Evaluation of virus resistance conferred by the NSs gene sequences from Tomato spotted wilt virus in transgenic plants

Transgenic Nitcoticma benthamiana expressing the sense NSs gene sequence from Tomato spotted wilt virus (TSWV) was further transformed with the sense or antisense NSs gene sequence. Three sense and 10 antisense lines with two transformations (hereafter referred to as "double-transformed lines") that were expected to contain only the sense and both sense and antisense NSs gene sequences, respectively, were examined for homology-dependent virus resistance using the unrelated virus, Potato virus X containing the NSs gene sequence. As a result, it was shown that two antisense double-transformed lines contained plants that were symptom-free. Furthermore, both lines accumulated a small-interfering RNA. These results suggest that RNA silencing was operating in both lines. However, the lines exhibited little or no resistance to TSWV.