Multiple virus resistance in transgenic plants conferred by the human dsRNA-dependent protein kinase

We have developed a new strategy for engineering resistance to multiple viruses in plants. The strategy exploits the human double stranded (ds) RNA-dependent protein kinase (PKR). PKR is one of the interferon-induced enzymes. It confers viral resistance in mammals by inhibiting viral replication through the inactivation of the translational initiation factor, eIF-2α, upon activation by dsRNA. The human PKR gene was fused to the promoter of the Arabidopsis blue copper binding protein gene (BCB) that is induced rapidly in response to wounding. The chimeric gene cassette was introduced into tobacco plants. Expression of the PKR gene in transgenic tobacco plants was demonstrated by RNA gel blot analysis and autophosphorylation assay of an M_r 68,000 protein. The transgenic plants expressing the PKR gene showed significantly reduced viral symptoms or no viral symptoms at all, when challenged by different plant RNA viruses, such as Cucumber mosaic virus, Tobacco etch virus, or Potato virus Y. Thus, expression of a single component in the human interferon pathway, the PKR gene, can effectively confer resistance to multiple viruses in transgenic plants.