[en] In order to obtain potato plants which could be resistant to multiple viruses ( viroid) simultaneous- ly，P25，HC-Pro，and Virp1 gene targeting PVX，PVY，and PSTVd proteins were cloned，respectively. Three types of amiRNAs targeting sequences encoding the silencing suppressor P25，HC-Pro and Virp1 were designed by using Ar- abidopsis thaliana miR159a as backbone. These three amiRNA sequences were connected by Overlapping PCR. The synthetic of P25，HC-Pro and Virp1 gene was inserted into the expression vector pCAMBIA1300-221 to form p1300-221-preamiR-P25-HCPro-Virp1，and the vector was verified by PCR and restriction enzyme digestion. Pre-a- miR-P25-HCPro-Virp1 was transformed into minituber of potato cultivar Favorita by Agrobacterium tumefaciens in- fection. 15 transformed plants were obtained through regenerating，pressure screening and differentiation. PCR re- sults showed that 10 of them were detected the same size fragment ( 729 bp) as the target gene. Further qRT-PCR t e s t i n g c o n f i r m e d t h a t a m i R - P 2 5 - H C P r o - V i r p 1 g e n e w a s e x p r e s s e d i n 1 0 t r a n s f o r m e d p l a n t s ，a n d t h e r e l a t i v e e x p r e s - sion was between 7. 68 - 21. 37. Inoculated the T0 transgenic plants with the mixture virus of PVX，PVY and PSTVd by friction into the leaves of the plants at the 6 - 8 leaf stage. The plant growth was observed after 20 days and the results showed that the control plants were severely susceptible，with symptoms such as short plants and mottled leaves，while the transformed plants did not show infection symptoms，and growth normally. There was no vi- rus detected by RT-PCR either. This indicated that the transfected amiR-P25-HCPro-Virp could be stably expressed in the transformed plants，and the transformed plants were resistant to PVX，PVY and PVSTd viruses ( viroid) . Transformed plants resistant to PVX，PVY and PVSTd were obtained，and the resistance was significant，which pro- vided new genetic resources for potato virus-resistant breeding.
