Les séminaires ont lieu sur le Campus Montpellier SupAgro/INRA de La Gaillarde (2, place P. Viala Montpellier)
Jeudi 18 avril 2013
Salle 104 (Château) à 14h
Deciphering the regulatory network controlling flavonoid biosynthesis in Arabidopsis thaliana: from a simple idea to a real mess
BPMP, Equipe Nutrition Minérale et Stress Oxydatif
Flavonoids (proanthocyanidins or PAs, anthocyanins and flavonols) are secondary metabolites that play important roles in the interactions of plants with their environment. Moreover, these compound present valuable properties as antioxidants and colorants for foods, and as human health promoting factors (e.g. nutraceuticals, pharmaceuticals). In Arabidopsis, most of the mutants impaired in flavonoid accumulation were identified through the screenings for altered seed pigmentation that result in the transparent testa(tt) phenotype. The identification and molecular characterization of the ttloci has allowed decrypting the biosynthetic pathway that leads to flavonoid accumulation. Numerous studies indicate that the expression of the genes involved in the flavonoid biosynthetic pathway is controlled by distinct mechanisms in a tissue- or species-specific manner. This regulation involves different sets of transcriptional regulators that are specific to each class of flavonoid. On this line, it has been shown that the regulation of the PA and anthocyanin biosynthetic genes expression is controlled by the combined action of specific R2R3-MYB (subgroup 5 and 6) and R/B-like bHLH (subgroup IIIf) transcription factors together with the WD repeat protein TTG1, in a MYB-bHLH-WDR (MBW) ternary protein complex. However, by combining genetic, molecular and physiological approaches we found that the transcriptional regulatory network involved in the regulation of the flavonoid biosynthetic structural genes, and the activity of the MBW protein complex, is a bit more complicated and sometime counter intuitive. This is this work, that has been carried out over the past 5 years in my previous laboratory (Development and seed quality research group, IJPB, INRA Versailles), that will be the main focus of this presentation.
Contact : Christian Dubos