2.3. SSR-PCR amplification and detection
The PCR reaction mixtures contained 10 mM Tris–HCl (pH 8.3), 50 mM KCl, 50 ng genomic DNA, 10 pmol of each primer, 1.5 mM MgCl2, 0.2 mM of each dNTP, and 0.5 units of Taq DNA polymerase (Takara Bio Inc.). Amplification was performed in 20 μL volumes using Eppendorf Mastercycler (Eppendorf Scientific, Inc.) with an initial denaturation at 94 °C for 150 s followed by 34 cycles of 30 s at 94 °C, 30 s at the specific annealing temperature, 30 s at 72 °C and a final extension step of 10 min at 72 °C. Primers used in PCR were developed for the genus Cymbidium previously ( Huang et al., 2010) (Table 2). The PCR products were separated on 6% denaturing polyacrylamide gels and analyzed using the silver staining procedure (Brant et al., 1991).
Table 2.
Detailed information of the 13 EST-SSR markers used in analysis of genetic diversity of spring orchid