Broad-spectrum inhibition of Phytophthora infestans by root endophytes

* Phytophthora infestans (Phy. infestans) is a devastating pathogen of tomato and potato. It readily overcomes resistance genes and applied agrochemicals. Fungal endophytes provide a largely unexplored avenue of control against Phy. infestans. Not only do endophytes produce a wide array of bioactive metabolites, they may also directly compete with and defeat pathogens in planta.\n\n* Twelve fungal endophyte isolates from different plant species were tested in vitro for their production of metabolites with anti-Phy. infestans activity. Four well-performing isolates were evaluated for their ability to suppress nine isolates of Phy. infestans on plates and in planta.\n\n* Two endophytes reliably inhibited all Phy. infestans on plates, of which Phoma eupatorii isolate 8082 was the most promising. It nearly abolished infection by Phy. infestans in planta.\n\n* Here we present a biocontrol agent, which can inhibit a broad-spectrum of Phy. infestans isolates. Such broadly acting inhibition is ideal, because it allows for effective control of genetically diverse pathogen isolates and may slow the adaptation by Phy. infestans.