Tomato Tm-2 2 gene confers multiple resistances to TMV, ToMV, PVX, and PVY to cultivated potato

Viral infection seriously affects the yield and quality of potato tubers. Breeding of virus-resistant potato (Solanum tuberosum L.) varieties is essential. Introduction of resistance genes from other Solanaceae species into cultivated potato is likely to be a valuable method to achieve durable resistance to potato virus. Tm-2 2 resistance gene was cloned from tomato cv. KBV and introduced into the binary vector pBIN19 to yield Tm-2 2-constitutive expression vector under the control of the CaMV 35S promoter. The resultant vector was transferred into potato, and Tm-2 2 gene was successfully expressed in transgenic potato plants. After infection with TMV, ToMV, PVX, and PVY, transgenic potato plants showed the high level of resistance to these viruses, and potato tuber yield was significantly increased compared to wild type. qRT-PCR results showed that Tm-2 2 transgenic plants had much lower transcript levels of VIRUS-COAT genes than wild type, even no TMV- and ToMV-COAT RNAs were detected in upper non-inoculated systemic leaves of transgenic lines. These results indicate that Tm-2 2 confers different resistance responses against viruses depending on its expression level.