All ramets collected were carefully washed and stored at room temperature after drying over silica gel. Total DNA was extracted according to the modified CTAB-method (Terauchi 1991; Štorchováet al. 2000). A modified version of the PCR-RAPD procedure of Williams et al. (1990) was used in order to identify genets. Amplification reactions were carried out with six primers, OPA-8, OPA-10, OPA-20, OPB-3, OPB-8 and OPB-11 (Operon Technologies Inc., Alameda, CA, USA) for each sampled shoot. Each 25-µL reaction volume contained 17.5 µL DDW, 2.5 µL 10× PCR buffer, 0.5 µL dNTP (2.5 mm each), 0.5 U Taq DNA polymerase (TaKaRa Ex taq, TaKaRa Biomedicals, Oohtu, Japan), 10 pmol of a primer (Operon Technologies Inc.), and 50 ng sampled DNA. Amplification was performed with a programmable thermal cycler (RoboCycler GRADIENT 96, Stratagene, La Jolla, CA, USA). Each reaction was passed through one cycle of 3 min at 94 °C, and 45 cycles of 1 min at 94 °C, 1 min at 36 °C and 2 min at 72 °C. Amplification products were analysed by electrophoresis in 2% agarose gels with a 0.5× Tris-borate-EDTA (TBE) buffer system including ethidium bromide, and 100 bp DNA ladder marker (New England Biolabs, inc., Beverly, MA, USA) was used to determine sizes of the amplified DNA products. Each run of each gel included a positive control that included the sampled DNA obtained from a single genet and a negative control that did not include any sampled DNA in order to confirm accuracy and reproducibility of the RAPD technique. Gel images were recorded by using a CCD camera system (Densitograph AE-6905C, ATTO, Tokyo, Japan) and a gel image of each sample was compared with all other images of the samples on a computer screen. The six selected primers gave 36 polymorphic bands, which were then used for genet identification; pairs of ramets that differed in band patterns were considered to belong to different genets. Each of the selected primers could distinguish DNA sampled from four different genets. We conducted the analyses using all of the six primers for all samples.