The NLR Protein Encoded by the Resistance Gene Is Triggered by the Replication-Associated Protein Rep/C1 of Tomato Yellow Leaf Curl Virus.

The whitefly-transmitted tomato yellow leaf curl virus (TYLCV) is one of the most destructive viral pathogens of cultivated tomato. To combat TYLCV, resistance gene has been introduced into cultivated tomato () from wild tomato species by interspecific crossing. Introgression lines with contain a large inversion compared with , which causes severe suppression of recombination and has hampered the cloning of so far. Here, we report the fine-mapping and cloning of using crosses between a introgression line and several susceptible accessions. was shown to encode a nucleotide-binding leucine-rich repeat (NLR) protein. For breeding purposes, a highly specific DNA marker tightly linked to the gene was developed permitting marker-assisted selection. The resistance mediated by was effective against the Israel strain of TYLCV (TYLCV-IL) and tomato yellow leaf curl virus-[China : Shanghai2] (TYLCV-[CN : SH2]), but not against tomato yellow leaf curl Sardinia virus (TYLCSV) and leafhopper-transmitted beet curly top virus (BCTV). By co-infiltration experiments we showed that transient expression of the Rep/C1 protein of TYLCV, but not of TYLCSV triggered a hypersensitive response (HR) in plants co-expressing the gene. Our results indicate that the / gene of TYLCV-IL presents the avirulence determinant of mediated resistance.