Following the optimization of conventional PCR, the MgCl 2 concentration was balanced to 2.5 mM and the annealing temperature of 52°C was selected. Therefore the optimized conventional PCR reaction system could be summarized as follows: 1 × PCR buffer, 2.5 mmol/L MgCl 2 , 0.2 mmol/L dNTPs, 0.5 μmol/L each primers, 1.25 U Taq and 1 μL DNA template. The optimized annealing temperature was 52°C.