First published online October 12, 2006
doi: 10.1242/10.1242/dev.02604
Development 133, 4305-4314 (2006)
Published by The Company of Biologists 2006
LONGIFOLIA1 and LONGIFOLIA2, two homologous genes, regulate longitudinal cell elongation in Arabidopsis
Young Koung Lee1,*,
Gyung-Tae Kim2,3,*,
In-Jung Kim4,
Jeongmoo Park1,
Sang-Soo Kwak5,
Giltsu Choi1,
and
Won-Il Chung1,
1 Department of Biological Sciences, KAIST, Daejeon 305-701, Korea.
2 Division of Molecular Biotechnology, Dong-A University, Busan 604-714,
Korea.
3 Environmental Biotechnology Research Center, Gyeongsang National University,
Jinju 660-701, Korea.
4 Faculty of Biotechnology, College of Applied Life Sciences, Cheju National
University, Jeju 690-756, Korea.
5 Laboratory of Environmental Biotechnology, Korea Research Institute of
Bioscience and Biotechnology (KRIBB), 52 Eoen-dong, Yuseong-gu, Daejeon,
305-806, Korea.
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Fig. 1. The lng1-1D mutant shows long petioles, long leaves with
serrated margins, long flowers and long siliques when compared with wild-type
Arabidopsis. (A) 27-day-old wild-type and lng1-1D
plants. (B) Rosette leaves of 39-day-old wild-type and lng1-1D
plants. The right panels show magnified leaf margins and hydathodes of
wild-type (top) and lng1-1D (bottom) plants. (C-E) Flowers
(C), siliques (D), seeds (E) and cotyledons (F) of
wild-type and lng1-1D plants. Scale bars: (A) 5 mm; (B) 10 mm; (C,E)
1 mm; (D,F) 2 mm.
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Fig. 2. Leaf growth of wild-type and lng1-1D mutant plants.
(A,B) Measurement (top) and natural log (bottom) of the average width
(A) and length (B) of 15 leaves of lng1-1D (squares) and wild type
(diamonds).
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Fig. 3. Scanning electron microscope (SEM) analysis of epidermal cells.
Wild-type Col-0 (A-C,G-J) and lng1-1D
(D-F,K-N) plants at 27 (A-F) or 39 (G-N) days. The boxed regions
in A and D are magnified in B and E. Bars in B and E indicate the length of a
single cell. Scale bars: (A,D) 100 µm; (B,E) 20 µm. (C,F) Adaxial region
of the fifth leaf. Scale bar: 10 µm. (G,K) The distal adaxial petal
epidermis of wild-type (G) and lng1-1D (K) plants. Scale bar: 100
µm. (H,L) The proximal adaxial petal epidermis of wild-type (H) and
lng1-1D (L) plants. The bar indicates the length of a single cell;
scale bar: 20 µm. (I,J,M,N) The siliques of wild-type and lng1-1D
plants. (J,N) Higher magnifications of I,M. Scale bars: (I,M) 200 µm; (J,N)
100 µm.
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Fig. 4. The lng1-1D phenotype is caused by overexpression of
LNG1 (At5g15580). (A) Schematic representation of the
T-DNA insertion site in the lng1-1D mutant. BAR, Basta resistance
(Bastar). 4x35S denotes four copies of the 35S enhancer.
(B) Northern blot analysis of neighboring genes. The bottom panel shows
total RNA. (C) LNG1 and its homologs in Arabidopsis
and rice. The unrooted phylogenetic tree was generated by a maximum parsimony
method using the PHYLIP program. Numbers in the tree indicate bootstrap
values. LNG1, At5g15580; LNG2, At3g02170; XP_476397, XP_479072 and AAR01707
include the Oryza sativa. (D-G) Recapitulation analysis with
wild type (D), lng1-1D (E), 35S:LNG1 (F) and
35S:LNG2 (G). The plants were photographed 27 days after seeds were
sown in the greenhouse.
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Fig. 5. Subcellular localization of LNG1-GFP fusion proteins. (A-C)
Bombarded onion cells. (D-G) Transgenic Arabidopsis root.
(A,D) GFP fluorescence. (B,E) Corresponding DAPI fluorescence. (C,F) Merged
pictures. (G) Light microscopic picture of the corresponding cells.
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Fig. 6. Expression analysis of ProLNG1:GUS and
ProLNG2:GUS. (A-D) X-Gluc staining of a
23-day-old ProLNG1:GUS transgenic plant (A-C), and of a
flower cluster from a 6-week-old representative of the same transgenic line
(D). (E-H) X-Gluc staining of a 23-day-old
ProLNG2:GUS transgenic plant (E-G), and a flower cluster
from a 6-week-old representative of the same transgenic line (H).
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Fig. 7. LNG1 and LNG2 additively promote longitudinal organ
elongation. (A) T-DNA insertion sites of the lng1-2, lng1-3,
lng2-1, and lng2-2 mutants. (B) Expression analysis of
LNG1 and LNG2 in the wild type, lng1-3, lng2-1, lng1-3
lng2-1, and lng1-1D mutants. (C) Phenotypes of the wild
type, lng1-3, lng2-1, lng1-3 lng2-1, and lng1-1D plants. Top
panel, 8-day-old cotyledons. Scale bar: 5 mm. Second panel, 27-day-old plants.
Scale bar: 10 mm. Third panel, siliques. Scale bar: 5 mm. Bottom panel,
flowers. Scale bar: 5 mm.
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Fig. 8. LNG1 and LNG2 regulate longitudinal cell expansion
independently of ROT3. (A) RT-PCR expression analysis of
ROT3, CYP90D1, AN and ATHB13 in wild-type, lng1-1D and
lng1-3 lng2-1 plants. (B) Expression analysis of LNG1
and LNG2 in wild-type and rot3-1 plants. (C) Length
of the leaf blade. (D) Length of the leaf petiole. (E) Width of
the leaf blade. Analyses were performed on the fifth leaves of 39-day-old
plants. Measurement of cell numbers (F) and cell sizes (G) of
the fifth leaves during different developmental stages. Paradermal images of
palisade cells were used for measurements.
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© The Company of Biologists Ltd 2006
