Archivio Journal of Plant Pathology

Abstract:

Plants expressing viral sequences may show homology- dependent virus resistance (HDR), which is characterized by specific degradation of transgenic RNA and viral RNAs homologous to the transgene. This resistance mechanism is a form of post-transcriptional gene silencing (PTGS), which can be suppressed by virus-encoded proteins. We analysed the effect of Potato virus Y, Cucumber mosaic virus and Potato virus X infections on HDR to Cymbidium ringspot virus (CymRSV) shown by Nicotiana benthamiana transgenic line 92KA1 expressing the full-length replicase gene of CymRSV. We observed breaking of resistance in transgenic plants doubly infected with PTGS suppressor viruses and CymRSV. The need of considering the effect of PTGS suppressor viruses on resistance or PTGS-dependent phenotype in transgenic crops is discussed.