How filamentous pathogens co-opt plants: the ins and outs of fungal effectors

Research on effectors secreted by pathogens during host attack has dominated the field of molecular plant–microbe interactions over recent years. Functional analysis of type III secreted effectors injected by pathogenic bacteria into host cells has significantly advanced the field and demonstrated that many function to suppress host defense. Fungal and oomycete effectors are delivered outside the host plasma membrane, and although research has lagged behind on bacterial effectors, we are gradually learning more and more about the functions of these effectors. While some function outside the host cell to disarm defense, others exploit host cellular uptake mechanisms to suppress defense or liberate nutrients intracellularly. Comparative genomics suggests that the organization of effector genes drives effector evolution in many pathogen genomes.

► Pathogens secrete effectors to establish disease on their host.
► We review recent research progress on fungal and oomycete effectors.
► Apoplastic effectors disarm host defense.
► Some effectors are translocated to the host cytoplasm.
► Effectors are subject to accelerated evolution.