RNA-Mediated Virus Resistance In Transgenic Potato

Potato virus Y (PVY) is a main virus to potato causing severe gricultural loss and seed degeneration. RNA-mediated plant virus resistance, which shows more effective and biosafe, is a powerful strategy in breeding virus resistance plant including potato. In this strategy coat protein gene of viruses were widely used.In this research, virus resistance potato plants transformed with PVY Coat Protein (CP) gene. were produced by improved agrobacterium mediated transformation system of potato. Analysis at molecular level and virus assay were done to the transgenic plants. The main results are as follow:Factors influencing plants regeneration from explant were nvestigated.Results showed that potato leaf as explant was induced callus with high frequency which increased by 70% on medium containing GA3 10mg/L and 6-BA 4.5 mg/L compared to control. It was found that Kanamycin concentration 60mg/L was proper for potato varieties T and L, 40 mg/L for variety 203 in identifying the sensitivity of explant, but 40 mg/L for T and L, 20 mg/L for 203 in root-produce medium to select transformed plants.High transformation frequency was reached when explants pre-cultured for 4 days were immersed into agrobacterium with concentration 4.24~108 cells/L for 12 minutes for varieties T and L, 8 minutes for 203, and then co-cultured for 4 days.Transgenic plants were obtained including 5 for T, 4 for L. PCR results showed untranslatable PVY-CP gene was integrated into potato genome. Transgenic potato plants 1M, 2M, 3M, 5M, 10M, llM provided by laboratory were analyzed by Southern blot and Northern blot. Results showed that potato genome contained CP gene, and CP gene was expressed at RNA level, but RNA accumulation level differed among these transgenic lants.Virus resistance assay in greenhouse showed 3 plants had resistance toPVY, other 3 plants were susceptive condition showed that the resistance to PVY. And the assay at natural of 1M was between resistant and susceptive, other plants had the similar result.. Analyzing all the results, obviously there were an obverse relation between copy number of transgene and resistance that the transgenic potato plants had more than 2 transgenes (2M , 3M, 11 M) were resistant to PVY, nd a reverse relation between RNA accumulation level and resistance that RNA accumulation level of high resistance transgenic plants (2M , 3M, 11M) were lower than that of susceptive plants(1M, 5M, 10M).