The nuclear inclusion b (NIb) replicase gene of a Chinese isolate of potato Y potyvirus was expressed in E. coli, and the rabbit antibody against replicase was prepared. In order to elucidate the resistant mechanism by PVY NIb gene, -1 frameshift NIb gene was obtained by use of site-mutating PCR. This -1 frameshift NIb gene (UN) was constructed into binary vector pBin438, and then transformed into tobacco NC 89 mediated by Agrobacterium tumefaciens LBA4404. Northern blot results showed that the...