Abstract: A multiplex real-time polymerase chain reaction (PCR) method for simultaneous and rapid detection of components derived from sweet potato, cassava, potato, and corn was established. The g3pdhs gene of sweet potato and cassava, the UGPase gene of potato and the zSSIIb gene of corn were used as target genes to design specific primers and TaqMan probe, and the 18S rRNA gene was used as the internal reference gene. Methodological validation was performed, and the proposed method was applied to simulated samples with different mixing ratios and actual starch samples. The results showed that this method was high-throughput, sensitive and specific. No cross-reaction was found with 15 non-target sources. The detection sensitivity for template DNA was 3 × 10-3 ng/μL, and the proposed method had a good linear relationship and high amplification efficiency. The detection limit for edible starch samples was 0.1%. The results of the PCR method for 50 actual samples were consistent with those of the reference method, indicating that this method could be used for the detection of common adulterants in edible starches.

Key words: multiplex real-time polymerase chain reaction; edible starch; cassava; sweet potato; potato; corn