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 u ndertaken to determine if expression of other viral sequences could in duce this type of virus resistance. Plants showing highly resistant or 'recovery' phenotypes were generated by expressing the tobacco etch v irus (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 had biochemical hallma rks observed with resistant plants expressing TEV coat protein sequenc es. High transcription rates with low steady-state levels of the trans gene transcript generally correlated with resistance. During recovery and induction of the resistance, RNA and protein steady-state levels d ecreased 5- to 20-fold, while transcription of the transgene continued at a similar level. A posttranscriptional, cellular system eliminatin g sequences contained in the transgene transcript and viral genome wou ld be consistent with the results.