RESUMO
<p><b>OBJECTIVE</b>In this study, orthogonal design was used to optinize DDRT-PCR amplification system on Pinellia ternata microtubers in vitro in five factors four levels respectively.</p><p><b>METHOD</b>P. ternata stems and microtubers in vitro were selected as explants. The effects of five kinds of factors were studied by orthogonal design method including emplate cDNA, Mg2+, dNTPs, primers and Taq DNA polymerase, and in order to establish the optimum DDRT-PCR system of P. ternata microtubers in vitro.</p><p><b>RESULT AND CONCLUSION</b>A satisfactory DDRT-PCR technique system for P. ternata microtubers in vitro with desirable repeatability and polymorphic bands was established. In a total volume of 20 microL DDRT-PCR system, it contained 10 x buffer, 150 micromol L(-1) dNTPs, 2 micromol L(-1) anchor primer, 1 micromol L(-1) arbitrary primer, 2.5 mmol L(-1) Mg2+, 0.6 U Taq DNA polymerase and 2.5 microg template cDNA. The effect of the five factors was in sequence of Taq DNA polymerase > template cDNA > dNTPs > Mg2+ > Primers. The optimum DDRT-PCR system will provide scientific reference basis for studying effecting character of P. ternata microtubers associated with genes expression.</p>