Abstract: T0tal RNA was extracted with an impmvod one．step method from tobacco leaves infec ted with potato
virus X (P、Ⅸ )．The mole quality of tested RNA was very good，which indieated that the impmvod method was
very efective and simple． A pair of specific primers were designed an d synthesized based on the homologous
nueleotide sequence of diferent isolates of PVX by the reverse transcription an d polymerase chain reaction (RT．
PCR)，a 308 bp DNA fragment was amplified successfully from PVX of Shandong isolate，and no fragment was
obtained from contro1．With only 1U Reverse Transefiptase XL (AMV)，the am plified resnlt were still very good．
The resnlts showed that an economical an d convenient RT．PCR detec tion system of Pvx was set up．

Key words: ：Pvx (Pomto vires X), Vires, Detection, Reverse transcription and polymemse chain reaction(RT．PCR)