GALLUSCI Philippe

Nationalité : France
Contact : philippe.gallusci@inrae.fr / philippe.gallusci@u-bordeaux.fr

Domaine de Recherche

Our research group is currently investigating the regulatory functions of epigenetic mechanisms in plants.
The concept of epigenetic refers to changes in chromatin organization, which often lead to modifications in gene expression without change in the underlying genomic DNA sequence of the organism. Epigenetic information is based on DNA methylations and histone post-translational modifications that determine the state of chromatin structure and regulate the transcriptionally active or inert state of DNA. These epigenetic marks are heritable through DNA replication and cell propagation therefore determining cell lineage during development.

Our project aims at deciphering the functional relevance of epigenetic regulatory processes in the context of plant development using tomato and grape as model systems, with a special interest in fruit development. We have now shown that Polycomb proteins, involved in gene repression following histone methylation, impact multiple aspects of tomato plant development including leaf and plant shape and fruit ripening. In addition, DNA methylation appears to be essential both to tomato plant growth and to fruit development. Plants with reduced methylation levels and those impaired in DNA demethylation processes present several phenotypic alterations including modified leaf shape, altered flower development and dramatic alteration of fruit ripening. Fruit ripening phenotypes were associated with changes in gene expression and methylation levels. Transcriptomes, metabolomes and methylomes of fruits impaired in demethylation are currently under study to determine the network of genes controlled by methylation/demethylation in fruits. So far the results obtained are the foundation of a new paradigm where epigenetic regulatory pathways are central to the regulation of tomato fruit ripening and are consistent with genomic methylation being crucial to the regulation of tomato plant development.
Our recent results also suggest an involvement of DNA methylation in grape berry development and developing functional biology approaches to determine the underlying molecular mechanisms. In addition, we are now investigating the functions of DNA methylation and histones marks during the grafting process in tomato and grape and analyzing the relevance of these mechanisms in the response of grape plant and fruit to environmental constraints.