Ty-1 confers resistance to geminivirus tomato curly top virus

Tomato curly top virus (ToCTV), a geminivirus first isolated from tomato in Japan, shares approximately 86% nucleotide sequence identity with common bean curly stunt virus. Despite its isolation from tomato, previous attempts to infect tomato using an infectious clone were unsuccessful, and its potential impact on tomato production has remained unclear. In this study, we reconstructed an infectious clone of ToCTV and evaluated its pathogenicity and the effectiveness of Ty-1-mediated resistance. ToCTV infected Nicotiana benthamiana and Nicotiana tabacum at high rates and induced more severe symptoms than tomato yellow leaf curl virus (TYLCV) strains IL and Mld, indicating high virulence in Nicotiana species. We optimized an agroinoculation method to establish ToCTV infection in tomato. Although the infection rate in a geminivirus-susceptible tomato genotype was lower than that of TYLCV, infected plants developed severe leaf curling and growth suppression. In contrast, a Ty-1-bearing tomato genotype had no visible symptoms and significantly reduced viral DNA, even under high inoculum pressure via graft inoculation. These results demonstrate that Ty-1-mediated resistance effectively restricts ToCTV infection and symptom development, suggesting that current Ty-1-based cultivars are likely to remain protected against this geminivirus.