title: The AUXIN RESPONSE FACTOR 2 gene of Arabidopsis links auxin signalling, cell division, and the size of seeds and other organs.
abstract: Control of seed size involves complex interactions among the zygotic embryo and endosperm, the maternally derived seed coat, and the parent plant. Here we describe a mutant in Arabidopsis, megaintegumenta (mnt), in which seed size and weight are dramatically increased. One factor in this is extra cell division in the integuments surrounding mnt mutant ovules, leading to the formation of enlarged seed coats. Unusually for integument mutants, mnt does not impair female fertility. The mnt lesion also has pleiotropic effects on vegetative and floral development, causing extra cell division and expansion in many organs. mnt was identified as a mutant allele of AUXIN RESPONSE FACTOR 2 (ARF2), a member of a family of transcription factors that mediate gene expression in response to auxin. The mutant phenotype and gene expression studies described here provide evidence that MNT/ARF2 is a repressor of cell division and organ growth. The mutant phenotype also illustrates the importance of growth of the ovule before fertilization in determining final size of the seed.
authors.affiliation: Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK.
authors.forename: Marie C
authors.initials: MC
authors.lastname: Schruff
authors.forename: Melissa
authors.initials: M
authors.lastname: Spielman
authors.forename: Sushma
authors.initials: S
authors.lastname: Tiwari
authors.forename: Sally
authors.initials: S
authors.lastname: Adams
authors.forename: Nick
authors.initials: N
authors.lastname: Fenby
authors.forename: Rod J
authors.initials: RJ
authors.lastname: Scott
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics*; D001483:Base Sequence; D002455:Cell Division; D018744:DNA, Plant / Q000235:genetics; D035264:Flowers / Q000254:growth & development; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D007210:Indoleacetic Acids / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D030821:Plants, Genetically Modified; D012097:Repressor Proteins / Q000235:genetics*; D012639:Seeds / Q000254:growth & development; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics
chemical_list: C503421:ARF2 protein, Arabidopsis; D029681:Arabidopsis Proteins; D018744:DNA, Plant; D007210:Indoleacetic Acids; D012097:Repressor Proteins; D014157:Transcription Factors