Résumé
The FLESHLESS somatic variation was identified in the grapevine as a chimeric phenotype that develops small fruits with a very little amount of flesh (Fernandez et al., 2006). The lack of flesh development was shown to result from the impairment of both cell division and expansion. Interestingly, the phenotype was found inheritable as a dominant trait, even some phenotypic reversions to the wild-type grapevine berry being observed in the original somatic variant and derived populations. Considering the interest of this phenotypic trait, several experimental approaches were performed to: i) decipher the causal genetic mechanism of the misregulation of the flesh morphogenesis due to flb mutation and ii) identify main genes associated with the fleshless phenotype as potential critical players of early fruit development in the grapevine. Fine mapping using DRCF (Dwarf, Rapid Cycling and Flowering) progenies (Chaib et al., 2010) and gene sequencing identified the insertion of an active MITEs (Miniature Inverted-repeat Transposable Elements) in the promoter of the PISTILLATA-like gene as the original event of the fleshless phenotypic variations. The TE insertion causes specific ectopic activation of a VvPI allele during early fruit development that maintains the expression of floral genes within the fruit. The analysis of transcriptomic patterns induced by the flb mutation into the fruit revealed a set of genes which expression is specific to the transition from flower to young berry development. Some of these genes were functionally characterised, in particular through DRCF genetic transformation. Main outputs of this work will be presented and discussed.