Different Abilities of Delivery Ways for dsRNA Expressed by Bacteria to Protect Tobacco from Co-infection with PVY and TMV

RNA interference (RNAi) is a plant self-resistant reaction and regulatory mechanism, which has been extensively studied in recent years. Prokaryotic expression of dsRNA can induce RNAi, conferring the plant resistance to virus. Plants were usually infected by various viruses in growth. In this study, two hot-spot gene sequences from Tobacco mosaic virus (TMV) and Potato virus Y (PVY) were selected and six hpRNA vectors including single-viral and two-viral chimeric genes were constructed. The target dsRNA could be induced, and virus resistance to mixed dsRNA A (derived from two kinds of single-viral genes) was compared to the resistance to dsRNA B (derived from one kind of two-viral chimeric gene) under the same conditions through multiple delivery methods. The result showed that dsRNA which was induced by bacterial prokaryotic expression system through two delivery methods could protect tobacco plants from infecting with PVY and TMV, the resistant efficiency of the mixed dsRNA A was more effective than dsRNA B, with the best resistant efficiency being 42.43%. Northern blot analysis of siRNA showed that the resistance was RNA-mediated virus resistance.