title: INDEHISCENT and SPATULA interact to specify carpel and valve margin tissue and thus promote seed dispersal in Arabidopsis.
abstract: Structural organization of organs in multicellular organisms occurs through intricate patterning mechanisms that often involve complex interactions between transcription factors in regulatory networks. For example, INDEHISCENT (IND), a basic helix-loop-helix (bHLH) transcription factor, specifies formation of the narrow stripes of valve margin tissue, where Arabidopsis thaliana fruits open on maturity. Another bHLH transcription factor, SPATULA (SPT), is required for reproductive tissue development from carpel margins in the Arabidopsis gynoecium before fertilization. Previous studies have therefore assigned the function of SPT to early gynoecium stages and IND to later fruit stages of reproductive development. Here we report that these two transcription factors interact genetically and via protein-protein contact to mediate both gynoecium development and fruit opening. We show that IND directly and positively regulates the expression of SPT, and that spt mutants have partial defects in valve margin formation. Careful analysis of ind mutant gynoecia revealed slight defects in apical tissue formation, and combining mutations in IND and SPT dramatically enhanced both single-mutant phenotypes. Our data show that SPT and IND at least partially mediate their joint functions in gynoecium and fruit development by controlling auxin distribution and suggest that this occurs through cooperative binding to regulatory sequences in downstream target genes.
authors: Department of Crop Genetics, John Ines Centre, Norwich Research Park, Norwich, Norfolk NR4 7UH, United Kingdom.
authors: Thomas
authors: T
authors: Girin
authors: Teodora
authors: T
authors: Paicu
authors: Pauline
authors: P
authors: Stephenson
authors: Sara
authors: S
authors: Fuentes
authors: Evelyn
authors: E
authors: Körner
authors: Martin
authors: M
authors: O'Brien
authors: Karim
authors: K
authors: Sorefan
authors: Thomas A
authors: TA
authors: Wood
authors: Vicente
authors: V
authors: Balanzá
authors: Cristina
authors: C
authors: Ferrándiz
authors: David R
authors: DR
authors: Smyth
authors: Lars
authors: L
authors: Østergaard
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D035264:Flowers / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D005638:Fruit / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D007210:Indoleacetic Acids / Q000378:metabolism*; D009154:Mutation; D010641:Phenotype; D025941:Protein Interaction Mapping; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D012098:Reproduction / Q000502:physiology; D058614:Seed Dispersal / Q000502:physiology*; D012639:Seeds / Q000235:genetics / Q000254:growth & development / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D007210:Indoleacetic Acids; C484035:INDEHISCENT protein, Arabidopsis; C426006:SPT protein, Arabidopsis