Visual detection of CaMV35S promoter via target-triggered rolling circle amplification of DNAzyme

The cauliflower mosaicvirus 355 (CaMV35S), as the most common promoter, has a usage rate of 70 % in transgenic crops, especially in dicots. Herein, a visual detection method of rolling circle amplification (RCA) combined with DNAzyme technology was developed for the determination of CaMV35S gene. A template sequence of the G-quadruple gene was designed for combining with the target gene CaMV35S. When the target gene existed, the RCA reaction occurred through the action of the enzyme, and the product combined with hemin to generate DNAzyme, which catalyzed the color reaction of 2'-hydrazine-bis-3-ethylbenzothiazolin-6-sulfonic acid (ARTS). Under the optimal experimental conditions, the linear range is 1 x 10(-13) similar to 1 x 10(-8) mol/L, and the detection limit is 3 x 10(-14) mol/L (S/N = 3). The method has been successfully applied to standard samples and practical samples (soybean and tofu). For verifying the feasibility and reliability, real-time fluorescent quantitative PCR method was used to detect the target gene CaMV35S, and the results were in good agreement with those of our method, indicating that our developed method can be used for the determination of actual samples.