Transgenic tobacco plants expressing dsRNA can prevent infection by Tobacco mosaic virus.

Inverted repeats of the partial movement protein gene (ΔMP) of Tobacco mosaic virus (TMV) were introduced into the plant expression vector pBin438, and the recombinant plasmids were transformed into Agrobacterium tumefaciens EHA105 by a tri-parental mating method. Fifty transgenic plants of Nicotiana tabacum cv. Yunyan 87 were obtained after Agrobacterium-mediated transformation. PCR and Southern blot analyses showed that the target gene had integrated into the tobacco plant genome. When transgenic tobacco plants were challenged with TMV, symptoms expression and triple antibody sandwich enzyme-linked immunosorbent assay (TAS-ELISA) showed that transgenic plants had three kinds of phenotypes in response to the virus infection: immune (10%), resistant (4%) and susceptible (86%). Northern blot analysis showed that the levels of target mRNA accumulation varied among transgenic tobacco lines and a negative correlation between target mRNA accumulation and virus resistance was observed. [ABSTRACT FROM PUBLISHER]