Transient expression of coding and non-coding regions of PVY confer resistance to virus infection

One of the most efficient mechanisms by which plants protect themselves from invading viruses is the specific RNA-dependent silencing pathway termed post-transcriptional gene silencing (PTGS). In this mechanism, resistance to a virus is engineered through the expression of a segment of the virus genomein transgenic plants. Potato VirusY (PVY) is one of the most damaging viruses of potato, infecting most cultivars and causing significant yield losses throughout the world. The present study was performed to compare the efficiency of three construct containing different regions of 3′UTR (UR) and coat protein (CP) against PVY infection. Expression of homologous hairpin RNA to PVY in potato plant was carried out by transient gene expression of constructs with agro-infiltration followed by mechanical viral infection. Results showed that successful production of siRNAs confer resistance to two PVY strain. Comparison between transiently expressed constructs indicated that applying CP+UR PVY hairpin RNA was the most efficient RNAi construct to confer resistance. Resistance was found to have taken the form of immunity, since no viral particle could be detected in the upper leaves as shown by ELISA assay and Northern hybridizations. To the best of our knowledge, this is the first report on the application of 3'non-coding region of PVY in conferring complete resistance against virus in potato.