Résumé
Grapevine varieties are composed of clones that derived by vegetation propagation from a same and unique seedling. It is expected that all clones are identical to their mother plant, however some can show variations in their morphological and agronomical traits due to somatic mutations. Retrotransposons, that are genetic entities able to insert new copies at different positions around the host genome, are known to be activated by biotic or abiotic stress. Grapevine is a perennial plant strongly stressed during a long productive growth –by grafting, pruning, pathogen attack, UV…- therefore retrotransposons may be able to play a role in the differentiation of clones belonging to the same variety. Three retrotransposons from the grapevine genome are described : GRET-1, Tvv1 and Vine-1. The main goal of this work consisted in evaluating by RT-PCR the level of expression of these three retrotransposons during development and under abiotic stress. To target each retrotransposon, two different specific domains were amplified, RT and gag domains. During shoot development, expression was only detected in roots and growing tissues such as flower buds, apical meristems and somatic embryos. Induction of retrotransposons transcription was evaluated under two abiotic stress. Depending of the retrotransposon family, a differential increase of expression was detected in UV exposed or wounded leaves, in general 6 or 12 hours after stress application. This result is the first evidence that grapevine retrotransposons are specifically expressed in undifferentiated tissues. Moreover, their expression is induced by stress conditions undergone by grapevine during its long productive growth and vegetative propagation. If the level of transposition is proportional to the level of transcription, we could believe that retrotransposons participate in clone differentiation.