The overall morphology of an Arabidopsis plant depends on the behaviour of its meristems. Meristems derived from the shoot apex can develop into either shoots or flowers. The distinction between these alternative fates requires separation between the function of floral meristem identity genes and the function of an antagonistic group of genes, which includes TERMINAL FLOWER 1. We show that the activities of these genes are restricted to separate domains of the shoot apex by different mechanisms. Meristem identity genes, such as LEAFY, APETALA 1 and CAULIFLOWER, prevent TERMINAL FLOWER 1 transcription in floral meristems on the apex periphery. TERMINAL FLOWER 1, in turn, can inhibit the activity of meristem identity genes at the centre of the shoot apex in two ways; first by delaying their upregulation, and second, by preventing the meristem from responding to LEAFY or APETALA 1. We suggest that the wild-type pattern of TERMINAL FLOWER 1 and floral meristem identity gene expression depends on the relative timing of their upregulation.
Reference
Alvarez
J.
, Guli
C. L.
, Yu
X.-H.
, Smyth
D. R.
(1992
) TERMINAL FLOWER: a gene affecting inflorescence development in Arabidopsis thaliana.
Plant J
2
, 103
–116
Blazquez
M. A.
, Soowal
L. N.
, Lee
I.
, Weigel
D.
(1997
) LEAFY expression and flower initiation in Arabidopsis.
Development
124
, 3835
–3844
Blazquez
M. A.
, Green
R.
, Nilsson
O.
, Sussman
M. R.
, Weigel
D.
(1998
) Gibberellins promote flowering of Arabidopsis by activating the LFY promoter.
Plant Cell
10
, 791
–800
Bowman
J. L.
, Alvarez
J.
, Weigel
D.
, Meyerowitz
E. M.
, Smyth
D. R.
(1993
) Control of flower development in Arabidopsis thaliana by APETALA1 and interacting genes.
Development
119
, 721
–743
Bradley
D.
, Carpenter
R.
, Copsey
L.
, Vincent
C.
, Rothstein
S.
, Coen
E.
(1996
) Control of inflorescence architecture in Antirrhinum.
Nature
379
, 791
–797
Bradley
D.
, Ratcliffe
O.
, Vincent
C.
, Carpenter
R.
, Coen
E.
(1997
) Inflorescence commitment and architecture in Arabidopsis.
Science
275
, 80
–83
Coen
E. S.
, Carpenter
R.
(1993
) The metamorphosis of flowers.
Plant Cell
5
, 1175
–1181
Coen
E. S.
, Nugent
J. M.
(1994
) The evolution of flowers and inflorescences.
Development
1994
, 107
–116
Green
P. B.
, Linstead
P.
(1990
) A procedure for SEM analysis of complex shoot structures applied to the inflorescence of snapdragon (Antirrhinum).
Protoplasma
158
, 33
–38
Gustafson-Brown
C.
, Savidge
B.
, Yanofsky
M. F.
(1994
) Regulation of the floral homeotic gene APETALA1.
Cell
76
, 131
–143
Hempel
F. D.
, Weigel
D.
, Mandel
M. A.
, Ditta
G.
, Zambryski
P. C.
, Feldman
L. J.
, Yanofsky
M. F.
(1997
) Floral determination and expression of floral regulatory genes in Arabidopsis.
Development
124
, 3845
–3853
Huala
E.
, Sussex
I. M.
(1992
) LEAFY interacts with floral homeotic genes to regulate Arabidopsis floral development.
Plant Cell
4
, 901
–913
Irish
V. F.
, Sussex
I. M.
(1990
) Function of the APETALA1 gene in Arabidopsis floral development.
Plant Cell
2
, 741
–753
Kempin
S. A.
, Savidge
B.
, Yanofsky
M. F.
(1995
) Molecular basis of the cauliflower phenotype in Arabidopsis.
Science
267
, 522
–525
Koornneef
M.
, Hanhart
C. J.
, van der Veen
J. H.
(1991
) A genetic and physiological analysis of late flowering mutants in Arabidopsis thaliana.
Mol. Gen. Genet
229
, 57
–66
Mandel
M. A.
, Gustafson-Brown
C.
, Savidge
B.
, Yanofsky
M. F.
(1992
) Molecular characterization of the Arabidopsis floral homeotic gene APETALA1.
Nature
360
, 273
–277
Mandel
M. A.
, Yanofsky
M. F.
(1995
) A gene triggering flower development in Arabidopsis.
Nature
377
, 522
–524
Nilsson
O.
, Lee
I.
, Blazquez
M. A.
, Weigel
D.
(1998
) Flowering time genes modulate the response to LEAFY activity.
Genetics
150
, 403
–410
Ohshima
S.
, Murata
M.
, Sakamoto
W.
, Ogura
Y.
, Motoyoshi
F.
(1997
) Cloning and analysis of the Arabidopsis gene TERMINAL FLOWER 1.
Mol. Gen. Genet
254
, 186
–194
Okamuro
J. K.
, den Boer
B. G. W.
, Jofuku
K. D.
(1993
) Regulation of Arabidopsis flower development.
Plant Cell
5
, 1183
–1193
Parcy
F.
, Nilsson
O.
, Busch
M. A.
, Lee
I.
, Weigel
D.
(1998
) A genetic framework for floral patterning.
Nature
395
, 561
–566
Pnueli
L.
, Carmel-Goren
L.
, Hareven
D.
, Gutfinger
T.
, Alvarez
J.
, Ganal
M.
, Zamir
D.
, Lifschitz
E.
(1998
) The SELF-PRUNING gene of tomato regulates vegetative to reproductive switching of sympodial meristems and is the ortholog of CEN and TFL1.
Development
125
, 1979
–1989
Poethig
R. S.
(1990
) Phase change and the regulation of shoot morphogenesis in plants.
Science
250
, 923
–929
Ratcliffe
O. J.
, Amaya
I.
, Vincent
C. A.
, Rothstein
S.
, Carpenter
R.
, Coen
E. S.
, Bradley
D. J.
(1998
) A common mechanism controls the life cycle and architecture of plants.
Development
125
, 1609
–1615
Ruiz-Garcia
L.
, Madueno
F.
, Wilkinson
M.
, Haughn
G.
, Salinas
J.
, Martinez-Zapater
J. M.
(1997
) Different roles of flowering time genes in the activation of floral initiation genes in Arabidopsis.
Plant Cell
9
, 1921
–1934
Schultz
E. A.
, Haughn
G. W.
(1991
) LEAFY, a homeotic gene that regulates inflorescence development in Arabidopsis.
Plant Cell
3
, 771
–781
Shannon
S.
, Meeks-Wagner
D. R.
(1991
) A mutation in the Arabidopsis TFL1 gene affects inflorescence meristem development.
Plant Cell
3
, 877
–892
Shannon
S.
, Meeks-Wagner
D. R.
(1993
) Genetic interactions that regulate inflorescence development in Arabidopsis.
Plant Cell
5
, 639
–655
Simon
R.
, Igeno
M. I.
, Coupland
G.
(1996
) Activation of floral meristem identity genes in Arabidopsis.
Nature
384
, 59
–62
Sussex
I. M.
(1989
) Developmental programming of the shoot meristem.
Cell
56
, 225
–229
Weigel
D.
, Alvarez
J.
, Smyth
D. R.
, Yanofsky
M. F.
, Meyerowitz
E. M.
(1992
) LEAFY controls floral meristem identity in Arabidopsis.
Cell
69
, 843
–859
Weigel
D.
, Nilsson
O.
(1995
) A developmental switch sufficient for flower initiation in diverse plants.
Nature
377
, 495
–500
This content is only available via PDF.
© 1999 by Company of Biologists
1999
-HUBSwebinar.jpg?versionId=4486)
(update)-InPreprints.png?versionId=4486)
