Isolation and characterization of repetitive DNA sequences from Panax ginseng

Repetitive sequences constitute a significant component of most eukaryotic genomes, and the isolation and characterization of repetitive DNA sequences provide an insight into the organization and evolution of the genome of interest. We report the isolation and characterization of the major classes of repetitive sequences from the genome of Panax ginseng. The isolation of repetitive DNA from P. ginseng was achieved by the reannealing of chemically hydrolyzed (200 bp 1 kb fragments) and heat-denatured genomic DNA to low Cot value. The low Cot fraction was cloned, and fifty-five P. ginseng clones were identified that contained repetitive sequences. Sequence analysis revealed that the fraction includes repetitive telomeric sequences, species-specific satellite sequences, chloroplast DNA fragments and sequences that are homologous to retrotransposons. Two of the retrotransposon-like sequences are homologous to Ty1/copia-type retroelements of Zea mays, and six cloned sequences are homologous to various regions of the del retrotransposon of Lilium henryi. The dol retrotransposon-like sequences and several novel repetitive DNA sequences from P. ginseng were used to differentiate P. ginseng from P. quinquefolius, and should be useful for evolutionary studies of these disjunct species.