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The unconventional resistance protein PTR recognizes the Magnaporthe oryzae effector AVR-Pita in an allele-specific manner


Blast disease caused by the fungus Magnaporthe oryzae is one of the most devastating rice diseases. Disease resistance genes such as Pi-ta or Pi-ta2 are critical in protecting rice production from blast. Published work reports that Pi-ta codes for a nucleotide-binding and leucine-rich repeat domain protein (NLR) that recognizes the fungal protease-like effector AVR-Pita by direct binding. However, this model was challenged by the recent discovery that Pi-ta2 resistance, which also relies on AVR-Pita detection, is conferred by the unconventional resistance gene Ptr, which codes for a membrane protein with a cytoplasmic armadillo repeat domain. Here, using NLR Pi-ta and Ptr RNAi knockdown and CRISPR/Cas9 knockout mutant rice lines, we found that AVR-Pita recognition relies solely on Ptr and that the NLR Pi-ta has no role in it, indicating that it is not the Pi-ta resistance gene. Different alleles of Ptr confer different recognition specificities. The A allele of Ptr (PtrA) detects all natural sequence variants of the effector and confers Pi-ta2 resistance, while the B allele of Ptr (PtrB) recognizes a restricted set of AVR-Pita alleles and, thereby, confers Pi-ta resistance. Analysis of the natural diversity in AVR-Pita and of mutant and transgenic strains identified one specific polymorphism in the effector sequence that controls escape from PtrB-mediated resistance. Taken together, our work establishes that the M. oryzae effector AVR-Pita is detected in an allele-specific manner by the unconventional rice resistance protein Ptr and that the NLR Pi-ta has no function in Pi-ta resistance and the recognition of AVR-Pita.

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Fig. 1: NLR Pi-ta and Ptr loci and gene models.
Fig. 2: PtrA but not NLR Pi-ta is required and sufficient for AVR-Pitaa-triggered blast resistance.
Fig. 3: PtrB but not NLR Pi-ta mediates AVR-Pitaa detection in Pi-ta varieties.
Fig. 4: PtrA detects AVR-PitaGuy11.
Fig. 5: A cysteine at position 191/192 of AVR-Pita results in escape from detection by PtrB.
Fig. 6: Model for the allele-specific detection of AVR-Pita by Ptr.

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All data generated or analysed during this study are included in the paper and its supplementary information files or are available from the corresponding authors on reasonable request.


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Work in the lab of T.K. was funded by ANR projects Resistance Proteins (ANR-15-CE20-0007) and RePairs (ANR-21-CE20-0017). Work in the lab of B.Z. at IRRI was funded by Swiss National Science Foundation. M.B. was funded by an E.U. Marie Skłodowska-Curie individual fellowship (No. 896153). N.L. was funded by a PhD grant from the French Ambassy in Thailand and by Campus France. A.J. was supported by a visiting scholarship from the Iranian Ministry of Science, Research and Technology (28-11-2018). G.X. and J.W. were supported by the National Natural Science Foundation of China (32372505, U20A2021 and 32172422), the Major Science and Technology Project of Hunan Province (2021NK1001) and the Natural Science Foundation of Hunan Province of China (2021JJ30486).

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G.X., S.C., D.T., B.Z., J.W. and T.K. designed research. G.X., N.L., S.C., K.L., M.B., A.J., M.J.T.-Y., V.C. and I.M. performed research. G.X., N.L., S.C., K.L., M.B., A.J., E.F., D.T. and T.K. analysed data. G.X., S.C., B.Z., J.W. and T.K. acquired funding. G.X., N.L., S.C., M.B., D.T., B.Z. and T.K. wrote the paper.

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Correspondence to Bo Zhou, Jun Wu or Thomas Kroj.

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Xiao, G., Laksanavilat, N., Cesari, S. et al. The unconventional resistance protein PTR recognizes the Magnaporthe oryzae effector AVR-Pita in an allele-specific manner. Nat. Plants 10, 994–1004 (2024).

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