GIGANTEA: a circadian clock‐controlled gene that regulates photoperiodic flowering in Arabidopsis and encodes a protein with several possible membrane‐spanning domains

Flowering of Arabidopsis is promoted by long days and delayed by short days. Mutations in the GIGANTEA (GI) gene delay flowering under long days but have little or no effect under short days. We have now isolated the GI gene and show that it encodes a novel, putative membrane protein. By comparing the sequence of the Arabidopsis gene with that of a likely rice orthologue and by sequencing mutant alleles, we identify regions of the GI protein that are likely to be important for its function. We show that GI expression is regulated by the circadian clock with a peak in transcript levels 8–10 h after dawn. The timing, height and duration of this peak are influenced by daylength. We analysed the interactions between GI and the LHY, CCA1 and ELF3 genes, previously shown to affect daylength responses; we show that the rhythmic pattern of GI expression is altered in the elf3, CCA1‐OX and lhy genotypes, and that CCA1 and LHY expression are reduced by gi mutations. Our results are consistent with the idea that GI plays an important role in regulating the expression of flowering time genes during the promotion of flowering by photoperiod.

[1]  D. E. Somers,et al.  The short-period mutant, toc1-1, alters circadian clock regulation of multiple outputs throughout development in Arabidopsis thaliana. , 1998, Development.

[2]  G von Heijne,et al.  Membrane protein structure prediction. Hydrophobicity analysis and the positive-inside rule. , 1992, Journal of molecular biology.

[3]  R. Croy.  Plant Molecular Biology Labfax , 1993 .

[4]  G. Rédei.  Supervital Mutants of Arabidopsis. , 1962, Genetics.

[5]  E. Tobin,et al.  Loss of the circadian clock-associated protein 1 in Arabidopsis results in altered clock-regulated gene expression. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[6]  Zhi-Yong Wang,et al.  Constitutive Expression of the CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) Gene Disrupts Circadian Rhythms and Suppresses Its Own Expression , 1998, Cell.

[7]  Rüdiger Simon,et al.  Activation of floral meristem identity genes in Arabidopsis , 1996, Nature.

[8]  J. Benson.  Abuse and HIV-related risk. , 1995, Focus.

[9]  K. Hicks,et al.  The Arabidopsis ELF3 gene regulates vegetative photomorphogenesis and the photoperiodic induction of flowering. , 1996, The Plant journal : for cell and molecular biology.

[10]  T. Mockler,et al.  Regulation of flowering time by Arabidopsis photoreceptors. , 1998, Science.

[11]  R. Amasino,et al.  Isolation of LUMINIDEPENDENS: a gene involved in the control of flowering time in Arabidopsis. , 1994, The Plant cell.

[12]  G. Coupland,et al.  The control of flowering time and floral identity in Arabidopsis. , 1998, Plant physiology.

[13]  P. Mullineaux,et al.  Plant transformation and expression vectors , 1993 .

[14]  D. Inzé,et al.  Oxidative stress tolerance and longevity in Arabidopsis: the late-flowering mutant gigantea is tolerant to paraquat. , 1998, The Plant journal : for cell and molecular biology.

[15]  Frans,et al.  Genes Galore: A Summary of Methods for Accessing Results from Large-Scale Partial Sequencing of Anonymous Arabidopsis cDNA Clones , 1994, Plant physiology.

[16]  J. Heslop-Harrison,et al.  The Transition to Flowering , 1964, Nature.

[17]  A. Peeters,et al.  GENETIC CONTROL OF FLOWERING TIME IN ARABIDOPSIS. , 1998, Annual review of plant physiology and plant molecular biology.

[18]  M Koornneef,et al.  Genetic interactions among late-flowering mutants of Arabidopsis. , 1998, Genetics.

[19]  D. E. Somers,et al.  Conditional Circadian Dysfunction of the Arabidopsis early-flowering 3 Mutant , 1996, Science.

[20]  D. Blanchard,et al.  The electronic plant gene register , 1995, Plant physiology.

[21]  J. Putterill,et al.  T-DNA tagging of a flowering-time gene and improved gene transfer by in planta transformation of Arabidopsis , 1998 .

[22]  D. Voytas,et al.  The structure, distribution and evolution of the Ta1 retrotransposable element family of Arabidopsis thaliana. , 1990, Genetics.

[23]  S. Kay,et al.  Integration of circadian and phototransduction pathways in the network controlling CAB gene transcription in Arabidopsis. , 1996, Proceedings of the National Academy of Sciences of the United States of America.

[24]  D. Saunders.  Introduction to Biological Rhythms , 1977 .

[25]  M. Kanehisa,et al.  A knowledge base for predicting protein localization sites in eukaryotic cells , 1992, Genomics.

[26]  D Weigel,et al.  Flowering-time genes modulate the response to LEAFY activity. , 1998, Genetics.

[27]  R. Simon,et al.  The CONSTANS gene of arabidopsis promotes flowering and encodes a protein showing similarities to zinc finger transcription factors , 1995, Cell.

[28]  M. Rosbash,et al.  Circadian fluctuations of period protein immunoreactivity in the CNS and the visual system of Drosophila , 1990, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[29]  Jychian Chen,et al.  Monogenic Recessive Mutations Causing Both Late Floral Initiation and Excess Starch Accumulation in Arabidopsis. , 1995, The Plant cell.

[30]  M. Van Montagu,et al.  Sequence analysis of a 24‐kb contiguous genomic region at the Arabidopsis thaliana PFL locus on chromosome 1 1 , 1997, FEBS letters.

[31]  D. Weigel,et al.  LEAFY controls floral meristem identity in Arabidopsis , 1992, Cell.

[32]  M. Frohman,et al.  Rapid production of full-length cDNAs from rare transcripts: amplification using a single gene-specific oligonucleotide primer. , 1988, Proceedings of the National Academy of Sciences of the United States of America.

[33]  Joanna Putterill,et al.  The late elongated hypocotyl Mutation of Arabidopsis Disrupts Circadian Rhythms and the Photoperiodic Control of Flowering , 1998, Cell.

[34]  J. Dunlap.  Molecular Bases for Circadian Clocks , 1999, Cell.

[35]  Joseph R. Ecker,et al.  CTR1, a negative regulator of the ethylene response pathway in arabidopsis, encodes a member of the Raf family of protein kinases , 1993, Cell.

[36]  Y. Goldman,et al.  Wag the Tail: Structural Dynamics of Actomyosin , 1998, Cell.

[37]  M. L. Anderson,et al.  Phytochrome A null mutants of Arabidopsis display a wild-type phenotype in white light. , 1993, The Plant cell.

[38]  Y. Komeda,et al.  Analysis of the role of the late‐flowering locus, GI, in the flowering of Arabidopsis thaliana , 1993 .