Isolation And Characterization Of Copia-like Reverse Transcriptase Sequences From Fritillaria Ussuriensis Maxim

Accumulated studies suggest that retrotransposons are ubiquitous in plants and may be the most abundant constituents of plant genomes. Sequence analysis of Copia-like retrotransposons from a wide range of plant taxa has revealed that there are highly conserved domains in the reverse transcriptases gene. In this study, a pair of degenerative oligonuleotide primers designed from conserved domains from encoded reverse transcriptases was used to amplify related sequences from Fritillaria ussuriensis Maxim. PCR fragments of roughly 240bp were isolated and cloned, 57 cloned were determined. According to alignment and phylogenetic analysis, the sequences were divided into 11 groups. The nucleotide sequence similarity shown by computer analysis between inter- and intra-group was in a wide range, which indicates high level of sequence heterogeneity among these clones and groups. Among these sequences, only 12 were intact, and others had a frameshift, a stop condon, or both. Southern blot analysis revealed distribution of these sequences in Fritillaria ussuriensis. Maxim. Methylation assay showed that these sequences are heavily methylated in the Fritillaria ussuriensis.Maxim genome.