Abstract:
OBJECTIVE To identify Leonurus japonicus and Lagopsis supina by DNA barcoding and specific primers.
METHODS The NJ phylogenetic tree was constructed by amplification and sequencing of L. japonicus and L. supina based on ITS2 universal primes. Specific primers of L. japonicus and L. supina were designed according to ITS2 sequence, and their specificity, annealing temperature, amount of primer, amount of template, number of cycles and detection limit were investigated. The melting temperature(Tm) values of L. japonicus and L. supina were detected by SYBR green fluorescent quantitative PCR based on specific primers, and their detection limits were investigated. Authenticity of the collected samples was detected by conventional PCR and qPCR respectively.
RESULTS The NJ tree based on ITS2 showned that L. japonicus and L. supina were clustered together independently. The primers of L. japonicus and L. supina were all specific. The optimal annealing temperature, primer volume, template volume and cycle times were 65.2 ℃, 1.0 μL(10 mmol·L−1), 80 ng and 35 cycles, respectively. The detection limits of L. japonicus and L. supina were 4.0 ng·μL−1 and 40.0 ng·μL−1, respectively. The Tm values of L. japonicus and L. supina were 85.5−86.0 ℃ and 82.0−82.5 ℃, respectively, and their detection limits reached 1 pg·μL−1 based on specific primes combined with SYBR green fluorescent quantitative PCR.
CONCLUSION L. japonicus and L. supina can be distinguished by DNA barcode, specific primer and quantitative fluorescence PCR. The detection limit of SYBR green fluorescent quantitative PCR is much lower than that of ordinary PCR. This study provides a basis for the identification of L. japonicus and L. supina.