Piriformospora indica, Verticillium dahliae, phytohormones, defense, calcium, EIN3
The soil-borne vascular pathogen Verticillium dahliae (Vd) causes severe wilt symptoms in a wide range of plants. The microsclerotia produced by this pathogen survive in soil for longer than 15 years. The beneficial endophytic fungus Piriformospora indica (Pi) reduces Verticillium mediated disease development in Arabidopsis. Pretreatment of Arabidopsis roots with Pi protects plants from Verticillium infection, the plants survive better and the production of Vd microsclerotia is dramatically reduced. This is mainly caused by re-pression of Vd growth in the host. Thus, the beneficial fungus Pi is an efficient bio-control agent that protects Arabidopsis from Vd infection. Furthermore, Vd-induced disease development requires the ethylene-activated transcription factor EIN3, and Pi-mediated increase of plant performance is partially depending on auxin. We discuss the role of phytohormones and phytohormone signaling in these plant/microbe interaction.