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ARS Home » Midwest Area » St. Paul, Minnesota » Cereal Disease Lab » Research » Publications at this Location » Publication #399432

Research Project: Surveillance, Pathogen Biology, and Host Resistance of Cereal Rusts

Location: Cereal Disease Lab

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

item BRABHAM, HELEN - Sainsbury Laboratory
item GOMEZ DE LA CRUZ, DIANA - Sainsbury Laboratory
item WERE, VINCENT - Sainsbury Laboratory
item SHIMIZU, MOTOKI - Iwate Biotechnology Research Center
item SAITOH, HIROMASA - Tokyo University Of Agriculture & Technology
item HERNANDEZ-PINZON, INMACULADA - Sainsbury Laboratory
item GREEN, PHON - Sainsbury Laboratory
item LORANG, JENNIFER - Oregon State University
item FUJISAKI, KOKI - Iwate Biotechnology Research Center
item SATO, KAZUHIRO - Okayama University
item MOLNAR, ISTVAN - Institute Of Experimental Botany
item SIMKOVA, HANA - Institute Of Experimental Botany
item DOLEZEL, JAROSLAV - Institute Of Experimental Botany
item RUSSELL, JAMES - Sainsbury Laboratory
item TAYLOR, JODIE - Sainsbury Laboratory
item SMOKER, MATTHEW - Sainsbury Laboratory
item GUPTA, YOGESH - Sainsbury Laboratory
item WOLPERT, TOM - Oregon State University
item TALBOT, NICHOLAS - Sainsbury Laboratory
item TERAUCHI, RYOHEI - Iwate Biotechnology Research Center
item Moscou, Matthew

Submitted to: bioRxiv
Publication Type: Pre-print Publication
Publication Acceptance Date: 10/22/2022
Publication Date: 10/22/2022
Citation: Brabham, H.J., Gomez De La Cruz, D., Were, V., Shimizu, M., Saitoh, H., Hernandez-Pinzon, I., Green, P., Lorang, J., Fujisaki, K., Sato, K., Molnar, I., Simkova, H., Dolezel, J., Russell, J., Taylor, J., Smoker, M., Gupta, Y., Wolpert, T., Talbot, N.J., Terauchi, R., Moscou, M.J. 2022. Barley MLA3 recognizes the host-specificity determinant PWL2 from rice blast (M. oryzae). bioRxiv.

Interpretive Summary: Plants are routinely exposed to a diverse array of microbes that may be commensal (neutral), beneficial, or pathogenic. The plant immune system recognizes the presence of these microbes using diverse immune receptors that are encoded by the genome. There are two major classes of plant immune receptors that are classified by their location in the cell: membrane-localized extracellular receptors and intracellular receptors. Plant pathogens routinely secrete effectors into plant cells to interfere with the plant immune system. Effectors are highly sequence and structurally diverse molecules such as proteins or metabolites, evolving to evade plant recognition whilst also maintaining their ability to manipulate the plant to the advantage of the pathogen. The majority of our understanding of the plant immune system is derived from binary interactions, recent research suggests that plant immune receptors have a broader capacity to recognize pathogens than previously understood. Previous work had established that resistance in barley to rice blast (Magnaporthe oryzae) occurs in the same region as resistance to barley powdery mildew conferred by the resistance gene Mla3. Using a genetic approach, we discovered that the resistance gene Mla3 confers resistance to rice blast and barley powdery mildew. To identify the effector that is recognized by Mla3, we next used a genetic approach in rice blast to discover that Mla3 recognizes PWL2, an effector previously shown to be involved in limiting the host range of rice blast on weeping lovegrass (Eragrostis curvula). Collectively, this work shows that a single immune receptor has gained the capacity to recognize effectors from diverse pathogens, highlighting our limited understanding of how these immune receptors evolve to recognize plant pathogens.

Technical 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.