We describe an Arabidopsis mutant, tso1, which develops callus-like tissues in place of floral organs. The tso1 floral meristem lacks properly organized three cell layers, and the nuclei of these cells are irregular in size and shape. Further analyses reveal partially formed cell walls and increased DNA ploidy in tso1 floral meristem cells, indicating defects in mitosis and cytokinesis. Our finding that TSO1 is required for organ formation in floral tissues but not in other tissues indicates that TSO1 may encode a floral-specific cell division component, or that TSO1 function is redundant in nonfloral tissues.

REFERENCES

Bowman
J. L.
,
Smyth
D. R.
,
Meyerowitz
E. M.
(
1991
)
Genetic interactions among floral homeotic genes of Arabidopsis.
Development
112
,
1
20
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
Drews
G. N.
,
Bowman
J. L.
,
Meyerowitz
E. M.
(
1991
)
Negative regulation of the Arabidopsis homeotic gene AGAMOUS by the APETALA2 product.
Cell
65
,
991
1002
Friedman
W. E.
(
1991
)
Double fertilization in Ephedra trifurca, a non-flowering seed plant: the relationship between fertilization events and the cell cycle.
Protoplasma
165
,
106
120
Gunning
B. E. S.
,
Wick
S. M.
(
1985
)
Preprophase bands, phragmoplasts and spatial control of cytokinesis.
J. Cell Sci. Suppl
2
,
157
179
Hagan
I.
,
Yanagida
M.
(
1990
)
Novel potential mitotic motor protein encoded by the fission yeast cut7 gene.
Nature
345
,
81
83
Irish
V. F.
,
Sussex
I. M.
(
1990
)
Function of the apetala-1 gene during Arabidopsis floral development.
Plant Cell
2
,
741
753
Jack
T.
,
Brockman.
L. L.
,
Meyerowitz
E. M.
(
1992
)
The homeotic gene APETALA3 of Arabidopsisthaliana encodes a MADS box and is expressed in petals and stamens.
Cell
68
,
683
697
Jurgens
G.
,
Mayer
U.
,
Rorres Ruiz
R. A.
,
Berleth
T.
,
Misera
S.
(
1991
)
Genetic analysis of pattern formation in the Arabidopsis embryo.
Development
1
,
27
38
Jurgens
M.
,
Hepler
L. H.
,
Rivers
B. A.
,
Hepler
P. K.
(
1994
)
BAPTA-calcium buffers modulate cell plate formation in stamen hairs of Tradescantia: evidence for calcium gradients.
Protoplasma
183
,
86
99
Konieczny
A.
,
Ausubel
F. M.
(
1993
)
A procedure for mapping Arabidopsis mutations using codominant ecotype-specific PCR-based markers.
Plant J
4
,
403
410
Lambert
A. M.
(
1993
)
Microtubule organizing centers in higher plants.
Curr. Opin. Cell Biol
5
,
116
122
Liu
C. M.
,
Johnson
S.
,
Wang
T. L.
(
1995
)
cyd, a mutant of pea that alters embryo morphology, is defective in cytokinesis.
Dev. Genet
16
,
321
331
Liu
Z.
,
Meyerowitz
E. M.
(
1995
)
LEUNIG regulates AGAMOUS expression in Arabidopsis flowers.
Development
121
,
975
991
Paul
D. C.
,
Goff
C. H. W.
(
1973
)
Comparative effects of caffeine, its analogues and calcium deficiency on cytokinesis.
Exp. Cell Res
78
,
399
413
Pickett-Heaps
J. D.
,
Northcote
D. H.
(
1966
)
Organization of microtubules and endoplasmic reticulum during mitosis and cytokinesis in wheat meristems.
J. Cell Sci
1
,
109
120
Poethig
S.
(
1989
)
Genetic mosaic and cell lineage analysis in plants.
Trends Genet
5
,
273
277
Rappaport
R.
(
1986
)
Establishment of the mechanism of cytokinesis in animal cells.
Int. Rev. Cytol
105
,
245
281
Sakai
H.
,
Medrano
L. J.
,
Meyerowitz
E. M.
(
1995
)
Role of SUPERMAN in maintaining Arabidopsis floral whorl boundaries.
Nature
378
,
199
203
Samejima
I.
,
Matsumoto
T.
,
Nakaseko
Y.
,
Beach
D.
,
Yanagida
M.
(
1993
)
Identification of seven new cut genes involved in Schizosaccharomyces pombe mitosis.
J. Cell Sci
105
,
135
143
Smyth
D. R.
,
Bowman
J. L.
,
Meyerowitz
E. M.
(
1990
)
Early flower development in Arabidopsis.
Plant Cell
2
,
755
767
Torres-Ruiz
R. A.
,
Jurgens
G.
(
1994
)
Mutations in the fass gene uncouple pattern formation and morphogenesis in Arabidopsis development.
Development
120
,
2967
2978
Traas
J.
,
Bellini
C.
,
Nacry
P.
,
Kronenberger
J.
,
Bouchez
D.
,
Caboche
M.
(
1995
)
Normal differentiation patterns in plants lacking microtubular preprophase bands.
Nature
375
,
676
677
Uzawa
S.
,
Samejima
I.
,
Hirano
T.
,
Tanaka
K.
,
Yanagida
M.
(
1990
)
The fission yeast cut1 +gene regulates spindle pole body duplication and has homology to the budding yeast ESP1 gene.
Cell
62
,
913
925
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.
,
Meyerowitz
E.M.
(
1994
)
The ABCs of floral homeotic genes.
Cell
78
,
203
209
Yanofsky
M. F.
,
Ma
H.
,
Bowman
J. L.
,
Drews
G. N.
,
Feldmann
K. A.
,
Meyerowitz
E. M.
(
1990
)
The protein encoded by the Arabidopsis homeotic gene AGAMOUS resembles transcription factors.
Nature
346
,
35
40
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