Abstract: ObjectivePCR assay was developed for event-specific detection of transgenic virus resistant papaya 55-1.MethodA developed Cetyl Trimethyl Ammonium Bromide(CTAB)method and Qiagen DNeasy plant mini kit were used to extract DNA from papaya seed and fruit.Specific primers for PCR detection of papaya 55-1 were designed to amplify endogenous papain gene sequence and external segments,35S-GUS and NOS-35S,and corresponding detection methods were developed.ResultsResults of PCR amplification of papain gene indicated that both the developed CTAB method and Qiagen DNeasy plant mini kit were useful for DNA extraction from papaya seed and fruit.Resultsof amplification of the external segments(35S-GUS and NOS-35S)indicated that the developed method was useful to detect the transgenic virus resistant papaya line 55-1,and the absolute and relative limit of detection(LOD)of the method got to 8.15×10^-2 ng and 0.14% respectively.ConclusionThe developed PCR method can detect transgenic virus resistant papaya 55-1 specially and detective sensitivity can satisfy the need of qualitative detection for genetically modified foods.