关键词: 樱桃, 中国樱桃, Ty1-copia, Ty3-gypsy, 反转录酶, 序列分析, 转录活性

Abstract: In order to provide fundamental clue for genetic evolution and variation mechanism，the reverse transcriptase gene fragments of Ty1-copia and Ty3-gypsy were isolated and sequenced using degenerate oligonucleotide primers from genomic DNA of Chinese cherry（Prunus pseudocerasus Lindl.）. And the transcriptional activity of retrotransposon were detected by reverse transcription polymerase chain reaction（RT-PCR）. The results showed that a total of 44 unique clones from Ty1-copia and 13 unique clones from Ty3-gypsy were obtained. Nucleotide sequence of Ty1-copia and Ty3-gypsy ranged in length from 262 to 269 bp and 414 to 435 bp，respectively. Alignment of nucleotide and amino acid sequences showed the high heterogeneity in LTR retrotransposon. Both Ty1-copia and Ty3-gypsy groups displayed mutation including premature stop codons，frameshift mutation and deletion. Phylogenetic analysis showed there were two lineages（TAR and Ale）in Ty1-copia group，and three lineages（Tat，Tekay，Reina）in Ty3-gypsy group. Furthermore，ratios of non-synonymous to synonymous（dN/dS）of Ty1-copia and Ty3-gypsy were less than 1，and Ty3-gypsy were greater than those of Ty1-copia，suggesting that they were evolving under a subfunctionalization model driven by purifying selection. Transcriptional activity was detected in 13 Ty1-copia and 7 Ty3-gypsy RT sequences and didn’t change as exposure to eight types of abiotic stresses. A Ty1-copia RT sequence named PpRT7 was highly transcriptionally activated by high temperature（42 ℃），and showed tissue specific expression.

Key words: Prunus pseudocerasus Lindl., Ty1-copia, Ty3-gypsy, reverse transcriptase, sequence analysis, transcriptional activity