Epigenetic analysis of wild tomato species

Tomato (Solanum lycopersicum) which forms a small monophyletic clade within the large Solanaceae family has been chosen as a model system for studying the Solanaceae genome, as well as fruit development and ripening, and crop domestication. Though many efforts have been devoted to the analysis of the genetic diversity of tomato species, little work has focused on the epigenetic diversity in this clade, although there is a general agreement that epigenetic processes play essential role in the phenotypic diversity in animal and plant system. The present project is aimed at analyzing the epigenetic diversity in a subset of wild tomato species. The Solanum lycopersicum clade presents a favorable situation for such a study as it is constituted of diploid plants sharing a high degree of genomic syntheny. This study was focused on tomato Polycomb group genes of the Enhancer of Zeste family, which consists in three genes (SlEZ1, SlEZ2, SlEZ3). SlEZ1 and SlEZ2 genes were previously shown to be involved in the control of fruit and flower development of the domesticated tomato (How Kit A et al, 2010), whereas the role SlEZ3 remains unknown. Our analysis includes the comparative analysis of SlE(Z) gene sequences, as well as the study of their expression during tomato fruit development. Interestingly the analysis of SlEZ2 gene in red-fruited species compared to green-fruited species revealed major differences in fruit DNA methylation and fruit gene expression profiles. These differences were correlated with the presence of a retrotransposon in the SlEZ2 promoter region in red-fruited species specifically