Recognitional specificity of the flax rust AvrP and AvrP123 effectors is determined by polymorphisms at their N-and C-termini
N. FARAH (1), A. Catanzariti (1), P. Dodds (2), A. Hardham (3), D. Jones (3) (1) Research School of Biology, ANU, Australia; (2) CSIRO, Australia; (3) Research School of Biology, ANU, Australia

Flax rust fungus effector proteins AvrP and AvrP123 are recognised by flax resistance proteins, P and P1, P2, P3, respectively. Variants of these effectors with different host-recognition specificities are found in the flax rust strains 271, 339, bs25 and WA. In this study, we investigated which regions in AvrP and AvrP123 are recognised by their cognate resistance proteins. We used Agrobacterium-mediated transient expression in tobacco (Nicotiana tabacum) and flax (Linum usitatissimum) to observe a Hypersensitive Response (HR)-like necrosis as an indicator of recognition. For AvrP, deletions were generated based on the structure of the protein, whereas domain swaps and mutations were generated based on amino acid polymorphisms present in the AvrP variant from strain 271, which is not recognised by any of the P, P1, P2 or P3 resistance proteins. From the structure of AvrP, we know that AvrP and AvrP123 each bind three zinc atoms. Mutational disruption of zinc binding in AvrP resulted in a loss of protein stability and recognition by P. We also discovered that key amino acid polymorphisms involved in AvrP recognition are located at the C-terminus. For AvrP123, deletions and domain swaps were generated based on amino acid polymorphisms present in AvrP123 variants from strains 339, bs25 and WA. We discovered that recognition or AvrP123 by P1 is determined by the mature N-terminus of the protein just after the signal peptide, whereas P2 and P3 recognise the C-terminus of AvrP123.

Abstract Number: P17-520
Session Type: Poster