Abstract: Different types of reverse transcriptase（RT）sequences in the whole genome of Pyrus pyrifolia white pear group‘Suli’were predicted by bioinformatics methods. A total of 345 RT sequences were obtained from copia group and 99 RT sequences were from gypsy group. The cluster analysis indicated that there were six lineages（Ivana，Ale，TAR，Angela，Maximus and Bianca）in copia group and five lineages in gypsy group（Athila，Tat，CRM，Reina and Tekay）. Sequence alignment showed a high heterogeneity in both copia group and gypsy group，and the divergence of RT in both groups was 0.44 and 0.38，respectively. Eight types of RT were selected to design primers，each pair of primers showed clear amplified bands by PCR using genomic DNA of other Pyrus species. Eight types of RT were expressed with different levels in leaves，seeds and fruits of‘Wonhwang’pear，which was the first report on the expression of RT in the organs of pear trees under normal growing condition.

Key words: Pyrus, Ty1-copia, Ty3-gypsy, reverse transcriptase, prediction