Characterization of copia-like Retrotransposons in Pear

Abstract

Fifty-one non-redundant fragments of copia-like retrotransposons were cloned and identified in pear. Based on phylogenetic analysis, the retroelements were classified into 15 distinct groups and were highly heterogeneous in the pear genome. However, most of the groups could be clustered with some registered copia-like retrotransposons. Several clones showed relatively low identities to the known sequences. A Southern blot analysis, using 8 representative clones as probes, demonstrated that these retroelements were distributed in Pyrus species. Polymorphisms were detected among as well as within the Pyrus species, suggesting that the transposition of retrotransposons took place during evolution leading to diversification. Based on the Southern blot analysis, the copy number of copia-like retrotransposons was estimated to be at least 1, 000 in pear genomes.