An NB-LRR gene, TYNBS1, is responsible for resistance mediated by the Ty-2 Begomovirus resistance locus of tomato

Key message An NB-LRR gene, TYNBS1 , was isolated from Begomovirus -resistance locus Ty - 2. Transgenic plant analysis revealed that TYNBS1 is a functional resistance gene. TYNBS1 is considered to be synonymous with Ty - 2 . Tomato yellow leaf curl disease caused by Tomato yellow leaf curl virus (TYLCV) is a serious threat to tomato ( Solanum lycopersicum L.) production worldwide. A Begomovirus resistance gene, Ty - 2, was introduced into cultivated tomato from Solanum habrochaites by interspecific crossing. To identify the Ty - 2 gene, we performed genetic analysis. Identification of recombinant line 3701 confirmed the occurrence of a chromosome inversion in the Ty - 2 region of the resistant haplotype. Genetic analysis revealed that the Ty - 2 gene is linked to an introgression encompassing two markers, SL11_25_54277 and repeat A (approximately 200 kb). Genomic sequences of the upper and lower border of the inversion section of susceptible and resistant haplotypes were determined. Two nucleotide-binding domain and leucine-rich repeat-containing (NB-LRR) genes, TYNBS1 and TYNBS2 , were identified around the upper and lower ends of the inversion section, respectively. TYNBS1 strictly co-segregated with TYLCV resistance, whereas TYNBS2 did not. Genetic introduction of genomic fragments containing the TYNBS1 gene into susceptible tomato plants conferred TYLCV resistance. These results demonstrate that TYNBS1 is a functional resistance gene for TYLCV, and is synonymous with the Ty - 2 gene.