It is often assumed that in plants, where the relative positions of cells are fixed by cell walls, division orientations are critical for the generation of organ shapes. However, an alternative perspective is that the generation of shape may be controlled at a regional level independently from the initial orientations of new cell walls. In support of this latter view, we describe here a recessive mutation of maize, tangled-1 (tan-1), that causes cells to divide in abnormal orientations throughout leaf development without altering overall leaf shape. In normal plants, leaf cells divide either transversely or longitudinally relative to the mother cell axis; transverse division are associated with leaf elongation and longitudinal divisions with leaf widening. In tan-l mutant leaves, cells in all tissue layers at a wide range of developmental stages divide transversely at normal frequencies, but longitudinal divisions are largely substituted by a variety of aberrantly oriented divisions in which the new cell wall is crooked or curved. Mutant leaves grow more slowly than normal, but their overall shapes are normal at all stages of their growth. These observations demonstrate that the generation of maize leaf shape does not depend on the precise spatial control of cell division, and support the general view that mechanisms independent from the control of cell division orientations are involved in the generation of shape during plant development.

Reference

Reference
Barlow
P. W.
(
1991
)
From cell wall networks to algorithms: The simulation and cytology of cell division patterns in plants.
Protoplasma
162
,
69
85
Benfey
P. N.
,
Schiefelbein
J. W.
(
1994
)
Getting to the root of plant development: the genetics of Arabidopsis root formation.
Trends Genet
10
,
84
88
Berleth
T.
,
Jurgens
G.
(
1993
)
The role of the monopteros gene in organising the basal body region of the Arabidopsis embryo.
Development
118
,
575
587
Casero
P. J.
,
Casimiro
I.
,
Rodriguez-Gallardo
L.
,
Martin-Partido
G.
,
Lloret
P. G.
(
1993
)
Lateral root initiation by asymmetrical transverse divisions of pericycle cells in adventitious roots of Allium cepa.
Protoplasma
176
,
138
144
Costa
M.
,
Wilson
E. T.
,
Wieschaus
E.
(
1994
)
A putative cell signal encoded by the folded gastrulation gene coordinates cell shape changes during Drosophila gastrulation.
Cell
76
,
1075
1089
Foard
D. E.
(
1971
)
The initial protrusion of a leaf primordium can form without concurrent periclinal cell divisions.
Can. J. Bot
49
,
1601
1603
Foard
D. E.
,
Haber
A. H.
,
Fishman
T. N.
(
1965
)
Initiation of lateral root primordia without completion of mitosis and without cytokinesis in uniseriate pericycle.
Amer. J. Bot
52
,
580
590
Green
P. B.
(
1987
)
Inheritance of pattern: Analysis from phenotype to gene.
Amer. Zool
27
,
657
673
Gunning
B. E. S.
,
Hughes
J. E.
,
Hardham
A. R.
(
1978
)
Formative and proliferative cell divisions, cell differentiation, and developmental changes in the meristem of Azolla roots.
Planta
143
,
121
144
Haber
A. H.
(
1962
)
Nonessentiality of concurrent cell divisions for degree of polarization of leaf growth. I. Studies with radiation-induced mitotic inhibition.
Amer. J. Bot
49
,
583
589
Haber
A. H.
,
Foard
D. E.
(
1963
)
Nonessentiality of concurrent cell divisions for degree of polarization of leaf growth. II. Evidence from untreated plants and from chemically induced changes of the degree of polarization.
Amer. J. Bot
50
,
937
944
Hemerly
A.
,
de Almeida Engler
J.
,
Bergounioux
C.
,
Van Montagu
M.
,
Engler
G.
,
Inze
D.
,
Ferreira
P.
(
1995
)
Dominant negative mutants of the Cdc2 kinase uncouple cell division from iterative plant development.
EMBO J
14
,
3925
3936
Kaplan
D. R.
,
Hagemann
W.
(
1991
)
The relationship of cell and organism in vascular plants.
Bioscience
41
,
693
703
Kutschera
U.
(
1989
)
Tissue stresses in growing plant organs.
Physiol. Plant
77
,
157
163
Lloyd
C. W.
(
1991
)
How does the cytoskeleton read the laws of geometry in aligning the division plane of plant cells?.
Development
1
,
55
65
Mansfield
S. G.
,
Briarty
L. G.
(
1991
).
Early embryogenesis in Arabidopsis thaliana. II. The developing embryo.
Can. J. Bot
69
,
461
476
Mayer
U.
,
Buttner
G.
,
Jurgens
G.
(
1993
)
Apical-basal pattern formation in the Arabidopsis embryo: studies on the role of the gnom gene.
Development
117
,
149
162
McHale
N. A.
(
1993
)
LAM-1 and FAT genes control development of the leaf blade in Nicotiana sylvestris.
Plant Cell
5
,
1029
1038
Parks
S.
,
Wieschaus
E.
(
1991
)
The Drosophila gastrulation gene concertina encodes a Ga-like protein.
Cell
64
,
447
458
Poethig
R. S.
(
1987
)
Clonal analysis of cell lineage patterns in plant development.
Amer. J. Bot
74
,
581
594
Pollock
E. G.
,
Jensen
W. A.
(
1964
)
Cell development during early embryogenesis in Capsella and Gossypium.
Amer. J. Bot
51
,
915
921
Sharman
B. C.
(
1942
)
Developmental anatomy of the shoot of Zea mays L.
Ann. Bot
6
,
245
282
Sinha
N.
,
Hake
S.
,
Freeling
M.
(
1993
)
Genetic and molecular analysis of leaf development.
Curr. Top. Dev. Biol
28
,
47
80
Stewart
R. N.
,
Semeniuk
P.
,
Dermen
H.
(
1974
)
Competition and accommodation between apical layers and their derivatives in the ontogeny of chimeral shoots of Pelargoniumhortorum.
Amer. J. Bot
61
,
54
67
Stewart
R. N.
,
Dermen
H.
(
1975
)
Flexibility in ontogeny as shown by the contribution of the shoot apical layers to leaves of periclinal chimeras.
Amer. J. Bot
62
,
935
947
Sylvester
A. W.
,
Cande
W. Z.
,
Freeling
M.
(
1990
)
Division and differentiation during normal and liguleless-1 maize leaf development.
Development
110
,
985
1000
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
Wick
S. M.
(
1991
)
Spatial aspects of cytokinesis in plant cells.
Curr. Opin. Cell Biol
3
,
253
260
Young
P. E.
,
Richman
A. M.
,
Ketchum
A. S.
,
Kiehart
D. P.
(
1993
)
Morphogenesis in Drosophila requires nonmuscle myosin heavy chain function.
Genes Dev
7
,
29
41
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