title: SEEDSTICK is a master regulator of development and metabolism in the Arabidopsis seed coat.
abstract: The role of secondary metabolites in the determination of cell identity has been an area of particular interest over recent years, and studies strongly indicate a connection between cell fate and the regulation of enzymes involved in secondary metabolism. In Arabidopsis thaliana, the maternally derived seed coat plays pivotal roles in both the protection of the developing embryo and the first steps of germination. In this regard, a characteristic feature of seed coat development is the accumulation of proanthocyanidins (PAs - a class of phenylpropanoid metabolites) in the innermost layer of the seed coat. Our genome-wide transcriptomic analysis suggests that the ovule identity factor SEEDSTICK (STK) is involved in the regulation of several metabolic processes, providing a strong basis for a connection between cell fate determination, development and metabolism. Using phenotypic, genetic, biochemical and transcriptomic approaches, we have focused specifically on the role of STK in PA biosynthesis. Our results indicate that STK exerts its effect by direct regulation of the gene encoding BANYULS/ANTHOCYANIDIN REDUCTASE (BAN/ANR), which converts anthocyanidins into their corresponding 2,3-cis-flavan-3-ols. Our study also demonstrates that the levels of H3K9ac chromatin modification directly correlate with the active state of BAN in an STK-dependent way. This is consistent with the idea that MADS-domain proteins control the expression of their target genes through the modification of chromatin states. STK might thus recruit or regulate histone modifying factors to control their activity. In addition, we show that STK is able to regulate other BAN regulators. Our study demonstrates for the first time how a floral homeotic gene controls tissue identity through the regulation of a wide range of processes including the accumulation of secondary metabolites.
authors.affiliation: Dipartimento di BioScienze, Università degli Studi di Milano, Milan, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Mizzotti
authors.affiliation: Dipartimento di BioScienze, Università degli Studi di Milano, Milan, Italy; Consiglio Nazionale delle Ricerche, Istituto di Biofisica, Milan, Italy.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Ezquer
authors.affiliation: Dipartimento di BioScienze, Università degli Studi di Milano, Milan, Italy.
authors.forename: Dario
authors.initials: D
authors.lastname: Paolo
authors.affiliation: Centro de Biotecnología y Genómica de Plantas-UPM-INIA, ETSI Agrónomos, Universidad Politécnica de Madrid, Campus de Montegancedo, Madrid, Spain.
authors.forename: Paloma
authors.initials: P
authors.lastname: Rueda-Romero
authors.affiliation: Dipartimento di BioScienze, Università degli Studi di Milano, Milan, Italy.
authors.forename: Rosalinda Fiorella
authors.initials: RF
authors.lastname: Guerra
authors.affiliation: Dipartimento di BioScienze, Università degli Studi di Milano, Milan, Italy.
authors.forename: Raffaella
authors.initials: R
authors.lastname: Battaglia
authors.affiliation: Department of Plant Sciences, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Ilana
authors.initials: I
authors.lastname: Rogachev
authors.affiliation: Department of Plant Sciences, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Asaph
authors.initials: A
authors.lastname: Aharoni
authors.affiliation: Dipartimento di BioScienze, Università degli Studi di Milano, Milan, Italy.
authors.forename: Martin M
authors.initials: MM
authors.lastname: Kater
authors.affiliation: Dipartimento di BioScienze, Università degli Studi di Milano, Milan, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Caporali
authors.affiliation: Dipartimento di BioScienze, Università degli Studi di Milano, Milan, Italy; Consiglio Nazionale delle Ricerche, Istituto di Biofisica, Milan, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Colombo
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015870:Gene Expression; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D063990:Gene Ontology; D018525:Germination; D026161:MADS Domain Proteins / Q000502:physiology*; D053858:Metabolic Networks and Pathways; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics / Q000378:metabolism; D044945:Proanthocyanidins / Q000096:biosynthesis; D011401:Promoter Regions, Genetic; D012639:Seeds / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D026161:MADS Domain Proteins; D044945:Proanthocyanidins; C476012:SEEDSTICK protein, Arabidopsis; C401411:BANYULS protein, Arabidopsis; D009247:NADH, NADPH Oxidoreductases