Abstract: To assess genetic diversity and to authenticate the medicinal materials of Codonopsis pilosula(Franch.) Nannf. the present work including DNA isolation, optimization of PCR assay of inter-simple sequence repeat (ISSR) and primers screening were investigated. Among three DNA isolation methods, improved CTAB, improved SDS and isolation kit, the improved CTAB was found to be the best. Based on priority selection design and those results in reported references, the optimal ISSRPCR action was carried out in a volume of 50 μL containing 20 ng of genomic DNA, 1.25 U of Taq polymerase, 1×buffer, 200 μmol·L^-1 each of dATP, dGTP, dCTP and dTTP, 0.5 μmol·L^-1 of primer, and 2.25 μmol·L^-1 Mg²⁺. According to this PCR system, thirteen of one hundred primers were chosen for their clarity, high polymorphism and repeatition.

Key words: Codonopsis pilosula, DNA isolation, optimization of ISSR-PCR system, primer screening