SUMMARY. Plant viruses significantly decrease the yield of cultivated plants; therefore, developing new methods of combating viral diseases and studying the effectiveness of these methods is relevant. The expression of the heterologous extracellular RNase gene of Zinnia elegans (ZRNase II) increases the resistance of transgenic plants to viruses. We have proposed a model system for visualizing the protective effect of the ZRNase II gene and studying the spread of GFP-marked viral particles in Nicotia-na benthamiana plants. The presence of the target ZRNase II gene was confirmed in the plants obtained after Agrobacterium-mediated transformation. Four lines were selected and adapted to ex vitro conditions. Total RNase activity in all transgenic lines was 4–8 times higher than in wild-type plants. We studied the systemic spread of the Potato virus X-based PVX-GFP construct in these plants. To this end, agroinfiltration was performed using the pICH27566 and pICH6692 vectors. Following agroinfiltration, transient expression of GFP occurred, spreading systemically throughout the plant due to transport proteins within the virus-like particles. Expression of the heterologous RNase gene (ZRNase II) delayed the spread of viral particles for 5–30 days, and reduced the accumulation of GFP-marked viral particles in all transgenic lines compared to the control. To assess the rapid systemic response of plants to agroinfiltration and virus expression, the content of chlorophyll and anthocyanins in N. benthamiana leaves was studied outside the zone of visual spread of GFP-marked viral particles. Differences were found between control and transgenic plants in terms of anthocyanin content in response to infection. Expression of the RNase II gene in plants delayed the systemic spread of virus-like particles, and altered the response to biotic stress at the level of plant secondary metabolism.
Keywords: genetic transformation, Solanaceae, Nicotiana benthamiana, Agrobacterium, PVX-GFP, systemic virus movement, virus resistance
