doi: 10.1242/10.1242/dev.00196
The BLADE-ON-PETIOLE 1 gene controls leaf pattern formation through the modulation of meristematic activity in Arabidopsis
Chan Man Ha1,
Gyung-Tae Kim2,*,
Byung Chul Kim1,
Ji Hyung Jun1,
Moon Soo Soh1,
,
Yoshihisa Ueno3,
Yasunori Machida3,
Hirokazu Tsukaya2 and
Hong Gil Nam1,
1 Division of Molecular Life Science, Pohang University of Science and
Technology, San 31, Hyoja-dong, Pohang, Kyungbuk, 790-784, Korea
2 National Institute for Basic Biology/Center for Integrative Bioscience,
Myodaiji-cho, Okazaki 444-8585, Japan
3 Division of Biological Science, Graduate School of Science, Nagoya University,
Chikusa-ku, Nagoya 464-8602, Japan
* Present address: Department of Life Science and Resources, Dong-A University,
Hadan-2-dong 840, Busan, 604-714, Korea
Present address: Kumho Life and Environmental Science Laboratory, Oryong-dong,
Gwangju, 500-712, Korea
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Fig. 1. Phenotypes of bop1-1 mutant plants. (A) Gross morphologies of a
40-day-old wild-type (left) and a bop1-1 mutant (right) plant. (B)
Morphology of each rosette leaf of the wild-type (upper) compared with that of
bop1-1 mutant leaves (lower). The arrowheads in B indicate extended
petiole regions. (C) Morphology of bop1-1 (right) and wild-type
(left) cotyledons of 25-day-old plants. (D) Mature cauline leaf from a wild
type (left) and a bop1-1 mutant (right) plant. (E,F) Cotyledon (E),
and the first rosette leaf (F) of a 30-day-old bop1-1 plant showing
the original petiole region (OP) and the extended petiole region (EP;
arrowheads). (G) Fused rosette leaves from a bop1-1 mutant. Arrows
indicate two fused leaves. (H) Third leaves from a 37-day-old wild-type (left)
and a bop1-1 mutant (right) plant. (I) Flowers from the wild-type
(upper) and the bop1-1 mutant (lower). Bar in A, 10 mm.
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Fig. 3. Histological analysis of bop1-1 mutant plants. (A,C,E) Wild-type
leaf petioles. (B,D,F) bop1-1 mutant leaf petioles. The adaxial
surface is at the top. (A,B) Petioles of cotyledon. (C,D) Petioles of rosette
leaf. E and F are magnified views of C and D, respectively. Note that ectopic
outgrowths develop on the vasculature (B,D, arrowheads). Secondary outgrowths
are formed on the primary ectopic outgrowths (D, arrows). (G,H) Extended
petioles. The adaxial surface is at the top. (G) Extended cotyledonary
petiole. (H) Extended petiole of first rosette leaf. P, phloem cells; X, xylem
cells. Bars, 100 µm in (A-D,G,H), and 20 µm in (E,F).
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Fig. 2. Ectopic organ outgrowths on bop1-1 mutant plants. (A,C,E,I) Wild
type. (B,D,F-H,J) bop1-1 mutant. (A,B) Ten-day-old seedlings. One
leaf has been detached. Ectopic outgrowths are seen on the petioles of mutant
cotyledons (B, arrowheads). (C,D) Detached first leaves of 10-day-old
wild-type (C) and bop1-1 (D) seedlings. Adaxial side views. Arrows in
D indicate ectopic outgrowths at the base of the petiole of a mutant rosette
leaf. (E,F) Detached first leaves of 15-day-old wild-type (E) and mutant (F)
seedlings. Abaxial side views. Note the ectopic outgrowths on the petiole of
the mutant (F, arrowheads). (G,H) Detached third leaves of a 23-day-old mutant
plant. Note the development of numerous trichomes and leaf primordia on the
proximal region of the mutant leaf (H). (I,J) Cauline leaves of a mature
wild-type (I) and mutant (J) plant. The arrowheads in J represent ectopic
outgrowths on mutant plants. Bars, 100 µm (A-D,H), and 300 µm in the
remaining panels.
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Fig. 7. Development of ectopic outgrowths on the stems of the bop1-1
mutant. (A,C) Stem of mature wild-type plant. (B,D) Stem of mature
bop1-1 mutant plant. E and F are magnified views of C and D,
respectively. The arrows in C and D indicate developing trichomes and the
arrowheads in B and D indicate regions of ectopic outgrowths in the mutant. c,
cortex. Bars, 300 µm in (A,B), 100 µm in (C,D) and 20 µm in
(E,F).
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Fig. 4. Leaf venation pattern in bop1-1 mutant plants. (A,C) Cotyledons of
24-day-old wild type (A) and bop1-1 mutant (C). (B,D) First rosette
leaves of 16-day-old wild type (B) and bop1-1 mutant (D). Note that
the reticulate patterns of venation are distinct in the regions of ectopic
outgrowth on petioles of cotyledons and rosette leaves (C,D, arrows). Bars, 1
mm.
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Fig. 5. Origins of the defects in the bop1-1 mutant. (A-F,I,J) Cross
sections and (G,H) longitudinal sections of the shoot apex. (A,B) Two-day-old
wild-type (A) and mutant (B) seedlings. (C-H) Three-day-old wild-type (C,E,G)
and mutant (D,F,H) seedlings. E and F are magnified views of C and D,
respectively. Note that ectopic meristematic regions are visible in the
bop1-1 mutant (F,H, arrowheads). The black lines in C and D indicate
the planes of the sections shown in G and H, respectively. (I,J) Six-day-old
wild-type (I) and mutant (J) seedlings. Ectopic outgrowths are distinct on the
adaxial side of the cotyledonary petiole (J, arrowheads). c, cotyledons; p,
leaf primordia. Bars, 20 µm.
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Fig. 6. Development of bop1-1 flowers. (A) Mature wild-type flower. (B,D)
Mature bop1-1 mutant flowers. (C) Magnified view of B. Note the
filamentous organs on the mutant flowers (B,D, arrowheads). (E) Wild-type
petal. (F) bop1-1 mutant petal. The inset shows a magnified view of
the ectopic outgrowths (arrows). Bars, 200 µm in (A,B,D-F), and 50 µm in
(C).
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Fig. 8. Analysis of class I knox gene expression in the bop1-1
mutant. (A) Analysis by RT-PCR of transcripts of the KNAT1, KNAT2 and
KNAT6 genes. Cot, cotyledon (including ectopic outgrowths in the case
of the bop1-1 mutant); Rosette, rosette leaves (including ectopic
outgrowths in the case of the bop1-1 mutant); SAM, shoot apical
meristem region. L, Ler; b, bop1-1. The ß-tubulin
(TUB4) gene was amplified as a positive control. (B) A 23-day-old wild-type
seedling. (C) A detached cotyledon from wild-type plant. (D) A detached leaf
from wild-type plant. Arrows in C and D represent the weak GUS-expressing
region at the petiole base. (E) A 23-day-old bop1-1 mutant seedling.
Note the strong expression of GUS on the hypocotyls and the abaxial side of
leaf petioles. (F) A detached cotyledon from bop1-1 plant. (G) A
detached leaf from bop1-1 plant. Note the strong expression of GUS on
the basal region of petioles (F,G, arrows). (C,D,F,G) Adaxial side views. r,
rosette leaves; c, cotyledons; h, hypocotyls.
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Fig. 9. Phenotypes of double mutants. (A-H) Whole plant and detached rosette leaves
of (A,B) as1-1; (C,D) bop1-1 as1-1 double mutant; (E,F)
as2-2; (G,H) bop1-1 as2-2 double mutant. (I) A rescued
stm-1 seedling plant. (J) A rescued bop1-1 stm-1 seedling
plant. (K) A bp-1 seedling plant. (L) A bop1-1 bp-1 seedling
plant. c, cotyledon. The photographs were taken 25 days (A-H), 30 days (I,J)
and 38 days (K,L) after planting. Bars, 10 mm.
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© The Company of Biologists Ltd 2003
