Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany
* Author for correspondence (e-mail: szachgo{at}mpiz-koeln.mpg.de)
Accepted 25 January 2005
![]() |
SUMMARY |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Key words: ROXY1, Glutaredoxin, Flower development, Perianth, Arabidopsis
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Whereas the ABC genes control the identity of the organs, initiation of
organ primordia is determined before the onset of the class A, B and C
activity. For example, in mutants from the class B gene PISTILLATA
(PI), feminization of the third whorl organs becomes visible only
after initiation of the respective primordia
(Hill and Lord, 1989).
Primordia formation requires the proper allocation of progenitor cells and
regulated control of cell divisions, processes that are presumably under
genetic control. Petal primordia are initiated when cells in the L2 layer of
the floral primordium divide periclinally, rather than anticlinally
(Hill and Lord, 1989
). Several
mutants have recently been characterized in Arabidopsis that disturb
primordia initiation and thus develop an either increased or decreased floral
organ number. In clavata mutants, floral organ number is increased
because of an enlargement of the floral meristem
(Clark et al., 1993
). In
perianthia mutants, five organs are formed in the first three whorls
(Running and Meyerowitz,
1996
), indicating that PAN normally establishes a
tetramerous whorl architecture. UFO encodes a F-box protein required
for the activation of the class B gene expression, and strong ufo
mutants resemble class B mutant flowers
(Levin and Meyerowitz, 1995
;
Wilkinson and Haughn, 1995
).
Additionally, UFO is also involved in the early control of petal
outgrowth, probably by counteracting inhibitory effects non-autonomously
exerted by AG (Durfee et al.,
2003
; Laufs et al.,
2003
). Two other genes have been shown to affect predominantly
initiation of petal development: PETAL LOSS (PTL), a
trihelix transcription factor (Brewer et
al., 2004
); and RABBIT EARS (RBE), a
SUPERMAN-like zinc finger protein (Takeda
et al., 2004
). In ptl mutants, the number of petals is
reduced and if they develop, the orientation is altered and the size reduced.
PTL is not expressed in petal primordia, but between sepal primordia,
indicating a rather indirect effect on petal development
(Brewer et al., 2004
).
Similarly, petal initiation in rbe mutants is disturbed and in a
strong mutant only a reduced number of filamentous organs is formed in the
second whorl. RBE is expressed in petal precursor cells and petal
primordia and controls second whorl organ development independently of organ
identity (Takeda et al.,
2004
). As ptl and rbe mutants still form
aberrant petals, primordia initiation seems to be a complex process that is
regulated by additional factors.
Here, we report on roxy1 mutants that displays defects in petal
initiation and also abnormalities during later petal development.
ROXY1 encodes a glutaredoxin (GRX), of which many isoforms exist in
different organisms, such as E. coli, yeast, animals, humans and
plants. GRXs are oxidoreductases that are involved in many different cellular
processes, mainly in the response to oxidative stress
(Fernandes and Holmgren,
2004). Our data show a novel function during the regulation of
flower development for a GRX that belongs to a subgroup specific for higher
plants.
![]() |
Materials and methods |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Microscopy
Inflorescences or flowers from GFP transgenic plants were observed under
the binocular microscope LEICA MZ-FLIII. Images were made using a digital
camera (KY-F70). For scanning electron microscopy (SEM), we followed the
protocol described by Zachgo et al.
(Zachgo et al., 1995).
Molecular cloning of ROXY1 gene
To identify the flanking sequence adjacent to the T-DNA in
roxy1-1, genomic DNA was prepared from the mutant and digested with
DraI. An adaptor (a mix of two oligonucleotides:
5'-GTAATACGACTCACTATAGGGCACGCGTGGTCGACGGCCCGGGCTGGT-3' and
5'-ACCAGCCC-3') was ligated to the ends of digested genomic DNA
using ligase from Promega (Mannheim, Germany). First, PCR was carried out with
adaptor primer 1 (5'-GTAATACGACTCACTATAGGG-3') and T-DNA left
border primer (5'-ACGACGGATCGTAATTTGTCG-3'); then, a second PCR
was performed with the nested adaptor primer 2
(5'-ACTATAGGGCACGCGTGGT-3') and a nested left border primer
(5'-ATATTGACCATCATACTCATTGC-3'). Expand High fidelity polymerase
(Roche, Mannheim, Germany) was used in the reaction. PCR products were gel
purified and sequenced. The cDNA cloning was performed using the
5'/3' cDNA RACE kit (Roche, Mannheim, Germany) as indicated in the
manufacturer's instructions.
Generation of double mutants
To obtain double mutants, roxy1-3 was crossed either with
homozygous (ptl-1; rbe-2; ap1-10; ap2-5;
lug-1; ap3-3 and ufo-2) or heterozygous
(ag-1) lines. All F1 plants produced wild-type flowers. Novel
phenotypes were identified in segregating F2 populations and genotypes of
double mutants were confirmed by PCR.
RNA isolation and RT-PCR analysis
Total RNA was extracted with the RNeasy kit (Qiagen). Different organs of
6-week-old plants were used, except for the root, which originates from a
three-week liquid culture. First strand cDNA was synthesized from 2 µg of
total RNA using 200 U SuperScriptTM II Reverse Transcriptase (Invitrogen)
according to the supplier's instructions. PCR reactions (58°C annealing
temperature with 40 seconds extension for 31 cycles) were carried out using
ROXY1-specific primers from the 5' UTR (100 bp upstream of the
start codon; 5'-TCGCGAATTCCCAACAAACTTTAGCCAATCCCTC-3') and from
the 3' UTR (220 bp downstream of the stop codon;
5'-ACGCGAATTCTGTTTACTATTATGATTTAATGAGAGC-3'). PCR products were
loaded on an ethidium bromide-stained 1.2% (w/v) agarose gel. Images were made
with the PhosphorImager Typhoon 8600 (Amersham Biosciences). 18S rRNA
(Katz et al., 2004) was used
as an internal control.
Complementation experiment
A 4468 bp ROXY1 genomic fragment was amplified using the Expand
High fidelity PCR system (Roche) with the gene-specific primers
5'-GCGTAGATCTCAATAGTCGAGGATCATTCGGAGTGC-3' and
5'-GTACGCTAGCCTTCAAGCTTCACCTATCTCACTCATAGTC-3', digested using
BglII and NheI and subcloned into pGSA1252
(www.chromdb.org/plasmids/pGSA1252.html).
A recombinant plasmid containing the correct coding sequence was transformed
into the Agrobacterium tumefaciens strain GV3101, and introduced into
roxy1-3 mutants using the floral infiltration method
(Clough and Bent, 1998). T1
transformants were obtained by BASTA selection.
In situ RNA hybridization and histochemistry
RNA in situ hybridization was performed as previously described by
transcription from PCR templates containing a T7 polymerase binding site at
the 3' end (Zachgo,
2002). To avoid cross-hybridization with other GRXs, the
ROXY1 antisense probe was prepared using a unique 245 bp fragment
from the ROXY1 5' end
(5'-GCGGAATTAACCCTCACTAAAGGGCCAACAAACTTTAGCCAATC-3' and
5'-GCTCGTAATACGACTCACTATAGGGCACGTGCTCACGCTGAAGATC-3') and a unique
225 bp fragment from the ROXY1 3' end
(5'-GCGGAATTAACCCTCACTAAAGGGTCTGATCCCTTCCTCTGCTTTC-3' and
5'-GCGCGTAATACGACTCACTATAGGGCTGTTTACTATTATGATTTAATG-3') as
templates. Control experiments on roxy1-3 inflorescences confirmed
probe specificity. The AG antisense probe was generated by PCR with
the primer pair:
5'-GTGGAATTAACCCTCACTAAAGGGAGCTTACGAGCTCTCTGTTCTTTG3' and
5'-GTGCGTAATACGACTCACTATAGGGCAATTCACTGATACAACATTCATGG-3'. T7 RNA
polymerase (Roche) was used for in vitro transcription. GUS staining was done
as described by Müller et al.
(Müller et al.,
2001
).
ROXY1::ROXY1-GFPplasmid construction
The GFP ORF with stop codon was amplified using primer
5'-TAGGCGCGCCCATGGGTAAAGGAGAAGAACTTTTC-3' and
5'-GAACGAGCTCGTCGACCGGTGAGGATCCTTATTTGTATAG-3', and subcloned into
the binary vector pGPTV-HPT. The regions 3912 bp upstream from the
ROXY1 stop codon TGA and 445 bp downstream of the stop codon were
further amplified using primer pairs:
5'-TGCGTCTAGAACTACATAAAAGCCTTTCAG-3' and
5'-TAGGCGCGCCGAGCCAGAGAGCGCCGGCGTCTTTGAGAA-3'; and
5'-GCCGACCGGTTCCCTTCCTCTGCTTTCTTTTTTCTTTTC-3' and
5'GTACGAGCTCCTTCAAGCTTCACCTATCTCACTCATAGTC-3'. The two fragments
were fused up- and downstream to the GFP ORF, respectively. The clone,
selected for transformation into plants, was confirmed by sequencing.
Site-directed mutagenesis
Point mutations in specific amino acids of ROXY1 were introduced by a
PCR-mediated mutagenesis strategy as described by Rouhier et al.
(Rouhier et al., 2002). To
introduce a serine/cysteine exchange mutation, pairs of mutagenic oligomers
(mutagenic bases are written in lowercase) were used:
5'-TGATCTTCAGCGTGAGCACGTcCTGC-3' and
5'-GCAGgACGTGCTCACGCTGAAGATCA-3' (C49S);
5'-TGATCTTCAGCGTGAGCACGTGCTGCATGTcCCA-3' and
5'TGGgACATGCAGCACGTGCTCACGCTGAAGATCA-3' (C52S); and
5'-CCTCATTCGTCTCCTCGGCTcCT-3' and
5'-AGgAGCCGAGGAGACGAATGAGG-3' (C90S). After sequencing, the three
mutated ROXY1 genes were cloned into the pBAR-35S vector
(Müller et al., 2001
) and
transformed into the roxy1-3 mutant. Complementation was analyzed in
transgenic T1 plants, obtained by BASTA selection.
![]() |
Results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
|
|
ROXY1 encodes a protein of the glutaredoxin family
For isolation of the full-length ROXY1 cDNA, 5' and 3'
Rapid Amplification of cDNA ends (RACE) reactions were conducted. The 5'
RACE allowed us to locate the transcription initiation site 100 bp upstream of
the ATG start codon of translation. By 3' RACE, three cDNAs with
3' UTRs of different lengths were isolated. The longest 3' UTR
comprises 220 bp downstream of the TGA stop codon, the other two are 159 and
147 bp long. By RT-PCR analysis, no ROXY1 gene expression could be
detected in the roxy1-2 and roxy1-3 mutants
(Fig. 2C), indicating that they
are null mutants.
The ROXY1 open reading frame consists of one single exon, encoding
136 amino acids (Fig. 2B).
Homology searches revealed that the ROXY1 protein belongs to the family of
glutaredoxins (GRXs), which are represented by a number of isoforms in
different species, including procaryotes as well as lower and higher
eukaryotes (see below). GRXs are small redox proteins that can reduce
disulfides via a dithiol or monothiol mechanism by way of conserved cysteines.
The dithiol mechanism depends on an active site that contains a conserved N-
and C-terminal cysteine (CXXC), and can reduce both, protein disulfides and
glutathione (GSH) mixed disulfides. Monothiol GRXs (CXXS) can only reduce GSH
mixed disulfides (Vlamis-Gardikas and
Holmgren, 2002; Lemaire,
2004
). These oxidoreductases have thus far mainly been studied in
E. coli, yeast and mammal cells, and play a major role in the
response to oxidative stress (Fernandes
and Holmgren, 2004
). For plants, information on the function of
GRXs is scarce. roxy1 represents the first mutant revealing a
function for a plant glutaredoxin during flower development.
Cysteine 49 is crucial for proper function of ROXY1 during petal development
In Arabidopsis, GRXs of the CPYC type exist (e.g. At5g20500),
sharing the active site with other GRXs from E. coli, S. cerevisiae
and human GRXs. However, ROXY1 and its closest Arabidopsis
homolog At5g14070 belong to the CC type of GRXs, which are specific for higher
plants (Lemaire, 2004). In the
ROXY1 protein, the putative active site is composed of two cysteines (C49 and
C52; Fig. 3A), separated by
another cysteine and methionine (CCMC). Furthermore, these two proteins have
another cysteine in common (C90; Fig.
3A), which could represent (but only for ROXY1), a conserved
N-terminal cysteine of an additional monothiol site (CSGS).
|
Expression pattern of ROXY1
Organ-specific expression of ROXY1 was investigated by RT-PCR,
showing that ROXY1 is strongly expressed in inflorescences, roots and
siliques. Weaker expression was detected in mature flowers, and no expression
was observed in stems and leaves (Fig.
4A). Inflorescence-specific expression was further analyzed by in
situ hybridization. The earliest detectable ROXY1 signal was
localized in the inflorescence apex, delineating the area where future floral
primordia will emerge (pre-stage 1). After formation of young floral primordia
(stage 1; Fig. 4B,C),
ROXY1 expression is restricted to young floral organ primordia (stage
2 and early stage 3). Signal was detected in the areas where sepal primordia
will be initiated (Fig. 4B,C)
and vanishes once sepal primordia start to overgrow the flower primordium
(Fig. 4D). Then, at stage 4 and
5, ROXY1 mRNA appears in the petal and stamen primordia. Again, onset
of expression starts slightly before the respective organ primordia are formed
(Fig. 4D). In early stages,
ROXY1 is expressed throughout the whole petal and stamen primordia.
After onset of stamen differentiation, ROXY1 expression is restricted
to the vascular tissue of these two organs
(Fig. 4E,F) and was also
detected in young ovule primordia (data not shown).
|
Reduction of petal organs in roxy1 mutants is position-dependent
To determine whether the reduction of petal organs in roxy1
mutants is whorl or organ specific, double mutants with class B and C mutants
were constructed. Owing to loss of the class B gene function in the
APETALA3 (AP3) mutant ap3-3, petals are transformed
into sepals and stamens into carpeloid organs or filamentous structures
(Fig. 5A). In the roxy1-3
ap3-3 double mutant, an additive flower phenotype was observed. In the
second whorl, the organ number and size of sepals is reduced and some are
folded inwards, as observed in roxy1-3 single mutants (compare
Fig. 1B with
Fig. 5B). In the class C mutant
ag-1, third whorl stamens are transformed into petals and another
mutant flower is produced in the place of fourth whorl carpels
(Fig. 5C). In the roxy1-3
ag-1 double mutant, the number of second whorl petals is reduced and
their shape altered (Fig.
5D,E). However, petals formed in the third whorl are not affected
in their development, resembling ag-1 third whorl organs.
Additionally, some double mutant flowers produced a secondary flower in the
second whorl, a feature not observed in the single mutants under our growth
conditions (Fig. 5F). Overall,
these data show that ROXY1 exerts its function in a position- and not
organ-dependent mode.
|
|
Genetic interactions with other floral regulatory genes
As our data indicate that ROXY1 is involved in the negative
control of AG expression we tested genetic interactions of
roxy1-3 with two other negative regulators of AG, AP2 and
LUG. Single ap2-5 and lug-1 mutants
(Fig. 7A,C) show premature and
ectopic AG expression (Jofuku et
al., 1994; Liu and Meyerowitz,
1995
), and their phenotypes resemble the roxy1-3 ap1-10
double mutant forming carpeloid first whorl organs. Double mutants of
roxy1-3 with the intermediate ap2-5 and the weak
lug-1 alleles reveal that a lack of the ROXY1 function
strongly enhances single mutant phenotypes. In the roxy1-3 ap2-5
double mutant, first whorl organs are fused at their base and stigmatic
papillae are formed at the tips (Fig.
7B). No petals are formed and occasionally abnormal stamens
develop in the third whorl (data not shown). Similarly, first whorl carpeloidy
is enhanced in the roxy1-3 lug-1 double mutant and rarely second
whorl organs develop (Fig.
7D).
|
The rbe-2 mutant is very similar to the roxy1 mutant, as
its defects are restricted to petal initiation and morphogenesis
(Fig. 7G) (Takada et al.,
2004). Double mutants between roxy1-3 and rbe-2 were
generated to determine whether ROXY1 and RBE function in the
same pathway during petal development. RBE is expressed in petal
precursor cells and petal primordia, overlapping with ROXY1
expression (Takeda et al.,
2004). In roxy1-3 rbe-2 double mutant flowers, instead of
filamentous petals, stamens develop in the second whorl
(Fig. 7H), producing fertile
pollen (data not shown). First whorl organs are not affected. The double
mutant phenotype might correlate with ectopic AG expression,
affecting only the second whorl. As ectopic stamen formation depends on class
B function (Jack et al.,
1997
), it seems that sufficient class B activity either remains in
the roxy1-3 mutant or is enhanced in the double mutant to control,
together with ectopic C function, stamen organogenesis in the second
whorl.
Taken together, double mutant analyses indicate a function for ROXY1 in the temporal and spatial expression regulation of the key floral regulator AG, as all observed organ transformations are probably caused by ectopic class C function. However, double mutants differ with respect to the degree of the ectopic AG function, such that double mutants with ap1-10, ap2-5 and lug-1 indicate AG activity in the first whorl, whereas this activity is restricted to the second whorl in double mutants with ufo-2 and rbe-2.
![]() |
Discussion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
ROXY1: a plant glutaredoxin of the CC type
Sequence analysis revealed that ROXY1 codes for a GRX. GRXs are
small (12 kDa) disulfide oxidoreductases that possess a typical
glutathione-reducible dithiol CXXC or monothiol CXXS active site, required for
the reduction of target protein disulfides. Together with thioredoxins (TRXs),
GRXs form the large thioredoxin superfamily, whose members share one or
several common thioredoxin folds, defined successions of ß-sheets and
-helices (Martin,
1995
). GRXs, like TRXs, may operate as dithiol reductants, and
perform fast and reversible thiol-disulfide exchange reactions between their
active site cysteines and cysteines of their disulfide substrates.
Additionally, GRXs uniquely reduce mixed disulfides in a monothiol mechanism
(Fernandes and Holmgren,
2004
). In most organisms, TRXs and GRXs are the major reducing
molecules, and are involved in many cellular processes. Very recently,
comparative studies including phylogenetic tree analysis were conducted with
oxygenic photosynthetic organisms, comprising Arabidopsis,
Chlamydomonas and Synechocystis. Plant GRXs can be grouped into
three classes that differ in their active site composition
(Lemaire, 2004
;
Rouhier et al., 2004
). In
Arabidopsis, 30 GRX genes have been identified. Six belong to the
classical CPYC type, intensively studied in E. coli and yeast; and
four to the CGFS type that have thus far been analyzed in yeast and humans.
ROXY1, together with 19 other Arabidopsis GRXs, forms a
third and novel CC type group, defined by the presence of CCMC or CCMS motifs.
These GRXs have thus far been identified only in higher plants, suggesting a
specifically evolved function (Lemaire,
2004
). In addition to the 49CCMC52 site, ROXY1 contains
another motif, 90CSGS93, that could represent an active site of the CXXS
monothiol type. To investigate the contribution of the different cysteines to
the ROXY1 function during flower development, site-directed
mutagenesis experiments were carried out. Mutation of C49 to S49 caused a
strongly reduced capacity of the protein to complement the roxy1-3
mutant. Similar results were obtained with E. coli, human and
recently also a poplar GRX, showing that the catalytic cysteine was found to
be located at the N-terminus of the active site
(Foloppe et al., 2001
;
Padilla et al., 1996
;
Rouhier et al., 2002
). Given
that C52 and C90 are less important, our data indicate that C49 might function
in the monothiol pathway, even though it is part of a CCMC motif.
In the monothiol mechanism, GRXs catalyze the reduction of glutathione
(GSH)-mixed disulfides by using only the N-terminal cysteine thiol, a process
known as deglutathionylation (Bushweller et
al., 1992). This reversible mechanism is considered to be the more
general function of GRXs (Fernandes and
Holmgren, 2004
; Cotgreave and
Gerdes, 1998
). However, little is known about glutathionylation of
proteins in photosynthetic organisms. In bacteria, yeast and animal cells,
several proteins have been identified as being glutathionylated, especially in
response to oxidative stress, including chaperones, cytoskeletal proteins,
metabolic enzymes and kinases (Lind et
al., 2002
). Glutathionylation of transcription factors, as shown
for NF-
B and Jun reveals a mechanism for a redox-induced inhibition of
DNA-binding (Pineda-Molina et al.,
2001
; Klatt et al.,
1999
). Our data indicate a novel function of GRXs in flower
development, probably the modification of factors involved in the regulation
of floral organogenesis post-translationally.
ROXY1is the first glutaredoxin shown to play a role in petal development
In roxy1 mutants, petal development is affected at very early and
also during later stages, as revealed by initiating a reduced number of petal
primordia and abnormally bended mature petals. SEM analysis suggests that lack
of primorida initiation does not seem to be caused by a reduced size of the
flower meristem in the area where petal primordia are normally initiated.
Rather, it might be due to a lack of initiation of proper cell divisions
required for primordia outgrowth. Similar phenotypes have been observed in
mutants of the RBE and PTL genes
(Takeda et al., 2004;
Brewer et al., 2004
). Only the
RBE and ROXY1 expression domains overlap in young petal
primordia and second whorl organ number is reduced similarly in the single
mutants and in the double mutant. This suggests that ROXY1 and
RBE might have a common function during second whorl organ
initiation. A combination of both roxy1-3 or rbe-1 with the
class B ap3 mutants results in additive effects, demonstrating that
the function of both genes is organ identity independent. Interestingly, the
RBE protein contains two cysteines in the zinc-finger motif and one further
cysteine close to the C terminus that could represent putative target sites
for modification by ROXY1.
During later petal differentiation, abnormal petal bending was observed in
over 40% of the remaining roxy1 petals, a phenotype not observed in
rbe mutants. The organ identity of folded petals is not altered, as
they still form conical cells typical for adaxial wild-type epidermal cell
layer. Curvature of otherwise flat organs can be caused by deregulation of
cell division processes, as demonstrated by leaf mutant analysis
(Nath et al., 2003). In the
roxy1 mutant, disturbance of cell division regulation could be
responsible for both, lack of primordia initiation at early stages and altered
curvature of petals at later stages. As ROXY1 expression is confined
to the vasculature in older petals, this effect would probably be exerted non
cell-autonomously. Two observations indicate redundancy for the ROXY1
function. First, roxy1 mutants still produce a reduced number of
normal petals. Second, we observed only a defect in the second whorl, although
early ROXY1 expression is not restricted to this whorl. As
ROXY1 belongs to the CC type group of GRXs, which comprises 20 genes,
redundancy could be due to the activity of related proteins. Ectopic
ROXY1 expression does not disturb wild-type flower development
(Fig. 3B), which could be due
to high substrate specificity of ROXY1 and/or lack of ubiquitous target gene
expression.
ROXY1participates in the negative regulation of AG expression in the first and second whorl
Several genes are known to be involved in repression of AG,
including AP2, LUG, SEU, AINTEGUMENTA, STERILE APETALA, BELLRINGER
and CURLY LEAF (Drews et al.,
1991; Conner and Liu,
2000
; Franks et al.,
2002
; Elliott et al.,
1996
; Byzova et al.,
1999
; Bao et al.,
2004
; Goodrich et al.,
1997
). All these genes restrict the expression of AG to
the reproductive organs of the flowers. Occasional formation of filamentous
structures topped with stigmatic papillae in the second whorl of
roxy1 flowers indicated that ROXY1 is an additional
component in this repressive mechanism. This effect is enhanced in double
mutants of roxy1-3 with ap2-5, lug-1 and also
ap1-10, where flowers develop strongly feminized organs in the first
whorl and largely lack second whorl formation. Surprisingly, the influence of
ROXY1 on AG expression is also revealed in combination with
ufo-2 and rbe-2 mutants that do not obviously control
AG activity in single mutants. In roxy1 ufo-2 double mutants
lack of class B activity in the second whorl (due to mutation in UFO)
(Levin and Meyerowitz, 1995
),
along with an ectopic AG activity (due to the lack of ROXY1
function) explains second whorl transformation into carpeloid structures. In
double mutants with rbe-2, enough residual class B activity probably
still resides in the second whorl that causes together with an ectopic
AG activity transformation of second whorl organs into stamens. ROXY1
could participate in AG regulation by modifying its repressors
post-translationally. In fact, GRXs have been shown in animals to
glutathionylate transcription factors and thereby alter their DNA-binding
activity (Pineda-Molina et al.,
2001
; Klatt et al.,
1999
). Recently, also a redox-sensitive plant transcription
factor, TGA1, has been reported, the reduced form of which displays
enhanced DNA-binding during systemic acquired resistance
(Després et al.,
2003
).
![]() |
Conclusion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
![]() |
ACKNOWLEDGMENTS |
---|
![]() |
REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Bao, X., Franks, R. G., Levin, J. Z. and Liu, Z.
(2004). Repression of AGAMOUS by BELLRINGER in
floral and inflorescence meristems. Plant Cell
16,1478
-1489.
Brewer, P. B., Howles, P. A., Dorian, K., Griffith, M. E.,
Ishida, T., Kaplan-Levy, R. N., Kilinc, A. and Smyth, D. R.
(2004). PETAL LOSS, a trihelix transcription factor
gene, regulates perianth architecture in the Arabidopsis flower.
Development 131,4035
-4045.
Bushweller, J. H., Aslund, F., Wuthrich, K. and Holmgren, A. (1992). Structural and functional characterization of the mutant Escherichia coli glutaredoxin (C14S) and its mixed disulfide with glutathione. Biochemistry 31,9288 -9293.[CrossRef][Medline]
Byzova, M. V., Franken, J., Aarts, M. G., de Almeida-Engler, J., Engler, G., Mariani, C., van Lookeren Campagne, M. M. and Angenent, G. C. (1999). Arabidopsis STERILE APETALA, a multifunctional gene regulating inflorescence, flower, and ovule development. Genes Dev. 15,1002 -1014.
Clark, S. E., Running, M. P. and Meyerowitz, E. M.
(1993). CLAVATA1, a regulator of meristem and flower
development in Arabidopsis. Development
119,397
-418.
Clough, S. J. and Bent, A. F. (1998). Floral dip: a simplified method for Agrobacterium-mediated transformation of Arabidopsis thaliana. Plant J. 16,735 -743.[CrossRef][Medline]
Coen, E. S. and Meyerowitz, E. M. (1991). The war of the whorls: genetic interactions controlling flower development. Nature 353,31 -37.[CrossRef][Medline]
Conner, J. and Liu, Z. (2000). LEUNIG,
a putative transcriptional corepressor that regulates AGAMOUS
expression during flower development. Proc. Natl. Acad. Sci.
USA 97,12902
-12907.
Cotgreave, I. A. and Gerdes, R. G. (1998). Recent trends in glutathione biochemistryglutathione-protein interactions: a molecular link between oxidative stress and cell proliferation? Biochem. Biophys. Res. Commun. 242, 1-9.[CrossRef][Medline]
Després, C., Chubak. C., Rochon. A., Clark. R., Bethune,
T., Desveaux, D. and Fobert, P. R. (2003). The Arabidopsis
NPR1 disease resistance protein is a novel cofactor that confers redox
regulation of DNA binding activity to the basic domain/leucine zipper
transcription factor TGA1. Plant Cell
15,2181
-2191.
Drews, G. N., Bowman, J. L. and Meyerowitz, E. M. (1991). Negative regulation of the Arabidopsis homeotic gene AGAMOUS by the APETALA2 product. Cell 14,991 -1002.[CrossRef]
Durfee, T., Roe, J. L., Sessions, R. A., Inouye, C., Serikawa,
K., Feldmann, K. A., Weigel, D. and Zambryski, P. C.
(2003). The F-box-containing protein UFO and AGAMOUS participate
in antagonistic pathways governing early petal development in Arabidopsis.
Proc. Natl. Acad. Sci. USA
100,8571
-8576.
Elliott, R. C., Betzner, A. S., Huttner, E., Oakes, M. P.,
Tucker, W. Q., Gerentes, D., Perez, P. and Smyth, D. R.
(1996). AINTEGUMENTA, an APETALA2-like gene of
Arabidopsis with pleiotropic roles in ovule development and floral organ
growth. Plant Cell 8,155
-168.
Fernandes, A. P. and Holmgren, A. (2004). Glutaredoxins: glutathione-dependent redox enzymes with functions far beyond a simple thioredoxin backup system. Antioxid. Redox Signal. 6,63 -74.[CrossRef][Medline]
Foloppe, N., Sagemark, J., Nordstrand, K., Berndt, K. D. and Nilsson, L. (2001). Structure, dynamics and electrostatics of the active site of glutaredoxin 3 from Escherichia coli: comparison with functionally related proteins. J. Mol. Biol. 310,449 -470.[CrossRef][Medline]
Franks, R. G., Wang, C., Levin, J. Z. and Liu, Z.
(2002). SEUSS, a member of a novel family of plant regulatory
proteins, represses floral homeotic gene expression with LEUNIG.
Development 129,253
-263.
Goodrich, J., Puangsomlee, P., Martin, M., Long, D., Meyerowitz, E. M. and Coupland, G. (1997). A Polycomb-group gene regulates homeotic gene expression in Arabidopsis. Nature 386,44 -51.[CrossRef][Medline]
Griffith, M. E., da Silva Conceicao, A. and Smyth, D. R.
(1999). PETAL LOSS gene regulates initiation
and orientation of second whorl organs in the Arabidopsis flower.
Development 126,5635
-5644.
Gustafson-Brown, C., Savidge, B. and Yanofsky, M. F. (1994). Regulation of the Arabidopsis floral homeotic gene APETALA1. Cell 76,131 -143.[CrossRef][Medline]
Hill, J. P. and Lord, E. M. (1989). Floral development in Arabidopsis thaliana: a comparison of the wild type and the homeotic pistillata mutant. Can. J. Bot. 67,2922 -2936.
Honma, T. and Goto, K. (2001). Complexes of MADS-box proteins are sufficient to convert leaves into floral organs. Nature 409,525 -529.[CrossRef][Medline]
Jack, T., Sieburth, L. and Meyerowitz, E. (1997). Targeted misexpression of AGAMOUS in whorl 2 of Arabidopsis flowers. Plant J. 11,825 -839.[CrossRef][Medline]
Jofuku, K. D., den Boer, B. G., van Montagu, M. and Okamuro, J.
K. (1994). Control of Arabidopsis flower and seed development
by the homeotic gene APETALA2. Plant Cell
6,1211
-1225.
Katz, A., Oliva, M., Mosquna, A., Hakim, O. and Ohad, N. (2004). FIE and CURLY LEAF polycomb proteins interact in the regulation of homeobox gene expression during sporophyte development. Plant J. 37,707 -719.[CrossRef][Medline]
Klatt, P., Molina, E. P., de Lacoba, M. G., Padilla, C. A.,
Martinez-Galesteo, E., Barcena, J. A. and Lamas, S. (1999).
Redox regulation of c-Jun DNA binding by reversible S-glutathionylation.
FASEB J. 13,1481
-1490.
Laufs, P., Coen, E., Kronenberger, J., Traas, J. and Doonan,
J. (2003). Separable roles of UFO during floral
development revealed by conditional restoration of gene function.
Development 130,785
-796.
Lemaire, S. D. (2004). The glutaredoxin family in oxygenic photosynthetic organisms. Photosynthesis Res. 79,305 -318.[CrossRef]
Levin, J. Z. and Meyerowitz, E. M. (1995).
UFO: an Arabidopsis gene involved in both floral meristem and floral
organ development. Plant Cell
7, 529-548.
Lind, C., Gerdes, R., Hamnell, Y., Schuppe-Koistinen, I., von Lowenhielm, H. B., Holmgren, A. and Cotgreave, I. A. (2002). Identification of S-glutathionylated cellular proteins during oxidative stress and constitutive metabolism by affinity purification and proteomic analysis. Arch. Biochem. Biophys. 406,229 -240.[CrossRef][Medline]
Liu, Z. and Meyerowitz, E. M. (1995).
LEUNIG regulates AGAMOUS expression in Arabidopsis flowers.
Development 121,975
-991.
Martin, J. L. (1995). Thioredoxin a fold for all reasons. Structure 3, 245-250.[CrossRef][Medline]
Müller, B. M., Saedler, H. and Zachgo, S. (2001). The MADS-box gene DEFH28 from Antirrhinum is involved in the regulation of floral meristem identity and fruit development. Plant J. 28,169 -179.[CrossRef][Medline]
Nath, U., Crawford, B. C., Carpenter, R. and Coen, E.
(2003). Genetic control of surface curvature.
Science 299,1404
-1407.
Padilla, C. A., Spyrou, G. and Holmgren, A. (1996). High-level expression of fully active human glutaredoxin (thioltransferase) in E. coli and characterization of Cys7 to Ser mutant protein. FEBS Lett. 378,69 -73.[CrossRef][Medline]
Pineda-Molina, E., Klatt, P., Vazquez, J., Marina, A., Garcia de Lacoba, M., Perez-Sala, D. and Lamas, S. (2001). Glutathionylation of the p50 subunit of NF-kappaB: a mechanism for redox-induced inhibition of DNA binding. Biochemistry 40,14134 -14142.[CrossRef][Medline]
Rosso, M. G., Li, Y., Strizhov, N., Reiss, B., Dekker, K. and Weisshaar, B. (2003). An Arabidopsis thaliana T-DNA mutagenized population (GABI-Kat) for flanking sequence tag-based reverse genetics. Plant Mol. Biol. 53,247 -259.[CrossRef][Medline]
Rouhier, N., Gelhaye, E. and Jacquot, J. P. (2002). Exploring the active site of plant glutaredoxin by site-directed mutagenesis. FEBS Lett. 511,145 -149.[CrossRef][Medline]
Rouhier, N., Gelhaye, E. and Jacquot, J. P. (2004). Plant glutaredoxins: still mysterious reducing systems. Cell Mol. Life Sci. 61,1266 -1277.[CrossRef][Medline]
Running, M. P. and Meyerowitz, E. M. (1996).
Mutations in the PERIANTHIA gene of Arabidopsis specifically alter
floral organ number and initiation pattern.
Development 122,1261
-1269.
Schultz, E. A. and Haughn, G. W. (1993).
Genetic analysis of the floral initiation process (FLIP) in Arabidopsis.
Development 119,745
-765.
Sieburth, L. E. and Meyerowitz, E. M. (1997).
Molecular dissection of the AGAMOUS control region shows that
cis elements for spatial regulation are located intragenically.
Plant Cell 9,355
-365.
Smyth, D. R., Bowman, J. L. and Meyerowitz, E. M.
(1990). Early flower development in Arabidopsis. Plant
Cell 2,755
-767.
Takeda, S., Matsumoto, N. and Okada, K. (2004).
RABBIT EARS, encoding a SUPERMAN-like zinc finger protein, regulates
petal development in Arabidopsis thaliana. Development
131,425
-434.
Vlamis-Gardikas, A. and Holmgren, A. (2002). Thioredoxins and glutaredoxin isoforms. Methods Enzymol. 347,286 -296.[CrossRef][Medline]
Wilkinson, M. D. and Haughn, G. W. (1995).
UNUSUAL FLORAL ORGANS controls meristem identity and organ primordia
fate in Arabidopsis. Plant Cell
7,1485
-1499.
Zachgo, S. (2002). In situ hybridization. In Molecular Plant Biology (ed. P. M. Gilmartin and C. Blower), pp. 41-63. Oxford, UK: Oxford University Press.
Zachgo, S., Silva Ede, A., Motte, P., Tröbner, W., Saedler,
H. and Schwarz-Sommer, Z. (1995). Functional analysis of the
Antirrhinum floral homeotic DEFICIENS gene in vivo and in vitro by
using a temperature-sensitive mutant. Development
121,2861
-2875.
|