Barley MLA3 recognizes the host-specificity effector Pwl2 from Magnaporthe oryzae

  • Published:
  • Authors: Brabham HJ, Gómez De La Cruz D, Were V, Shimizu M, Saitoh H, Hernández-Pinzón I, Green P, Lorang J, Fujisaki K, Sato K, Molnár I, Šimková H, Doležel J, Russell J, Taylor J, Smoker M, Gupta YK, Wolpert T, Talbot NJ, Terauchi R, Moscou MJ (2023)
  • Reference: Plant Cell. 2023 Oct 11:koad266. doi: 10.1093/plcell/koad266.

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 (Hordeum vulgare) NLR gene Mildew resistance locus a (Mla) has undergone functional diversification and the proteins encoded by different 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 the rice blast fungus Magnaporthe oryzae in a dosage-dependent manner. Using a forward genetic screen, we discovered that the recognized effector from M. oryzae is Pathogenicity toward Weeping Lovegrass 2 (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.

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