EN
Postranscriptional gene silencing, PTGS, is one of the important plant defense mechanisms induced during viral infection. The process is sequence-specific and results from the occurrence of dsRNA intermediate molecules generated during replication of viruses in the cytoplasm. The presence of dsRNA molecules activates the cascade of reactions in the host’s cells, leading to elimination of virus’ genetic material. In spite of its high efficiency, the PTGS can be inhibited by virus-encoded factors, usually proteins, that enable virus replication progress and spread of the pathogen in the host. In the study we used an experimental model in which stably expressed green fluorescent protein in Nicotiana benthamiana 16c plants, was locally silenced with hairpin RNA construct, whereas virus-encoded PTGS putative suppressors were delivered by infecting the plants with ToTV. We have shown that Tomato Torrado Virus-encoded factors can efficiently suppress PTGS induced in used tobacco plants infected with the ToTV. In contrast, in the leaves of N. benthamiana with induced PTGS we identified lower expression rate of the GFP when not infected with the virus. This observation indicates that ToTV encodes strong PTGS suppressor (or suppressors). Nature and mechanism of which will need to be determined in further research.