A common mechanism controls the life cycle and architecture of plants.

The overall aerial architecture of flowering plants depends on a group of meristematic cells in the shoot apex. We demonstrate that the Arabidopsis TERMINAL FLOWER 1 gene has a unified effect on the rate of progression of the shoot apex through different developmental phases. In transgenic Arabidopsis plants which ectopically express TERMINAL FLOWER 1, both the vegetative and reproductive phases are greatly extended. As a consequence, these plants exhibit dramatic changes in their overall morphology, producing an enlarged vegetative rosette of leaves, followed by a highly branched inflorescence which eventually forms normal flowers. Activity of the floral meristem identity genes LEAFY and APETALA 1 is not directly inhibited by TERMINAL FLOWER 1, but their upregulation is markedly delayed compared to wild-type controls. These phenotypic and molecular effects complement those observed in the tfl1 mutant, where all phases are shortened. The results suggest that TERMINAL FLOWER 1 participates in a common mechanism underlying major shoot apical phase transitions, rather than there being unrelated mechanisms which regulate each specific transition during the life cycle.

[1]  G. Beer.  Embryos and ancestors , 1940 .

[2]  M. Mandel,et al.  A gene triggering flower formation in Arabidopsis , 1995, Nature.

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

[4]  E. Coen,et al.  Inflorescence Commitment and Architecture in Arabidopsis , 1997, Science.

[5]  G. Haughn,et al.  Genetic analysis of the floral initiation process (FLIP) in Arabidopsis , 1993 .

[6]  R. Poethig,et al.  Phase Change and the Regulation of Shoot Morphogenesis in Plants , 1990, Science.

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

[8]  J. Alvarez,et al.  terminal flower: a gene affecting inflorescence development in Arabidopsis thaliana , 1992 .

[9]  J. Ellis,et al.  In planta Agrobacterium mediated gene transfer by infiltration of adult Arabidopsis thaliana plants , 1993 .

[10]  E. Coen,et al.  floricaula: A homeotic gene required for flower development in antirrhinum majus , 1990, Cell.

[11]  Detlef Weigel,et al.  A developmental switch sufficient for flower initiation in diverse plants , 1995, Nature.

[12]  Elliot M. Meyerowitz,et al.  Control of flower development in Arabidopsis thaliana by APETALA1 and interacting genes , 1993 .

[13]  K. Hicks,et al.  Arabidopsisearly-flowering mutants reveal multiple levels of regulation in the vegetative-to-floral transition , 1996 .

[14]  Cindy Gustafson-Brown,et al.  Regulation of the arabidopsis floral homeotic gene APETALA1 , 1994, Cell.

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

[16]  D Weigel,et al.  LEAFY expression and flower initiation in Arabidopsis. , 1997, Development.

[17]  J. Bowman,et al.  Early flower development in Arabidopsis. , 1990, The Plant cell.

[18]  S. Shannon,et al.  A Mutation in the Arabidopsis TFL1 Gene Affects Inflorescence Meristem Development. , 1991, The Plant cell.

[19]  Cindy Gustafson-Brown,et al.  Molecular characterization of the Arabidopsis floral homeotic gene APETALA1 , 1992, Nature.

[20]  G. Stebbins,et al.  Flowering Plants. Evolution above the Species Level , 1977 .

[21]  J. Hayles,et al.  Cell Cycle Regulation in Yeast , 1986, Journal of Cell Science.

[22]  Y. Ogura,et al.  Cloning and molecular analysis of the Arabidopsis gene Terminal Flower 1 , 1997, Molecular and General Genetics MGG.

[23]  S. Shannon,et al.  Genetic Interactions That Regulate Inflorescence Development in Arabidopsis. , 1993, The Plant cell.

[24]  D. Weigel,et al.  Floral determination and expression of floral regulatory genes in Arabidopsis. , 1997, Development.

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

[26]  A. Ray,et al.  INTEGUMENT ( SIN 1 ) , a gene required for ovule development in Arabidopsis , also controls flowering time , 1996 .

[27]  Caroline Dean,et al.  The transition to flowering in Arabidopsis. , 1994 .

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

[29]  M. Van Montagu,et al.  Agrobacterium tumefaciens-mediated transformation of Arabidopsis thaliana root explants by using kanamycin selection. , 1988, Proceedings of the National Academy of Sciences of the United States of America.

[30]  S. Forsburg,et al.  Cell cycle regulation in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe. , 1991, Annual review of cell biology.

[31]  Steven Rothstein,et al.  Control of inflorescence architecture in Antirrhinum , 1996, Nature.

[32]  G. Haughn,et al.  LEAFY, a Homeotic Gene That Regulates Inflorescence Development in Arabidopsis. , 1991, The Plant cell.

[33]  F. Madueño,et al.  Different roles of flowering-time genes in the activation of floral initiation genes in Arabidopsis. , 1997, The Plant cell.