For the genetic analysis of molecular mechanisms underlying temporal and spatial regulation of vascular pattern formation, we isolated mutants of Arabidopsis thaliana that are impaired in vascular patterning. Microscopic examination of the cotyledonary venation of 3,400 M(3) lines led to the identification of 12 mutant lines. Genetic analysis of 8 of these mutant lines indicated that vein pattern formation in these lines resulted from monogenic recessive mutations in 7 different genes, designated VAN1 through VAN7. Mutations in VAN1 through VAN6 genes caused fragmentation (disconnection or partial loss) of lateral veins of the cotyledon and tertiary veins of the rosette leaf whereas they were less injurious to the formation of major veins. Detailed characterization of the van3 mutant using pAthb8::GUS and pTED3::GUS, as molecular markers for the early stage of vascular tissue formation showed that the provascular tissue of the cotyledonary lateral veins was differentiated in fragments during late embryogenesis. These phenotypes of the van mutants are discussed in relation to the auxin signal flow canalization hypothesis and the diffusion-reaction prepattern hypothesis, with the fragility of the continuity in the minor vein formation favoring the latter hypothesis.

REFERENCES

REFERENCES
Asai
R.
,
Taguchi
E.
,
Kume
Y.
,
Saito
M.
,
Kondo
S.
(
1999
)
Zebrafish Leopard gene as a component of the putative reaction-diffusion system.
Mech. Dev
89
,
87
92
Baima
S.
,
Nobili
F.
,
Sessa
G.
,
Lucchetti
S.
,
Ruberti
I.
,
Morelli
G.
(
1995
)
The expression of the Athb-8 homeobox gene is restricted to provascualr cells in Arabidopsis thaliana.
Development
121
,
4171
4182
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
Busch
M.
,
Mayer
U.
,
Jurgens
G.
(
1996
)
Molecular analysis of the Arabidopsis pattern formation gene GNOM: gene structure and intragenic complementation.
Mol. Gen. Genet
250
,
681
691
Carland
F. M.
,
McHale
N. A.
(
1996
)
LOP1: a gene involved in auxin transport and vascular patterning in Arabidopsis.
Development
122
,
1811
1819
Carland
F. M.
,
Berg
B. L.
,
FitzGerald
J. N.
,
Jinamornphongs
S.
,
Nelson
T.
,
Keith
B.
(
1999
)
Genetic regulation of vascular tissue patterning in arabidopsis.
Plant Cell
11
,
2123
2137
Igarashi
M.
,
Demura
T.
,
Fukuda
H.
(
1998
)
Expression of the Zinnia TED3 promoter in developing tracheary elements of transgenic Arabidopsis.
Plant Mol. Biol
36
,
917
927
Jurgens
G.
,
Mayer
U.
,
Torres Ruiz
R. A.
,
Berleth
T.
,
Misera
S.
(
1991
)
Genetic analysis of pattern formation in the Arabidopsis embryo.
Development
1
,
27
38
Mattsson
J.
,
Sung
Z. R.
,
Berleth
T.
(
1999
)
Responses of plant vascular systems to auxin transport inhibition.
Development
126
,
2979
2991
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
Mayer
U.
,
Torres Ruiz
R. A.
,
Berleth
T.
,
Misera
S.
,
Jurgens
G.
(
1991
)
Mutations affecting body organization in the Arabidopsis embryo.
Nature
353
,
402
407
Meinhardt
H.
(
1995
)
Dynamics of stripe formation.
Nature
376
,
722
723
Nelson
T.
,
Dengler
N.
(
1997
)
Leaf vascular pattern formation.
Plant Cell
9
,
1121
1135
Przemeck
G. K. H.
,
Mattsson
J.
,
Hardtke
C. S.
,
Sung
Z. R.
,
Berleth
T.
(
1996
)
Studies on the role of the Arabidopsis gene MONOPTEROS in vascular development and plant cell axialization.
Planta
200
,
229
237
Sachs
T.
(
1968
)
The role of the root in the induction of xylem differentiation in peas.
Ann. Bot
32
,
391
399
Sachs
T.
(
1969
)
Polarity and the induction of organized vascular tissues.
Ann. Bot
33
,
263
275
Sachs
T.
(
1975
)
The control of the differentiation of vascular networks.
Ann. Bot
39
,
197
204
Sachs
T.
(
1991
)
Cell polarity and tissue patterning in plants.
Development
1
,
83
93
Shevell
D. E.
,
Leu
W. M.
,
Gillmor
C. S.
,
Xia
G.
,
Feldmann
K. A.
,
Chua
N. H.
(
1994
)
EMB30 is essential for normal cell division, cell expansion, and cell adhesion in Arabidopsis and encodes a protein that has similarity to Sec7.
Cell
77
,
1051
1062
Steinmann
T.
,
Geldner
N.
,
Grebe
M.
,
Mangold
S.
,
Jackson
C. L.
,
Paris
S.
,
Gälweiler
L.
,
Palme
K.
,
Jurgens
G.
(
1999
)
Coordinated polar localization of auxin efflux carrier PIN1 by GNOM ARF GEF.
Science
286
,
316
318
Torres Ruiz
R. A.
,
Jurgens
G.
(
1994
)
Mutations in the FASS gene uncouple pattern formation and morphogenesis in Arabidopsis development.
Development
120
,
2967
2978
Valvekens
D.
,
Van Montagu
M.
,
Van Lijsebettens
M.
(
1988
)
Agrobacterium tumefaciens -mediated transformation of Arabidopsis thaliana root explants by using kanamycin selection.
Proc. Natl. Acad. Sci. USA
85
,
5536
5540
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