Fungal pathogenicity Wolfgang

Introduction Fungi are eukaroytic, carbon-heterotrophic microorganisms. To satisfy their need for organic nutrients, most fungal species live a saprophytic lifestyle. A small minority, however, has acquired the capability to develop on living plants, often causing disease in the host. These specialists have found a way to negate the plant defense machinery which consists of a multitude of defense mechanisms (for reviews see [1–3]). Hence, fungal pathogenicity results from the evolution of mechanisms that allow the transition of a saprophyte to a pathogen and that adapt fungal development to their host plants [4–6]. Before the real confrontation between fungi and plants can take place, however, fungi need efficient strategies for invasion of the plant’s outer fortifications (Figure 1). This review will, therefore, focus on signaling aspects of these early stages of pathogenesis.