Terrific protein traffic: the mystery of effector protein delivery by filamentous plant pathogens

Abstract

Many biotrophic fungal and oomycete plant pathogens deliver effector proteins directly into host cells during infection. Recent advances are revealing the extensive effector repertoires of these pathogens and are beginning to shed light on how they manipulate host cells to establish a parasitic relationship. Surprisingly, oomycete effectors seem to share a common uptake system with those from the human malaria pathogen. The current explosion of information is opening new research avenues in molecular plant pathology and is providing new opportunities to limit the impact of plant disease on food production.

Fig. 1

Organization of haustoria and the presumed route of effector delivery. Haustoria emerge from extracellular pathogen infection structures (such as spores or hyphae) and enter plant cells through the infection peg by invaginating the host plasma membrane. Haustoria are surrounded by the pathogen plasmalemma and cell wall as well as the modified host plasma membrane (extrahaustorial membrane). These membranes enclose the extrahaustorial matrix, an interface zone that is sealed by the neck band. The inset illustrates the delivery of a pathogen effector (red) with an N-terminal secretion tag (purple) through the secretory pathway and into the host cell.