Background

Rust and smut fungi are plant pathogens which cause diseases of considerable relevance in agriculture. Both fungi are biotrophic and require living plant tissue for proliferation. Instead of killing their host plants, they manipulate host cells to assure that these sustain fungal growth. During the infection, the fungi release an entire cocktail of so-called effectors which function either in the interaction zone between fungus and host or are delivered to plant cells. Effector proteins suppress plant immunity and promote parasitic infection. At present, the mechanism how effectors of plant-pathogenic fungi end up in plant cells remains a mystery.