Cloning and analysis of reverse transcriptases from Ty1-copia retrotransposons in Camellia sinensis

As mobile genetic elements, the diversity and activity of the Tyl-copia retrotransposons are key contributors to genome organisation and evolution, which have been investigated in many plants but little in the tea plant, Camellia sinensis. We selected a total of 12 varieties of tea plant distributed across a large geographical area and sequenced the reverse transcriptase (RT) sequences of Ty1-copia retrotransposons using degenerate primers. The sequences that were widespread among tea varieties, were approximately 260 bp in length and exhibited high heterogeneity among tea plants. The RT sequences from tea plants were similar to other known Ty1-copia retrotransposon RT sequences. Phylogenetic analysis showed that tea RT sequences were closely related to those from woody plants, such as pear, poplar and apple. In contrast, they were more distantly related to RT sequences from herbaceous plants, such as tomato and rice. Activity assay revealed that Ty1-copia retrotransposons are transcriptionally active during the normal development of tea plants. These results will support further research on Ty1-copia retrotransposons in C. sinensis.