Analysis of transgenic tobacco plants expressing a truncated form of a potyvirus coat protein nucleotide sequence.

Transgenic Nicotiana tabacum cv. Burley 49 plants were generated which expressed a tobacco etch virus (TEV) coat protein (CP) gene construct containing a stop codon positioned at codon 147. This gene construct was expected to produce a TEV CP lacking the carboxy-terminal 118 amino acids of the full-length 264 amino acid CP. TEV CP gene transcripts of the expected size could be detected in transgenic plants but the expected truncated CP could not be detected. Ten independent transgenic lines expressing this form of the TEV CP gene were examined in detail. Two transgenic plant lines were resistant to aphid- or mechanically transmitted TEV and one line was highly resistant. Protoplasts derived from the highly resistant plant line did not support virus replication. The data suggested that the expression of this mutated form of the TEV CP gene could interfere with TEV replication and displayed features associated with RNA-mediated virus resistance.