Barley MLA3 recognizes the host-specificity determinant PWL2 from rice blast (M. oryzae)

Abstract

Plant nucleotide-binding leucine-rich repeat immune receptors (NLRs) directly or indirectly recognize pathogen-secreted effector molecules to initiate plant defense. Recognition of multiple pathogens by a single NLR is rare and usually occurs via monitoring for changes to host proteins; few characterized NLRs have been shown to recognize multiple effectors. The barley NLR Mla has undergone functional diversification and Mla alleles recognize host-adapted isolates of barley powdery mildew (Blumeria graminis f. sp. hordei; Bgh). Here, we show that Mla3 also confers resistance to rice blast (Magnaporthe oryzae) in a dosage dependent manner. Using a forward genetic screen, we discovered that the recognized effector from M. oryzae is PWL2, a host range determinant factor that prevents M. oryzae from infecting weeping lovegrass (Eragrostis curvula). Mla3 has therefore convergently evolved the capacity to recognize effectors from diverse pathogens.