Proanthocyanidin-accumulating cells in Arabidopsis testa: regulation of differentiation and role in seed development.
Anthocyanidin reductase encoded by the BANYULS (BAN) gene is the core enzyme in proanthocyanidin (PA) biosynthesis. Here, we analyzed the developmental mechanisms that regulate the spatiotemporal expression of BAN in the developing Arabidopsis seed coat. PA-accumulating cells were localized histochemically in the inner integument (seed body and micropyle) and pigment strand (chalaza). BAN promoter activity was detected specifically in these cells. Gain-of-function experiments showed that an 86-bp promoter fragment functioned as an enhancer specific for PA-accumulating cells. Mutations in regulatory genes of PA biosynthesis abolished BAN promoter activity (transparent testa2 [tt2], tt8, and transparent testa glabra1 [ttg1]), modified its spatial pattern (tt1 and tt16), or had no influence (ttg2), thus revealing complex regulatory interactions at several developmental levels. Genetic ablation of PA-accumulating cells targeted by the BAN promoter fused to BARNASE led to the formation of normal plants that produced viable yellow seeds. Importantly, these seeds had no obvious defects in endosperm and embryo development.
Debeaujon
Isabelle
I
Laboratoire de Biologie des Semences, Unité Mixte de Recherche, 204 Institut National de la Recherche Agronomique, Paris-Grignon, 78026 Versailles, France.
Nesi
Nathalie
N
Perez
Pascual
P
Devic
Martine
M
Grandjean
Olivier
O
Caboche
Michel
M
Lepiniec
Loïc
L
D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D026161:MADS Domain Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics / Q000378:metabolism; D044945:Proanthocyanidins / Q000096:biosynthesis* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D012639:Seeds / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid; D013634:Tannins / Q000096:biosynthesis*
D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D026161:MADS Domain Proteins; D044945:Proanthocyanidins; C470417:TT16 protein, Arabidopsis; C451324:TT2 protein, Arabidopsis; D013634:Tannins; C401411:BANYULS protein, Arabidopsis; D009247:NADH, NADPH Oxidoreductases