 powdery mildew and rust fungi are two types of pathogenic fungi that cause severe damage to plants. These fungi use specialized structures called hostoria 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 hostoria. One type of protein, called YKFWXC, proteins, has been found to be particularly abundant in the hostoria of both powdery mildew and rust fungi. These proteins are composed of a small number of amino acids, including tyrosine, phenylalanine, tryptophan, and cysteine, all of which are arranged in a specific order, YFWXC. This unique arrangement suggests that the YFWXC proteins may play important roles in the interaction between the fungus and its host plant. This article was authored by Emerson Yeppie, Zhong Siguar, Pedersen Karsten, and others.