The Rysto immune receptor recognises a broadly conserved feature of potyviral coat proteins

Knowledge of the immune mechanisms responsible for viral recognition is critical for understanding durable disease resistance and successful crop protection. We determined how potato virus Y (PVY) coat protein (CP) is recognised by Ry_sto , a TNL immune receptor. We applied structural modelling, site-directed mutagenesis, transient overexpression, co-immunoprecipitation, infection assays and physiological cell death marker measurements to investigate the mechanism of Ry_sto -CP interaction. Ry_sto associates directly with PVY CP in planta that is conditioned by the presence of a CP central 149 amino acids domain. Each deletion that affects the CP core region impairs the ability of Ry_sto to trigger defence. Point mutations in the amino acid residues Ser₁₂₅ , Arg₁₅₇ , and Asp₂₀₁ of the conserved RNA-binding pocket of potyviral CP reduce or abolish Ry_sto binding and Ry_sto -dependent responses, demonstrating that appropriate folding of the CP core is crucial for Ry_sto -mediated recognition. Ry_sto recognises the CPs of at least 10 crop-damaging viruses that share a similar core region. It confers immunity to plum pox virus and turnip mosaic virus in both Solanaceae and Brassicaceae systems, demonstrating potential utility in engineering virus resistance in various crops. Our findings shed new light on how R proteins detect different viruses by sensing conserved structural patterns.

Extreme resistance to Potato virus Y in potato carrying the Rysto gene is mediated by a TIR-NLR immune receptor

Potato virus Y (PVY) is a major potato (Solanum tuberosum L.) pathogen that causes severe annual crop losses worth billions of dollars worldwide. PVY is transmitted by aphids, and successful control of virus transmission requires the extensive use of environmentally damaging insecticides to reduce vector populations. Ry_sto , from the wild relative S. stoloniferum, confers extreme resistance (ER) to PVY and related viruses and is a valuable trait that is widely employed in potato resistance breeding programmes. Ry_sto was previously mapped to a region of potato chromosome XII, but the specific gene has not been identified to date. In this study, we isolated Ry_sto using resistance gene enrichment sequencing (RenSeq) and PacBio SMRT (Pacific Biosciences single-molecule real-time sequencing). Ry_sto was found to encode a nucleotide-binding leucine-rich repeat (NLR) protein with an N-terminal TIR domain and was sufficient for PVY perception and ER in transgenic potato plants. Ry_sto -dependent extreme resistance was temperature-independent and requires EDS1 and NRG1 proteins. Ry_sto may prove valuable for creating PVY-resistant cultivars of potato and other Solanaceae crops.