. infestansgrowth inhibition. Supplying pure 1-undecene toP. infestanssignificantly reduced mycelial growth, sporangium formation, germination, and zoospore release in a dose-dependent manner. This work demonstrates the high sensitivity ofP. infestansto bacterial volatiles and opens new perspectives for sustainable control of this devastating pathogen.