Abstract: Using degenerate oligoncleotide primers corresponding to conserved domains of the Ty3-gypsy-like retrotransposon reverse transcriptase，a fragment of 430 bp was amplified by PCR from the genomic DNA of tree peony（Paeonia suffruticosa Andrews‘Luoyang Hong’）and Paeonia qiui. The amplicons were recovered and cloned into pMD-18T vector after purification，positive clones were selected and identified by colony PCR，then sequenced and analyzed. Thirteen different sequences of reverse transcriptase from tree peony‘Luoyang Hong’and Paeonia qiui were obtained and six clusters were identified with high heterogeneity through phylogenic analysis after alignment analyses of their nucleotide sequences. These sequences showed high heterogeneity，mainly characterized by deletion mutations. The length of the nucleotide sequences varied from 412 to 446 bp，and homology ranged from 71.5% to 94.8%. When translated into amino acids，twelve sequences presented stop codon mutation，and three sequences presented frameshift mutation. A phylogenic tree was constructed based on the amino acid sequences from other species，indicating that horizontal transmission of retrotransposon has occurred among the plants in the past.

Key words: tree peony, Ty3-gypsy-like retrotransposons, reverse transcriptase, heterogeneity