 Powdery mildew and rust fungi are two types of pathogenic fungi that cause severe damage to plants. These fungi use specialized structures called haustoria to gain access to the plant's tissues and steal nutrients. To protect themselves from the plant's defenses, the fungi produce a variety of effector proteins that are secreted into the plant cell through the haustoria. These effector proteins are composed of small, aromatic proteins with a specific motif at their beginning, YFWXC. This motif suggests that these proteins may play important roles in the interaction between the fungus and its host plant. This article was authored by Emerson Yeppie, John Ziguar, Pedeson Carston, and others.