Dynamic DNA-Methylation of Retrotransposons in Rue under Drought Stress

Ruta graveolens (rue) is plant native to the Mediterranean region and presents in traditional medicine of this region since ancient times. There is poor information about the genome of Ruta and repetitive sequences and active mobile genetic elements have not been identified yet. Since rue genome is still mostly unexplored, and proliferative capabilityand large size of transposons make them key contributors to genome size and evolution, we aimed to isolate and characterize transposon sequences with a view to better understanding rue genome. We have isolated novel types of Ty1-copia like LTR reverse transcriptase from Ruta graveolens, leading to investigation of the genomic organization and phylogenetic relationships. Since the activation of transposable elements in response to environmental changes represents a form of adaptive response to biotic stress, we investigated if drought stress could influence transposon methylation and if the extent of methylation has been related to expression level. The results can have implications for rue genome understanding and their potential impact on Ruta evolution.