Cytosolic activation of cell death and stem rust resistance by cereal MLA-family CC–NLR proteins

Abstract

Significance Stem rust caused by the fungus Puccinia graminis f. sp. tritici ( Pgt ) remains the major disease threat to wheat production. The Sr33 and Sr50 resistance proteins protect wheat against a broad spectrum of field isolates of Pgt and are closely related to the barley powdery mildew-resistance protein MLA10. Like MLA10, Sr33 and Sr50 possess signaling N-terminal domains that self-associate in planta and initiate cell-death signaling from the cytosol. However, Sr33 induces disease-resistance signaling from the cytosol but not from the nucleus of wheat cells, suggesting cytosolic activation of both cell death and stem rust resistance.