Genetically engineered transgenic plants with the Domain 1 sequence of tobacco mosaic virus 126 kDa protein gene are completely resistant to viral infection

In many plant RNA viruses, Domains 1, 2 and 3 are conserved in replicase pr oteins. In order to examine the interference of viral replication by the Do main 1 sequence, we generated transgenic plants transformed with DNA corres ponding to the Domain 1 sequence of the TMV 126 kDa protein. This DNA seque nce includes the TMV RNA from nucleotides 1 to 2,149, which comprises both the 5'-untranslated and methyl transferase region. The transgenic plants ob tained showed complete resistance to TMV infection. The presence of the Dom ain 1 sequence in the plants completely prevented local necrosis in Nicotia na tabacum cv, Xanthi nc, and any systemic development of symptoms in Nicot iana tabacum Xanthi upon TMV inoculation. Most transgenic plants sustained the conferred resistance even under TMV inoculum concentrations up to as hi gh as 1,000 mu g/ml. To detect any accumulation of TMV coat protein or vira l RNA in infected transgenic plants, immunochemical tests and Northern blot analyses were carried out. Neither viral RNA or coat protein was detectabl e in the systemic leaves of the completely resistant transgenic plants, whe reas they were accumulated in large quantities in all of the control plants . Because of the conservation of Domain 1 in many plant RNA viruses, the ac quisition of resistance to virus infection using the Domain 1 sequence appe ars to be a very effective strategy for breeding of viral resistant plants.