AGL24 acts as a promoter of flowering in Arabidopsis and is positively regulated by vernalization.

MADS-domain-containing transcription factors comprise a large family of regulators that have diverse roles in plant development, including the regulation of flowering time. AGAMOUS-LIKE 20/SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) and FRUITFUL act to promote flowering, whereas FLOWERING LOCUS C (FLC), FLOWERING LOCUS M/MADS AFFECTING FLOWERING1, and SHORT VEGETATIVE PHASE are inhibitors of flowering. Here we report that AGAMOUS-LIKE 24 (AGL24) also plays a role in the regulation of flowering time. agl24 mutants are late flowering and overexpression of AGL24 causes early flowering in wild-type and late-flowering-mutant backgrounds. The effect of AGL24 overexpression is most pronounced in autonomous-pathway-mutant and FRIGIDA-containing backgrounds. The behavior of AGL24 is most similar to that of SOC1. Like SOC1, AGL24 mRNA levels are upregulated by vernalization. Unlike SOC1, however, AGL24 mRNA levels are not affected by FLC, and therefore AGL24 may represent an FLC-independent target of the vernalization pathway. There is also evidence for cross-talk between AGL24 and SOC1. When overexpressed, SOC1 and AGL24 are able to upregulate each other's expression. Thus, AGL24 represents another component in a network of MADS-domain-containing transcription factors that regulate flowering time.

[1]  C. Dean,et al.  Arabidopsis, the Rosetta stone of flowering time? , 2002, Science.

[2]  R. Martienssen,et al.  The FRUITFULL MADS-box gene mediates cell differentiation during Arabidopsis fruit development. , 1998, Development.

[3]  R. Amasino,et al.  Loss of FLOWERING LOCUS C Activity Eliminates the Late-Flowering Phenotype of FRIGIDA and Autonomous Pathway Mutations but Not Responsiveness to Vernalization , 2001, Plant Cell.

[4]  Dean Ravenscroft,et al.  Antagonistic regulation of flowering‐time gene SOC1 by CONSTANS and FLC via separate promoter motifs , 2002, The EMBO journal.

[5]  H. Saedler,et al.  Knock-out mutants from an En-1 mutagenized Arabidopsis thaliana population generate phenylpropanoid biosynthesis phenotypes. , 1998, Proceedings of the National Academy of Sciences of the United States of America.

[6]  R. Amasino,et al.  Effect of Vernalization, Photoperiod, and Light Quality on the Flowering Phenotype of Arabidopsis Plants Containing the FRIGIDA Gene , 1995, Plant physiology.

[7]  J. Bowman,et al.  Negative regulation of the Arabidopsis homeotic gene AGAMOUS by the APETALA2 product , 1991, Cell.

[8]  F. Nagy,et al.  Identification of DNA sequences required for activity of the cauliflower mosaic virus 35S promoter , 1985, Nature.

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

[10]  R. Amasino,et al.  The late-flowering phenotype of FRIGIDA and mutations in LUMINIDEPENDENS is suppressed in the Landsberg erecta strain of Arabidopsis , 1994 .

[11]  J. S. Lee,et al.  The AGAMOUS-LIKE 20 MADS domain protein integrates floral inductive pathways in Arabidopsis. , 2000, Genes & development.

[12]  J. Riechmann,et al.  Regulation of flowering in Arabidopsis by an FLC homologue. , 2001, Plant physiology.

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

[14]  Y. Kobayashi,et al.  A pair of related genes with antagonistic roles in mediating flowering signals. , 1999, Science.

[15]  Hitoshi Onouchi,et al.  CONSTANS mediates between the circadian clock and the control of flowering in Arabidopsis , 2001, Nature.

[16]  W. Peacock,et al.  The FLF MADS Box Gene: A Repressor of Flowering in Arabidopsis Regulated by Vernalization and Methylation , 1999, Plant Cell.

[17]  R. Amasino,et al.  FLOWERING LOCUS C Encodes a Novel MADS Domain Protein That Acts as a Repressor of Flowering , 1999, Plant Cell.

[18]  R. Poethig,et al.  Phase change and the regulation of trichome distribution in Arabidopsis thaliana. , 1997, Development.

[19]  Z. Schwarz‐Sommer,et al.  Distinct roles of CONSTANS target genes in reproductive development of Arabidopsis. , 2000, Science.

[20]  R. Amasino,et al.  Memories of winter: vernalization and the competence to flower , 2000 .

[21]  J. Chory,et al.  Activation tagging of the floral inducer FT. , 1999, Science.

[22]  M. Koornneef,et al.  A genetic and physiological analysis of late flowering mutants in Arabidopsis thaliana , 1991, Molecular and General Genetics MGG.

[23]  R. Amasino,et al.  The gibberellic acid biosynthesis mutant ga1-3 of Arabidopsis thaliana is responsive to vernalization. , 1999, Developmental genetics.

[24]  R. Amasino,et al.  Identification of a MADS-box gene, FLOWERING LOCUS M, that represses flowering. , 2001, The Plant journal : for cell and molecular biology.

[25]  P. Huijser,et al.  Molecular cloning of SVP: a negative regulator of the floral transition in Arabidopsis. , 2000, The Plant journal : for cell and molecular biology.

[26]  E. Wisman,et al.  A MADS domain gene involved in the transition to flowering in Arabidopsis. , 2000, The Plant journal : for cell and molecular biology.