Résumé
We have been using genomics approaches with[i] Medicago truncatula[/i] as a tool to identify key genes determining seed yield and composition in [i]Medicago[/i] and in closely related legumes. Analyses of the proteome and transcriptome of the component tissues of the developing seed revealed extensive compartmentalization of gene expression and metabolic activities (Gallardo et al, 2007). Using a TF (Transcription Factor) qRT-PCR platform (Verdier et al., 2008) the Affymetrix Gene Chip (Benedito et al, 2008), and more recently, Nimblegen arrays (Buitink et al. submitted), putative regulatory genes specific for each seed tissue were identified, along with putative target genes of transcription factors (TFs). These genes have been located on the [i]M. truncatula[/i] genetic map and correlations between map positions of TF loci and QTLs for protein quantities and other seed phenotypes were detected. These correlations were confirmed in certain cases by the existence of similar QTLs at syntenic positions in pea. This approach has enabled us to attribute roles to two genes, both specifically expressed in the developing endosperm of [i]M. truncatula[/i] and present in pea. One encodes a DOF class transcription factor, whose mutant phenotype severely affects endosperm development. The second gene encodes an endosperm-specific subtilase (SBT1.1), which affects final seed weight in both species (D?Erfurth et al, 2012). The importance of the endosperm in determining legume seed size and composition will be discussed. The research leading to these results has received funding from the European Community FP7 grant agreements FP7 KBBE-613551, LEGATO, and FP7 KBBE-289562, ABSTRESS, from the ANR (QualityLegSeed and GenoPea), and from the Burgundy Regional Council.