Biomedical subjects

W G Dougherty

Publications and source records attributed to W G Dougherty.

39 records · Page 3Linked to original sources

PubMedDate not supplied

Pathogen-derived resistance to a potyvirus: immune and resistant phenotypes in transgenic tobacco expressing altered forms of a potyvirus coat protein nucleotide sequence.

Transgenic Nicotiana tabacum 'Burley 49' plants containing one of six different forms of the tobacco etch virus (TEV) coat protein (CP) nucleotide sequence have been generated. In whole plant studies, R1 and R2 progeny were inoculated mechanically with TEV, and the appearance and severity of symptoms were recorded. Symptom phenotype was altered, ranging from near wild type susceptibility to apparent immunity. Protoplasts derived from wild type and transgenic Burley 49 plant lines were transfected with TEV RNA. Protoplasts from transgenic plants expressing full-length or truncated forms of TEV CP supported virus replication. Protoplasts from certain transgenic plants, producing plus- or minus-sense CP transcripts but no CP, did not support virus replication at wild type levels. A model is proposed to account for these observations.

Amino Acid Sequence↗

PubMedDate not supplied

RNA-mediated resistance with nonstructural genes from the tobacco etch virus genome.

Sense RNA-mediated virus resistance has been described for transgenic plants expressing potyviral capsid protein sequences. This study was undertaken to determine if expression of other viral sequences could induce this type of virus resistance. Plants showing highly resistant or 'recovery' phenotypes were generated by expressing the tobacco etch virus (TEV) 6 kDa/21 kDa reading frames. Expression of translatable or untranslatable versions of this TEV sequence produced resistant lines. Highly resistant and recovery phenotype plants expressing TEV coat protein sequences. High transcription rates with low steady-state levels of the transgene transcript generally correlated with resistance. During recovery and induction of the resistance, RNA and protein steady-state levels decreased 5- to 20-fold, while transcription of the transgene continued at a similar level. A posttranscriptional, cellular system eliminating sequences contained in the transgene transcript and viral genome would be consistent with the results.

Base Sequence↗

PubMedDate not supplied

RNA-mediated virus resistance in transgenic plants: exploitation of a cellular pathway possibly involved in RNA degradation.

Transgenic Nicotiana tabacum cv. Burley 49 plants were generated that express the 5' untranslated region of the tobacco etch potyvirus (TEV) genome ligated to a mutated version of the TEV coat protein gene sequence that rendered it untranslatable. Eight different transgenic plant lines were analyzed for transgene expression and for resistance to TEV. Three different responses were noted when the transgenic plant lines were inoculated with TEV: 1) some were highly resistant, and no virus replication occurred; 2) some were susceptible but able to recover from systemic TEV infection; and 3) some were susceptible to TEV infection. Plant tissue displaying the recovery phenotype was analyzed for virus replication and transgene expression. Recovered tissue could not be infected with TEV and had steady-state transgene RNA levels which were five- to eightfold lower than those of unchallenged transgenic plant tissue. Nuclear runoff assays suggested a post-transcriptional reduction in specific RNA levels. The highly resistant and recovery phenotypes associated with TEV challenge inoculation and the reduction of steady-state RNA levels in recovered transgenic leaf tissue may be manifestations of a common mechanism.

Base Sequence↗