A Large Scale Analysis of cDNA in Arabidopsis thaliana: Generation of 12,028 Non-redundant Expressed Sequence Tags from Normalized and Size-selected cDNA Libraries

Abstract

For comprehensive analysis of genes expressed in the model dicotyledonous plant, Arabidopsis thaliana, expressed sequence tags (ESTs) were accumulated. Normalized and size-selected cDNA libraries were constructed from aboveground
organs, flower buds, roots, green siliques and liquid-cultured seedlings, respectively, and a total of 14,026 5′-end ESTs
and 39,207 3′-end ESTs were obtained. The 3′-end ESTs could be clustered into 12,028 non-redundant groups. Similarity search
of the non-redundant ESTs against the public non-redundant protein database indicated that 4816 groups show similarity to
genes of known function, 1864 to hypotheticalgenes, and the remaining 5348 are novel sequences. Gene coverage by the non-redundant
ESTs was analyzed using the annotated genomic sequences of approximately 10 Mb on chromosomes 3 and 5. A total of 923 regions
were hit by at least one EST, among which only 499 regions were hit by the ESTs deposited in the public database. The result
indicates that the EST source generated in this project complements the EST data in the public database and facilitates new
gene discovery. The EST sequence data of individual cDNA clones are available at the web site: http://www.kazusa.or.jp/en/plant/arabi/EST/.

Full text

DNA RESEARCH
7,
175-180 (2000)
A Large Scale Analysis of cDNA in Arabidopsis thaliana:
Generation of 12,028 Non-redundant Expressed Sequence Tags
from Normalized and Size-selected cDNA Libraries
Erika ASAMIZU, Yasukazu NAKAMURA, Shusei SATO, and Satoshi TABATA*
Kazusa DNA
Research
Institute, 1532-3 Yana, Kisarazu,
Chiba
292-0812,
Japan
(Received 19 May 2000)
Abstract
For comprehensive analysis of genes expressed in the model dicotyledonous plant, Arabidopsis thaliana,
expressed sequence tags (ESTs) were accumulated. Normalized and size-selected cDNA libraries were con-
structed from aboveground organs, flower buds, roots, green siliques and liquid-cultured seedlings, respec-
tively, and
a
total of 14,026
5'-end
ESTs and 39,207 3'-end ESTs were obtained. The 3'-end ESTs could be
clustered into 12,028 non-redundant groups. Similarity search of the non-redundant ESTs against the public
non-redundant protein database indicated that 4816 groups show similarity to genes of known function, 1864
to hypothetical genes, and the remaining 5348 are novel sequences. Gene coverage by the non-redundant
ESTs was analyzed using the annotated genomic sequences of approximately 10 Mb on chromosomes 3 and
5.
A total of
923
regions were hit by
at
least one EST, among which only 499 regions were hit by the ESTs
deposited in the public database. The result indicates that the EST source generated in this project com-
plements the EST data in the public database and facilitates new gene discovery. The EST sequence data
of individual cDNA clones are available
at
the web site: http://www.kazusa.or.jp/en/plant/arabi/EST/.
Key words:
Arabidopsis
thaliana;
cDNA; EST
1.
Introduction
Arabidopsis thaliana
has been adopted as
a
model or-
ganism in the study of plant biology since
it
has the ad-
vantages
of
small size, short generation time, and ease
of transformation.1 Because the
A.
thaliana genome
is
the smallest genome among known higher plant species
(130-140 Mb),2'3 the genome sequencing project of this
plant
is
underway
as a
joint project
of
Japan, Europe,
and the United States.4 To date, two of five chromosomes
(chromosomes
2
and 4) have been sequenced except
for
the nucleolar organizer regions and centromeres,2'3 and
sequencing
of
the remaining three chromosomes
is
near
completion.
Under these circumstances,
the
accurate assignment
of protein coding regions on the genomic sequence gains
importance
as the
logical next step.
In
this respect,
information
on
cDNA structure
is
essential. Also,
comprehensive analysis
of
cDNA sequences
is an
effec-
tive way
to
catalogue genes expressed
in an
organism
with
a
large genome.
A
large number
of
EST
(ex-
pressed sequence tag) sequences
of
several crop plants
Communicated by Mituru Takanami
* To whom correspondence should
be
addressed. Tel. +81-438-
52-3933,
Fax. +81-438-52-3934, E-mail: tabata@kazusa.or.jp
have been deposited
in the
public database, dbEST
(http://www.ncbi.nlm.nih.gov/dbEST/dbESTj3ummary.
html).
In
addition, EST accumulation of several model
plants have been initiated.5"7
In
A.
thaliana, more than 45,000 EST sequences have
been deposited in dbEST, including sequences from large-
scale EST projects promoted
by
two consortia
of
lab-
oratories, one
in
France
and the
other
in the
United
States.8"10 The French program generated sequence data
from ten kinds
of
cDNA libraries prepared from differ-
ent tissues, organs and developmental stages. They de-
posited
the 5'- and
3'-end sequences
of
approximately
6,000 non-redundant clones in dbEST.8'9 The U.S. group
produced 31,000 ESTs mainly from a single library made
from
a
mixture of mRNAs from four different tissues.10
These EST clones altogether cover approximately 34% of
the predicted genes on chromosome 4.3
To complement
the
EST data currently available
in
the public database and facilitate new gene discovery, we
constructed normalized and size-selected cDNA libraries
from five different tissues of A.
thaliana,
and accumulated
5'-end
and 3'-end ESTs.
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176A Large Scale EST Project in A. thaliana
[Vol.
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s
z
2500
2000
1500
1000
500• _n n
0.5-
1.0-1.5-
<2.0
2.0-
<2.5
2.5-
3.0-
<3.0 <3.5
Insert size (kb)
3.5-
<4.0
4.0-
<4.5
4.5-
<5.0
>5.0
Figure 1. Size distribution of the inserts in analyzed cDNA clones from the normalized (solid bars) and size-selected libraries (gray
bars) of aboveground organs.
2.
Materials and Methods
2.1.
Preparation of tissues
Arabidopsis thaliana Columbia accession was used for
analysis and was grown in soil under a 16 hr photope-
riod at 22°C. Aboveground organs were harvested from
2-
to 6-week-old plants. Flower buds and green siliques
were also collected from the soil-grown plants. For liq-
uid culture, sterile seeds were sown in medium [1/2 B5
medium,11
1/1000
HYPONeX (Hyponex Japan), 1% su-
crose, pH adjusted to 5.7] and grown under continuous
light at 22° C with rotation for 2 weeks. Seedlings and
roots were collected from the liquid-cultured plants.
RNA and construction of
2.2.
Isolation of poly(A)+
cDNA libraries
Total RNA was extracted from aboveground or-
gans,
flower buds, roots, and liquid-cultured seedlings
by the guanidium thiocyanate/CsCl ultracentrifugation
method, and from green siliques by the SDS/phenol
method as described previously.5'7 Purification of
poly(A)+ RNA, conversion to cDNA, and size-selection
of cDNA was performed as described.5 Normalization
was performed for the library containing 0.5- to 3-kb frag-
ments as described.5'12 The names of cDNA libraries re-
fer to the tissue used for construction: AP, aboveground
organs; FB, flower buds; RZ, roots; SQ, green siliques;
pAZNII, liquid-cultured seedlings.
2.3.
Template preparation and
sequencing
For generation of all the
5'-end
sequences as well as
some of the 3'-end sequences from the AP and RZ li-
braries, PCR amplified fragments were used as a tem-
plate. Vector-derived sequences were used as primers (5'-
TGTGCTGCAAGGCGATTAAGTTGGG-3', and 5'-
TCATTAGGCACCCCAGGCTTTACAC-3'), and PCR
was performed by Taq DNA polymerase (TaKaRa,
Japan) using a Perkin-Elmer 9600 Thermal Cycler:
30 cycles of 10 sec at 98CC, 6 min at 68°C, and a final
extension for 10 min at 72°C. The amplified products
were precipitated by adding 1/3 to the final volume of
20%
PEG6000 in 2.5 M NaCl. Plasmid DNA was used
as a template for generation of the rest of 5'- and 3'-end
sequences. Plasmid DNA preparation and insert size de-
termination of each clone was performed as described.5
Sequence reaction was performed by Dye Terminator,
dRhodamine Terminator, and BigDye Terminator Cy-
cle Sequencing Ready Reaction Kit (PE Applied Biosys-
tems,
USA) and electrophoresed on the automated DNA
sequencers (ABI PRISM 373 and 377XL, PE Applied
Biosystems, USA).
2.4-
Sequence
data analysis
Only the 3'-end sequences were subjected to the data
analysis process. The vector-derived sequence and am-
biguous sequences were removed from the collected EST
sequences prior to the computer-aided analyses. Each
sequence was translated into its amino acid sequences in
six frames and subjected to similarity search against the
non-redundant protein database provided by NCBI using
the BLAST algorithm.13 Similarity between a deduced
amino acid sequence and a known sequence was judged
to be significant when the P-value was less than
1.0~14.
To identify the number of independent EST species, clus-
tering of the EST sequences was performed. The 3'-end
sequences were compared with a dataset of itself using
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No.
3]
E. Asamizu
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Table
1.
Number
of
5'-cnd
and
3'-end ESTs generated from
cDNA libraries
of
five different tissues.Table
2.
Classification
of
3'-end ESTs
by
similarity search against
the non-redundant protein database.
Tissue
Aboveground organs
Flower buds
Roots
Green siliqiies
Liquid-cultured seedlings
Total
Library type
Normalized
Size-selected
Normalized
Normalized
Size-selected
Normalized
Size-selected
Normalized
Number
of
5'
end
ESTs
4996
2172
ND
5798
245
ND
ND
815
14026
Number
of
3'
end
ESTs
6863
1753
5827
8505
3161
11843
909
346
39207
ND:
Not
determined
the BLASTN program
and
clones that showed over 95%
identity
for
more than
50 bp
were included
in the
same
group.
3.
Results
and
Discussion
3.1.
Quality
of
cDNA libraries
The size distribution
of the
inserts
in
cDNA
was an-
alyzed
for the
clones from
the
cDNA libraries
of
above-
ground organs.
As
shown
in Fig. 1,
72.3%
of the
clones
from
the
normalized library contained inserts
of 0.5 to
1.5
kb, while 96.0%
of
the clones from
the
size-selected
li-
brary
had
inserts longer than
2.5 kb. The
average insert-
length
of
the clones
in the
normalized library was
1.28 kb,
whereas that
of the
size-selected library
was 3.17 kb. It
is therefore evident that
the
size selection procedure
is
effective
for
generation
of
long cDNA species.
The quality
of the
libraries with respect
to the in-
tactness
of
cDNA
was
assessed
by
comparison
of the
5'-end
sequences
to
known protein sequences. Among
116 clones randomly chosen from
the
normalized library
and
122
clones from
the
size-selected library,
74
(63.8%)
and
85
(69.7%) were found
to
contain
a
translation
ini-
tiation codon, respectively, indicating that roughly
two-
thirds of
the
cDNA clones
are
full-length
in
both libraries.
This result shows that
the two
libraries contain
an
abun-
dance
of
intact cDNA species with shorter
and
longer
sizes.
However,
we
only assessed
the
quality
of
libraries
using those prepared from aboveground organs.
The
quality
may be
different among libraries from different
tissues.
3.2. Generation
of
ESTs
cDNA clones were randomly chosen from
the
cDNA
libraries constructed,
and a
total
of
14,026 clones were
Similarity
Genes
of
known function01
Hypothetical genes'"
No similarity"
Total
Number
of
clones
24892
5071
9244
39207
Number of non-
redundant ESTs
4816
1864
5348
12028
a) showed similarity to genes of known function, b) showed
similarity to hypothetical genes that have no definition of
function, c) showed no similarity
sequenced from
the
5'-ends
and
39,207 clones were
sc-
quenced from
the
3'-ends.
The
number
of
ESTs
gen-
erated from
the
respective libraries
are
summarized
in
Table
1. The GC
content
of the
randomly selected
659 ESTs (279,604 bases)
was
estimated
to be
43.4%.
To identify
the
number
of
independent
EST
species,
clustering
of the
3'-EST sequences
was
performed.
As a
result,
the
39,207 3'-EST sequences were clustered into
12,028 independent groups. This number
is
supposed
to
be close
to the
actual number
of
gene species represented
by ESTs. However,
a
more accurate number
of
indepen-
dent gene species should
be
obtained
by
allocating
the
EST sequences
on the
genome, because
the
stringency
used
for
clustering was
not
strict (95% identity
for
50
bp).
3.3.
Sequence
similarity
of
ESTs
When
the
non-redundant
EST
groups deduced from
the 3'-end ESTs were searched
for
similarity using
the non-redundant protein database, 6680 groups
had
significant similarity
to the
registered sequences
and
the remaining 5348 groups were novel. Among
the
6680
EST
groups with significant similarity, 4816 showed
similarity
to
genes with known function
and the re-
maining
1864 to
hypothetical genes, with
no
func-
tional definition largely predicted from
the A.
thaliana
genome sequences (Table
2).
Genes whose functions
could
be
predicted from
a
similarity search were clas-
sified according
to the
biological roles
or
biochemical
functions2
as
shown
in
Table
3. The
search results
of
the
individual clone
are
available
at the web
site,
http://www.kazusa.or.jp/en/plant/arabi/EST/.
3.4- Estimation
of
gene coverage
by
ESTs
Gene coverage
of the
non-redundant
EST
groups
was
investigated using
the
annotated genomic sequences,
10,009,832
bp in
length,
on
chromosomes
314 and 515
(http://www.kazusa.or.jp/kaos/).
The
sequences taken
were
of 1 PI
clone
on
chromosome
3, and 106 PI and
30
TAC
clones
on
chromosome
5.
Along
the
genomic
sequences, 2324 regions have been assigned
as
potential
protein-coding genes. Analysis indicated that
788
were
hit
by at
least
one EST
group.
In
addition,
135 EST
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178A Large Scale EST Project
in A.
thaliana [Vol.
7,
| Aboveground organs
15.3%
^M Flower buds
8.1%
I
I
Roots 21.29!
•B
Green siliques
22.8%
I Liquid-cultured secdhncs
0.7'v
•I 2
tissues
19.4%
I I 3 lissues 8.4%
I I 4 lissues 3.8%
I I 5 tissues 0.3%
Figure 2. The proportions of EST groups identified only in one of the five tissues and those identified in two to five tissues. The
proportion of each category are given as percentages and indicated by color codes.
Table 3. Classification of the non-redundant EST groups with
similarity to known protein genes by their functional categories.
Functional categories
Energy metabolism
Regulatory functions
Cellular structure, organization and biogenesis
Protein fate
Signal transduction
Protein synthesis
Transport and binding proteins
Cellular processes
Secondary metabolism
Growth and development
Fatty acid and phospholipid metabolism
Amino-acid biosynthesis
Environmental response
Pathogen responses
DNA metabolism
General transcription
Purines, pyrimidines, nucleosides, and nucleotides
Central intermediary metabolism
Biosynthesis of cofactors, prosthetic groups, and carriers
Other categories
Unclassified
Total
Number of non-
redundant groups
538
483
416
369
360
328
319
218
209
184
132
125
113
99
89
76
68
53
52
23
562
4816
groups could
be
located
at
regions where no gene assign-
ment
has
been done. Gene coverage
by
ESTs deposited
in the database was examined, and only 499 out of
923
re-
gions
hit by our
EST groups were found
to hit.
We also analyzed gene coverage by mapping of the EST
groups on the completed sequence
of
A.
thaliana
chromo-
some
2, on
which 4037 genes have been assigned.2
As a
result, 1775
EST
groups were allocated
on the
genomic
sequence, of which 626 groups were found
to
have similar
sequences in the registered ESTs. Although the gene cov-
erage data observed
for
different chromosomal sequences
can not
be
compared directly, the data obviously indicate
that
the
non-redundant ESTs generated
in
this project
contain many new cDNA species.
3.5. Classification
of
ESTs with respect
to
tissue-
specific
expression
To gain information
on the
expression specificity
of
genes identified
by
EST analysis,
the
occurrence
of
non-
redundant ESTs
in the
population
of
3'-end ESTs
gen-
erated from each tissue
was
counted.
The
12,028
non-
redundant
EST
groups were classified into nine cate-
gories:
The
groups identified only
in one of
the five
tis-
sues,
and
those identified
in
two
to
five tissues. The
per-
centages
of the EST
groups classified
in
each category
to
the
total non-redundant EST groups are shown
in the
pie chart
in Fig. 2.
Although
the
population
of the 3'-
end ESTs
in
each tissue
is not
large enough
to
speculate,
the proportion
of
EST groups identified only
in one of
the five tissues
was
surprisingly high (68.1%) compared
with those identified
in
multiple tissues.
The
result
im-
plies that
the
classified EST groups
are
good sources
for
finding genes with tissue-specific expression.
In
Table
4,
the identity
of
genes which
are
abundantly represented
by ESTs
in
four different tissues (aboveground organs,
flower buds, roots
and
green siliques)
is
listed. Some
genes
on
this list have been reported
to
show tissue-
specific expression.16"18 However, five kinds of ribosomal
protein genes
are
seen
in the
flower
bud
groups, indicat-
ing the necessity
of
further analysis with more large EST
populations.
The EST sequences reported
in
this paper appear
in the
GenBank/EMBL/DDBJ databanks with accession num-
bers AB038710-AB038726, AV439465-AV442830
and
AV517879-AV567728.
Acknowledments:
We
thank
A.
Watanabe,
T.
Wada,
N.
Nakazaki,
K.
Naruo,
M.
Ishikawa,
and M.
Yamada
for
excellent technical assistance. This work was
supported
by the
Kazusa DNA Research Institute Foun-
dation.
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No.
3] E.
Asamizu
et al. 179
Table
4. The
identity
of
genes abundantly represented
by
3'-end ESTs
in
aboveground organs, flower buds, roots
and
green siliques.
Number of
clones Definition
of
the
most similar sequence
Aboveground organs
8 COL2 [Arabidopsis thaliana]
8 strong similarity to Arabidopsis 2A6 (gb!X83096). [Arabidopsis thaliana]
6 ethylene-forming enzyme [Arabidopsis thaliana]
5 unknown
5 involved in starch metabalism [Solanum tuberosum]
5 unknown
5 nitrate reductase NR1 (393 AA) [Arabidopsis thaliana]
5 unknown
5 unknown
4 beta-l,3-glucanase 2 [Arabidopsis thaliana]
Flower buds
19 PsCLl
8
ribosomal preprotein (AA -49 to 96) [Pisum sativum]
12 unknown
11 similar to Prunus pcctinesterase (gb!X95991). [Arabidopsis thaliana]
11 ribosomal protein L30 [Lupinus luteus]
10 acidic ribosomal protein P3a [Zea mays]
8 anther-specific gene product; putative [Brassica campestris]17
8 putative ribosomal protein [Arabidopsis thaliana]
8 similar to lipid transfer protein [Brassica
rapa]17
7 putative ribosomal protein SI6 [Arabidopsis thaliana]
7 NAP16kDa protein [Arabidopsis thaliana]
Root
28 jasmonate inducible protein isolog [Arabidopsis thaliana]
18 peroxidase ATP1 la [Arabidopsis thaliana]
16 cucumisin [Arabidopsis thaliana]
15 cytochrome P450 monooxygenase [Arabidopsis thaliana]
14 peroxidase ATP8a [Arabidopsis thaliana]
13 putative plasma membrane-cell wall linker proteins [Arabidopsis thaliana]"5
12 flavonol synthase [Arabidopsis thaliana]
11 beta-glucosidase [Arabidopsis thaliana]
9 Dr4 [Arabidopsis thaliana]
8 ABC transporter (PDR5-like) isolog [Arabidopsis thalianai
Green siliques
29 APG protein isolog [Arabidopsis thaliana]
26 12S cruciferin seed storage protein [Arabidopsis thaliana]18
26 gamma-VPE [Arabidopsis thaliana]
24 thioesterase homolog [Arabidopsis thaliana]
24 dihydroflavonol 4-reductase [Arabidopsis thaliana]
17 putative pectinesterase [Arabidopsis thaliana]
14 germin-like protein [Arabidopsis thaliana]
13 12S storage protein CRB [Arabidopsis thaliana]18
11 unknown
10 putative protein [Arabidopsis thaliana]
References
6.
Asamizu,
E.,
Nakamura,
Y.,
Sato,
S., and
Tabata,
S.
2000,
Generation
of 7,137
Non-redundant Expressed
Se-
1.
Meinke,
D. W.,
Cherry,
J. M.,
Dean,
C. D.,
Rounsley,
S.,
quence Tags from
a
Legume, Lotus japonicus,
DNA Res.,
and Koornneef,
M. 1998,
Arabidopsis thaliana:
a
model
7,
127-130.
plant
for
genome analysis, Science,
282,
662-682.
7.
Nikaido,
I.,
Asamizu,
E.,
Nakajima,
M.,
Nakamura,
Y.,
2.
Lin, X.,
Kaul,
S.,
Rounsley,
S. et al. 1999,
Sequence Saga,
N., and
Tabata,
S.
2000, Construction
of a
gene
and analysis
of
chromosome
2 of the
plant Arabidopsis catalogue
of a
marine
red
alga, Porphyra yezoensis.
I.
thaliana, Nature,
402,
761-768. Generation
of
10,154 expressed sequence tags,
DNA Res.,
3.
Mayer,
K.,
Schiiller,
C,
Wambutt,
R. et al. 1999, Se-
this issue.
quence
and
analysis
of
chromosome
4 of the
plant
Ara- 8.
Hofte,
H.,
Desprez,
T.,
Amselem,
J. et
al. 1993,
An
inven-
bidopsis thaliana, Nature,
402,
769-777. tory
of
1152 expressed sequence tags obtained
by
partial
4.
Bevan,
M. 1997,
Objective:
the
complete sequence
of a
sequencing
of
cDNAs from
Arabidopsis
thaliana, Plant
J.,
plant genome, Plant Cell,
9,
476-478.
4,
1051-1061.
5.
Asamizu,
E.,
Nakamura,
Y.,
Sato,
S.,
Fukuzawa,
H., and 9.
Cooke,
R.,
Raynal,
M.,
Laudie,
M. et al. 1996,
Further
Tabata,
S.
1999,
A
large scale structural analysis
of
cD- progress towards
a
catalogue
of all
Arabidopsis genes:
NAs
in a
unicellular green alga, Chlamydomonas rein- analysis
of a set of
5000 non-redundant ESTs, Plant
J.,
hardtii.
I.
Generation
of
3433 non-redundant expressed
9,
101-124.
sequence tags,
DNA Res., 6,
369-373.
10.
Newman,
T., de
Bruijn,
F. J.,
Green, P.
et
al. 1994, Genes
galore:
a
summary
of
methods
for
accessing results from
by guest on June 1, 2013http://dnaresearch.oxfordjournals.org/Downloaded from

180A Large Scale EST Project in A. thaliana [Vol. 7,
large-scale partial sequencing of anonymous Arabidopsis
cDNA clones, Plant Physioi, 106, 1241-1255.
11.
Horsch, R. B., Fry, J., Hoffman, N., Neidermeyer, J.,
Rogers, S. G., and Fraley, R. T. 1988, Plant Molecular
Biology Manual, Kluwer Academic Publishers, A5: 1-9.
12.
Bonaldo, M. F., Lennon, G., and Soares, M. B. 1996, Nor-
malization and subtraction: two approaches to facilitate
gene discovery, Genome Res., 6, 791-806.
13.
Altschul, S. F., Gish, W., Miller, W., Myers, E. W., and
Lipman, D. J. 1990, Basic local alignment search tool, J.
Mol. Bioi, 215, 403-410.
14.
Sato, S., Nakamura, Y., Kaneko, T., Katoh, T., Asamizu,
E., and Tabata, S. 2000, Structural Analysis of
Arabidop-
sis thaliana Chromosome 3. I. Sequence Features of the
Regions of 4,504,864 bp Covered by Sixty PI and TAC
Clones, DNA Res., 7, 131-135.
15.
Sato, S., Nakamura, Y., Kaneko, T. et al. 2000,
Structural Analysis of
Arabidopsis
thaliana Chromosome
5.
X. Sequence Features of the Regions of 3,076,755 bp
Covered by Sixty PI and TAC Clones, DNA Res., 7, 31-
63.
16.
Neuteboom, L. W., Ng, J. M., Kuyper, M., Clijdesdale,
O. R., Hooykaas, P. J., and van der Zaal, B. J. 1999, Iso-
lation and characterization of cDNA clones correspond-
ing with mRNAs that accumulate during auxin-induced
lateral root formation, Plant Mol. Bioi, 39, 273-287.
17.
Kim, H. U. and Chung, T. Y. 1997, Characterization
of three anther-specific genes isolated from Chinese cab-
bage,
Plant Mol. Bioi., 33, 193-198.
18.
Parcy, F., Valon, C, Kohara, A., Misera, S.,
and Giraudat, J. 1997, The ABSCISIC ACID-
INSENSITIVE3, FUSCA3, and LEAFY COTYLE-
D0N1 loci act in concert to control multiple aspects of
Arabidopsis seed development, Plant Cell, 9, 1265-1277.
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