THE SENSE AND ANTISENSE COAT PROTEIN GENE OF ALFALFA MOSAIC-VIRUS STRAIN N20 CONFERS PROTECTION IN TRANSGENIC TOBACCO PLANTS

The coat protein gene of a South Australian strain of alfalfa mosaic v irus (AMV-N20 [NcS]) has been cloned, sequenced, and transferred into Nicotiana tabacum L. cv. Xanthi via Agrobacterium tumefaciens under th e control of the CaMV 35S promoter. A number of lines (T-0 generation) were selected with the coat protein gene either in sense orientation (CP+) or in antisense orientation (CP-). The T-0 plants were tested fo r their gene expression and susceptibility to the homologous AMV strai n. A significant delay in the onset of symptoms and a reduction in vir us accumulation was observed in CPS plants mechanically inoculated wit h AMV. CP- plants were also significantly protected but less so than t he CPS plants. Plants transformed with the expression vector only (CP0 ) showed a minor resistance to local infection on inoculated leaves co mpared with untransformed plants. The strategy of coat protein mediate d protection (CPMP) using the CP gene in either messenger sense or ant isense would therefore be appropriate for testing on economically impo rtant pasture legumes.