Susceptibility to virus infection of transgenic tobacco plants expressing structural and nonstructural genes of tobacco rattle virus.

Tobacco plants were transformed with the coat protein (CP) genes and several nonstructural genes of tobacco rattle virus (TRV) strains PLB and TCM. Accumulation of RNA transcripts from the integrated viral genes was detectable in all types of transformants. Plants expressing CP were resistant to infection with virions of the homologous strain but susceptible to infection with RNA of the homologous strain or nucleoprotein of the heterologous strain. No resistance was detectable in plants transformed with the nonstructural 13K and 16K genes of strain PLB, or with the 29K gene that is unique to RNA-2 of strain TCM. When protoplasts from plants expressing TCM-CP were inoculated with TCM virions, there was a normal production of genomic RNAs and CP but the synthesis of mRNA and protein corresponding to the 16K gene was selectively defective. Because this defect was not observed when protoplasts from plants expressing PLB-CP were inoculated with PLB virions, it probably plays no role in the coat protein-mediated protection observed in transgenic plants.