|
|
||||||||
|
Plant Physiol. (1998) 118: 1481-1486
Methyl Jasmonate Induces Lauric Acid
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| |
ABSTRACT |
|---|
|
|
|---|
Treatment of etiolated Vicia
sativa seedlings by the plant hormone methyl jasmonate (MetJA)
led to an increase of cytochrome P450 content. Seedlings that were
treated for 48 h in a 1 mM solution of MetJA
stimulated
-hydroxylation of 12:0 (lauric acid) 14-fold compared
with the control (153 versus 11 pmol min
1
mg
1 protein, respectively). Induction was dose dependent.
The increase of activity (2.7-fold) was already detectable after 3 h of treatment. Activity increased as a function of time and reached a
steady level after 24 h. Northern-blot analysis revealed that the
transcripts coding for CYP94A1, a fatty acid
-hydroxylase, had
already accumulated after 1 h of exposure to MetJA and was maximal
between 3 and 6 h. Under the same conditions, a study of the
enzymatic hydrolysis of 9,10-epoxystearic acid showed that both
microsomal and soluble epoxide hydrolase activities were not affected
by MetJA treatment.
Hydroxylases that belong to the CYP4 (Cyt
P450) family and are capable of hydroxylating the terminal
methyl of fatty acids ( Inhibition studies performed in our laboratory suggested the presence
of at least two enzymes capable of fatty acid Jasmonates, which derive from 18:3, are important regulatory molecules
in plant defense (for review, see Sembner and Parthier 1993; Creelman
and Mullet, 1997 We have studied the effect of MetJA on Cyt P450 content and on
Chemicals
![]()
INTRODUCTION
Top
Abstract
Introduction
Methods
Results
Discussion
References
position) have been extensively studied in
mammals (Simpson, 1997
). A remarkable property is their inducibility by
compounds that are known to stimulate peroxisomal proliferation
(Simpson, 1997
). More than 2 decades have passed since the first fatty
acid
-hydroxylation in a plant was described (Soliday and
Kolattukudy, 1977
). Previous investigations from our laboratory have
extensively characterized P450-dependent
-hydroxylases oxidizing C10
to C18 fatty acids in pea and Vicia sativa (Benveniste et
al., 1982
; Salaün et al., 1986
; Pinot et al., 1992
, 1993
). In
V. sativa microsomes, oleic acid is subjected to a cascade
of reactions that involves at least three distinct enzymes: a
peroxygenase, an epoxide hydrolase, and a Cyt P450-dependent
-hydroxylase (Pinot et al., 1992
, 1997
). The latter enzymatic
system, inducible by the peroxisome proliferator clofibrate, is able to
-hydroxylate oleic acid and its oxygenated derivatives,
9,10-epoxystearate and 9,10-dihydroxystearate. The interplay of
the three enzymes accounts for the formation of the major C18 cutin
monomers (Kolattukudy, 1980
). Cutin is a component of the cuticle that
protects plants against different stresses (i.e. pathogens, chemicals,
and drought). It consists of a biopolymer in which monomers are
cross-linked via ester bonds between carboxyl and
-hydroxyl groups.
Thus, enzymes capable of
-hydroxylating fatty acids have a key role in cutin synthesis: by introducing the terminal hydroxyl function, they
allow the elongation reaction of the biopolymer to occur. In addition
to being a constituent of the cuticle,
-hydroxy fatty acids may be
involved in plant defense in another way, because it has been shown
that they act as endogenous signal molecules for the induction of
resistance in pathogen-challenged plants (Schweizer et al., 1996a
,
1996b
).
-hydroxylation in
V. sativa microsomes (Pinot et al., 1993
). This was
confirmed by the recent cloning of distinct
-hydroxylases from
V. sativa (Tijet et al., 1998
; R. Le Bouquin and I. Benveniste, unpublished data). One of these enzymes, CYP94A1, when
expressed in yeast (Tijet et al., 1998
), catalyzed the
-hydroxylation of 18:1, 18:2, and 18:3 (oleic, linoleic, and
linolenic acids, respectively) and of the model substrate 12:0 (lauric
acid).
; Mueller, 1997
). The proteinase inhibitor PI-2 was the
first well-characterized defense-related protein induced by jasmonate
(Farmer and Ryan, 1990
). Gundlach et al. (1992)
studied the induction
of Phe ammonia-lyase, the first enzyme of the phenylpropanoid pathway,
which leads to components of the cell wall and to phytoalexins.
Chalcone synthase, which produces precursors of flavonoids, and
Pro-rich proteins, which participate in cell wall strengthening, are
also induced by MetJA (Creelman et al., 1992
). In
barley jasmonates stimulate the accumulation of JIP5
(jasmonate-inducible proteins),
which have antifungal activity (Andresen et al., 1992
) and JIP60, a
ribosome-inactivating protein (Chaudhry et al., 1994
). Lipoxygenases
take part in the oxylipin pathway, the source of volatile aldehydes,
alcohol, and jasmonates that participate in plant defense (Avdiushko et
al., 1995
). Different studies have demonstrated the induction of
lipoxygenases by jasmonates (Avdiushko et al., 1995
; Heitz et al.,
1997
).
-hydroxylation of the model substrate 12:0 in microsomes of V. sativa seedlings. We investigated the effect of dose and time of
treatment. The expression of CYP94A1 was studied by northern-blot analysis. We also investigated the effect of MetJA treatment on soluble
and microsomal epoxide hydrolase activities. The possible involvement
of CYP94A1 in plant defense is discussed.
![]()
MATERIALS AND METHODS
Top
Abstract
Introduction
Methods
Results
Discussion
References
Plant Material
Vicia sativa seedlings were germinated at 26°C on wet paper with an illumination cycle that consisted of 16 h of light and 8 h of dark (3200 lux). Seedlings were then transferred to distilled water or solutions containing different concentrations of MetJA for various periods (concentrations and periods will be specified for each experiment). To measure the effect of MetJA on Cyt P450 content, seedlings were germinated and induced in water or MetJA in the dark.Preparation of Plant Subcellular Fractions
For each sample 30 g of seedlings was harvested and homogenized with an Ultra-Turrax (15,000 rpm, twice for 30 s; Janke and Kunkel, Staufen i. Br., Germany) in a final volume of 100 mL of 100 mM sodium-phosphate buffer (pH 7.4) containing 250 mM Suc, 40 mM sodium ascorbate, 10 mM
-mercaptoethanol, and 1 mM PMSF. The
homogenate was filtered through 50-µm nylon filtration cloth and centrifuged for 20 min at 10,000g. The resulting
supernatant was centrifuged for 1 h at 100,000g. The
soluble fraction was divided into aliquots and stored at
30°C. To
eliminate contamination from the soluble fraction, the microsomal
pellet was homogenized with a potter in 100 mM
pyrophosphate buffer (pH 7.5) containing 10 mM
-mercaptoethanol. After a second centrifugation at
100,000g, the microsomal pellet was resuspended in 7 mL of
100 mM sodium-phosphate buffer (pH 7.4), 30% (v/v)
glycerol, and 1.5 mM
-mercaptoethanol, divided into
aliquots, and stored at
30°C. Protein concentrations of the
microsomal and soluble fractions were estimated with a microassay from
Bio-Rad using BSA as a standard. Cyt P450 content was measured
according to the method of Omura and Sato (1964)Enzyme Activities
12:0
-Hydroxylase activity was determined by following the rate
of hydroxylated product formation. The standard assay (0.2 mL)
contained 20 mM sodium-phosphate buffer (pH 7.4),
microsomal proteins (approximately 100 µg), 1 mM NADPH,
plus a regenerating system (consisting of final concentration of 6.7 mM Glc-6-P and 0.4 unit of Glc-6-P dehydrogenase), and
radiolabeled substrate (100 µM). The reaction was
initiated by the addition of the NADPH and was stopped after 15 min at
27°C by the addition of 0.1 mL of acetonitrile (0.2% acetic acid).
The reaction products were resolved by TLC as described below. Epoxide
hydrolase activities were measured using 9,10-epoxystearic acid, as
described previously (Pinot et al., 1997Chromatographic Methods
Incubation media were directly spotted on TLC plates, which were developed with a mixture of diethyl ether:light petroleum (boiling point, 40°C-60°C):formic acid (50:50:1, v/v). The plates were scanned with a thin-layer scanner (LB 2723, Berthold Analytical [EG&G Wallac, Gaithersburg, MD]). The area corresponding to the metabolites was scraped into counting vials.Northern-Blot Analysis
Total RNAs were isolated from 15 g of seedlings using the procedure of detergent and phenol-chloroform extraction. For northern-blot analysis, total RNAs (30 µg/lane) were denaturated, subjected to electrophoresis on a 1.2% agarose gel containing formaldehyde, and transferred onto a membrane (Hybond N+, Amersham). The blot was hybridized with 32P-labeled cDNA corresponding to the coding region of CYP94A1 at 65°C for 16 h in 5× SSC. After hybridization, the blot was washed twice with 2× SSC, 0.1% SDS at room temperature for 15 min, and twice with 0.2× SSC, 0.1% SDS at 55°C for 30 min. An 18S ribosomal DNA from radish was used as an internal control. Densitometric quantification of mRNA was performed from scanned autoradiography (Arcus II scanner, Agfa Division, Bayer, Ridgefield Park, NJ) using the NIH-Image program, version 1.59 (National Institutes of Health, Bethesda, MD). The spot-intensity measurement of mRNA was adjusted as a function of the intensity from the internal control (18S ribosomal DNA from radish).| |
RESULTS |
|---|
|
|
|---|
Effect of MetJA on Cyt P450 Content
To investigate the effect of MetJA on Cyt P450 content, 5-d-old V. sativa seedlings were induced in water or in water containing 1 mM MetJA. To avoid synthesis of chlorophyll, which interferes with spectrophotometric measurement of Cyt P450 content, germination and induction were performed in obscurity. The results are presented in Figure 1. Cyt P450 content increased during the first 12 h of induction in microsomes of both control and MetJA-treated seedlings. The level of Cyt P450 was consistently higher in microsomes of treated plants. It is possible that we underestimated the level of jasmonate-induced P450 proteins; indeed, gene regulation sometimes requires illumination.
|
Induction of 12:0
-Hydroxylation
-hydroxy-C12:0 was produced. Furthermore, induction of seedlings for
48 h in a 1 mM solution of MetJA enhanced
-hydroxylation of 12:0 14-fold compared with the control (153 versus
11 pmol min
1 mg
1
protein, respectively).
|
Time Course and Dose Effects
We measured
-hydroxylation of 12:0 in microsomes of seedlings
treated with different concentrations of MetJA. The results are
presented in Figure 3. Even at the lowest
concentration tested (10 µM) the activity was stimulated
by 25% compared with the control. A dose-dependent effect was observed
up to 1 mM MetJA. A direct representation shows that this
response is linear. The limit of dose dependency could be attributable
to aqueous solubility. It could also be attributable to a toxic effect
of MetJA when administered at 5 mM. When treated at this
dose, the seedlings looked unhealthy compared with seedlings treated at
lower doses.
|
Time Course of CYP94A1 Expression in Control and MetJA-Treated
Seedlings
Because we and others (Schweizer et al., 1996a Received June 2, 1998;
accepted September 15, 1998.
Abbreviations:
DEHP, diethylhexyl-phtalate.
MetJA, methyl
jasmonate.
PPAR, peroxisome proliferator-activated receptor.
X:Y, a
fatty acyl group containing X carbon atoms and Y cis
double bonds.
We thank Drs. J.-P. Noël and O. Loreau (Commissariat
á l'Energie Atomique, Gif-sur-Yvette, France) for the generous
gift of [1-14C]9,10-epoxystearic acid.
Andresen I,
Becker W,
Schlüter K,
Burges J,
Parthier B,
Apel K
(1992)
The identification of leaf thionin as one of the main jasmonate-induced proteins of barley.
Plant Mol Biol
19:
193-204
[ISI][Medline]
Avdiushko S,
Croft KPC,
Brown GC,
Jackson DM,
Hamilton-Kemp TR,
Hildebrand D
(1995)
Effect of volatile methyl jasmonate on the oxylipin pathway in tobacco, cucumber, and Arabidopsis.
Plant Physiol
109:
1227-1230
[Abstract]
Benveniste I,
Salaün JP,
Simon A,
Reichhart D,
Durst F
(1982)
Cytochrome P450 dependent
Chaudhry B,
Müller-Uri F,
Cameron-Mills V,
Gough S,
Simpson D,
Skriver K,
Mundy J
(1994)
The barley 60 kDa jasmonate-induced protein (JIP60) is a novel ribosome inactivating protein.
Plant J
6:
815-824
[CrossRef][ISI][Medline]
Creelman RA,
Mullet JE
(1997)
Biosynthesis and action of jasmonates in plants.
Annu Rev Plant Physiol Plant Mol Biol
48:
355-381
[CrossRef][ISI][Medline]
Creelman RA,
Tierney ML,
Mullet JA
(1992)
Jasmonic acid/ methyl jasmonate accumulate in wounded soybean hypocotyls and modulate wound gene expression.
Proc Natl Acad Sci USA
89:
4938-4941
Devchand PR,
Keller H,
Peters JM,
Vazquez M,
Gonzales FJ,
Wahli W
(1996)
The PPAR
Durst F,
Benveniste I
(1993)
Cytochrome P450 in plants.
In
JB Schenkman,
H Greim,
eds, Cytochrome P450: Handbook of Pharmacology, Vol 105.
Springer-Verlag, Berlin, pp 293-310
Farmer EE,
Ryan CA
(1990)
Interplant communication: airborne methyl jasmonate induces synthesis of proteinase in plant leaves.
Proc Natl Acad Sci USA
87:
7713-7716
Forest C,
Franckhauser S,
Glorian M,
Antras-Ferry J,
Robin D,
Robin P
(1997)
Regulation of gene transcription by fatty acids, fibrates and prostaglandins: the phosphoenolpyruvate carboxykinase gene as a model.
Prostaglandins Leukotrienes Essent Fatty Acids
57:
47-56
[Medline]
Forman BM,
Chen J,
Evans R
(1997)
Hypolipidemic drugs, polyunsaturated fatty acids, and eicosanoids are ligands for peroxisome proliferator-activated receptors
Gundlach H,
Muller MJ,
Kutchan T,
Zenk MH
(1992)
Jasmonic acid is a signal transducer in elicitor-induced plant cell cultures.
Proc Natl Acad Sci USA
89:
2389-2393
Heitz T,
Bergey DR,
Ryan CA
(1997)
A gene encoding a chloroplast-targeted lipoxygenase in tomato leaves is transiently induced by wounding, systemin, and methyl jasmonate.
Plant Physiol
114:
1085-1093
[Abstract]
Isseman I,
Green S
(1990)
Activation of a member of the steroid hormone receptor superfamily by peroxisome proliferators.
Nature
347:
645-650
[CrossRef][Medline]
Johnson EF,
Palmer CNA,
Griffin KJ,
Hsu MH
(1996)
Role of the peroxisome proliferator-activated receptor in cytochrome P450 4A gene regulation.
FASEB J
10:
1241-1248
[Abstract]
Kolattukudy PE
(1980)
Biopolyester membranes of plants: cutin and suberin.
Science
208:
990-1000
Krey G,
Braissant O,
L'Horset F,
Kalkhoven E,
Perroud M,
Parker MG,
Wahli W
(1997)
Fatty acids, eicosanoids, and hypolipidemic agents identified as ligands of peroxisome proliferator-activated receptors by coactivator-dependent receptor ligand assay.
Mol Endocrinol
11:
779-791
Mueller MJ
(1997)
Enzymes involved in jasmonic acid biosynthesis.
Physiol Plant
100:
653-663
[CrossRef]
Ohta H,
Suzuki G,
Awai K,
Masuda T,
Kato T,
Shibata D,
Takamiya K
(1997)
Distinct pathways for jasmonate- and elicitor-induced expressions of a cytochrome P450 gene in soybean suspension-cultured cells.
Physiol Plant
100:
647-652
[CrossRef]
Omura T,
Sato R
(1964)
The carbon monoxide binding pigment of liver microsomes. I. Evidence for its hemoprotein nature.
J Biol Chem
239:
2370-2378
Palma JM,
Garrido M,
Rodriguez-Garcia MI,
del Rio LA
(1991)
Peroxisome proliferation and oxidative stress mediated by activated oxygen species in plant peroxisomes.
Arch Biochem Biophys
287:
68-74
[CrossRef][ISI][Medline]
Pinot F,
Bosch H,
Alayrac C,
Mioskowski C,
Vendais A,
Durst F,
Salaün JP
(1993)
Pinot F,
Bosch H,
Salaün JP,
Durst F,
Mioskowski C,
Hammock BD
(1997)
Epoxide hydrolase activities in the microsomes and the soluble fraction from Vicia sativa seedlings.
Plant Physiol Biochem
35:
103-110
Pinot F,
Salaün JP,
Bosch H,
Lesot A,
Mioskowski C,
Durst F
(1992)
Rouster J,
Leah R,
Mundy J,
Cameron-Mills V
(1997)
Identification of a methyl jasmonate-responsive region in the promoter of a lipoxygenase 1 gene expressed in barley grain.
Plant J
11:
513-523
[CrossRef][ISI][Medline]
Salaün JP,
Simon A,
Durst F
(1986)
Specific induction of lauric acid
Schweizer P,
Felix G,
Buchala A,
Müller C,
Métraux JP
(1996a)
Perception of free cutin monomers by plant cells.
Plant J
10:
331-341
Schweizer P,
Jeanguenat A,
Whitacre D,
Métraux JP,
Mösinger E
(1996b)
Induction of resistance in barley against Erysiphe gramini f. sp. hordei by free cutin monomers.
Physiol Mol Plant Pathol
49:
103-120
[CrossRef]
Sembdner G,
Parthier B
(1993)
The biochemistry and the physiological and molecular actions of jasmonates.
Annu Rev Plant Physiol Plant Mol Biol
44:
569-589
[CrossRef][ISI]
Simpson AECM
(1997)
The cytochrome P450 A (CYP4) family.
Gen Pharmacol
28:
351-359
[ISI][Medline]
Soliday CL,
Kolattukudy PE
(1977)
Biosynthesis of cutin.
Stapleton A,
Beetham JK,
Pinot F,
Garbarino JE,
Rockhold DR,
Friedman M,
Hammock BD,
Belknap WR
(1994)
Cloning and expression of soluble epoxide hydrolase from potato.
Plant J
6:
251-258
[CrossRef][Medline]
Suzuki G,
Ohta H,
Kato T,
Igarashi T,
Sakaki F,
Shibata D,
Takano A,
Masuda T,
Shioi Y,
Takamiya K
(1996)
Induction of a novel cytochrome P450 (CYP93 family) by methyl jasmonate in soybean suspension-cultured cells.
FEBS Lett
383:
83-86
[Medline]
Tijet N,
Helvig C,
Pinot F,
Le Bouquin R,
Lesot A,
Durst F,
Salaün JP,
Benveniste I
(1998)
Functional expression in yeast and characterization of a clofibrate-inducible plant cytochrome P450 (CYP94A1) involved in cutin monomer synthesis.
Biochem J
332:
583-589
Wolf G
(1996)
Adipocyte differentiation is regulated by a prostaglandin liganded to the nuclear peroxisome proliferator-activated receptor.
Nutr Rev
54:
290-292
[Medline]
Yang Y,
Shah J,
Klessig DF
(1997)
Signal perception and transduction in plant defense responses.
Genes Dev
11:
1621-1639
-hydroxylation in
microsomes from seedlings induced for different periods in water
(control) or in water containing 1 mM MetJA. The activity
in control microsomes remained constant during the experiment. To the
contrary, induction of seedlings in the presence of 1 mM
MetJA led to a drastic enhancement of activity. The effect of the
inducer was already measurable after 3 h of treatment: activity
was 2.7-fold higher in microsomes of treated plants. Time-course
studies with longer exposure times revealed that activity decreased by
65% between 48 and 72 h (not shown).

View larger version (17K):
[in a new window]
Figure 4.
Effect of time of treatment with MetJA on 12:0
-hydroxylation in microsomes of V. sativa seedlings.
12:0
-Hydroxylation was measured in microsomes of seedlings (5 d
old) induced for different periods in water (
) or in water
containing 1 mM MetJA (
). Data are means ± SD of three measurements performed in duplicate.
-hydroxylase
from V. sativa that hydroxylates C12 to C18 fatty acids
(Tijet et al., 1998
). Here we studied the accumulation of CYP94A1
transcripts during induction of V. sativa seedlings in water
or in water containing 1 mM MetJA. The results are
presented in Figure 5. Hybridization with
a 32P-labeled cDNA probe corresponding to the
whole coding sequence of CYP94A1 showed accumulation of
hydroxylase-specific mRNA after 1 h of exposure to MetJA. The
transcript level increased 14-fold and reached a maximum at 3 h.

View larger version (63K):
[in a new window]
Figure 5.
Time-course analysis of CYP94A1 expression in
control and MetJA-treated V. sativa seedlings. Seedlings
(5 d old) were induced for different periods in water (C) or in water
containing 1 mM MetJA (J). Total RNA was extracted from
15 g of seedlings and 30 µg was subjected to RNA-blot analysis.
An 18S ribosomal DNA from radish was used as an internal standard.
![]()
DISCUSSION
Top
Abstract
Introduction
Methods
Results
Discussion
References
, 1996b
) suspect
that hydroxy fatty acids are involved in stress signaling, we have
examined the effect of the plant hormone MetJA on fatty acid
-hydroxylation. When using a compound such as MetJA, which is both
hydrophobic and volatile, there is no simple relation between the
applied dose and the concentration achieved in situ. We applied MetJA
using the same protocol described previously for hydrophobic compounds
such as clofibrate and DEHP (Salaün et al., 1986
; Pinot et al.,
1992
). A dose-response study (see ``Results'') showed that the
response was clearly detectable from 50 µM and remained
detectable up to 1 mM MetJA in the treatment
solution. It is not possible to directly compare the doses used here
with those used in studies in which MetJA was used in the vapor phase or as droplets on leaves. The majority of our experiments were performed with 1 mM MetJA, the concentration that gave the
highest induction.
). Recently, Suzuki et al. (1996)
and Ohta et al.
(1997)
described the first report of MetJA-induced transcription of a
Cyt P450 gene (CYP93A1) in soybean. The authors suggest that this Cyt
P450 is involved in the plant response to fungal attack.
-hydroxylation of 12:0 was
already 2.7-fold higher in microsomes of treated versus control seedlings. This rapid response is consistent with an involvement of
-hydroxylases in the mechanism of plant defense. When examining the
role of
-hydroxy fatty acids as endogenous signal molecules, Schweizer et al. (1996a)
have shown that they are perceived by potato cells within 1 to 2 h. In other studies related to plant defense, jasmonates accumulated within 2 h after a stress in
cultured cells or in leaves of soybean (Creelman et al., 1992
; Creelman and Mullet, 1997
). These authors also showed that accumulation of mRNA
coding for wound-responsive genes occurred within 4 h after MetJA
treatment.
-hydroxylases are enhanced by compounds
such as clofibrate or DEHP, which induce proliferation of peroxisomes
(for review, see Simpson, 1997
). This enhancement occurs via PPARs.
Isseman and Green (1990)
demonstrated that the first PPAR cloned is
activated by clofibrate and other peroxisome proliferators, which
probably mimic endogenous compounds. Recently, different groups have
shown that PPAR can be activated by prostaglandins and other fatty acid
derivatives, which could be endogenous ligands of PPAR (Devchand et
al., 1996
; Wolf, 1996
; Forest et al., 1997
; Forman et al., 1997
; Krey
et al., 1997
). Clofibrate and DEHP produce similar effects in plants
(Salaün et al., 1986
; Palma et al., 1991
; Pinot et al.,
1992
), which suggests that the mechanisms of regulation by these
compounds may be conserved. There are evident structural analogies
between prostaglandins and jasmonates, which are involved in
responses to stress. Both are cyclic derivatives of fatty acids (20:4
and 18:3, respectively), and they share a similar five-carbon-ringed
structure.
-hydroxylases by prostaglandins, MetJA could induce
-hydroxylase from V. sativa via activation of a transcriptional
regulatory protein analog to PPAR. Recently, Rouster et al. (1997)
identified a MetJA-responsive element in the promoter of a
lipoxygenase. It is interesting that this element contains the motif
TGAC as inverted repeats, which is also found in the promoter region of two mammalian
-hydroxylases, CYP4A1 and CYP4A6 (Johnson et al., 1996
). We are in the process of cloning the complete gene coding for
CYP94A1. The knowledge of the sequence will allow a comparison with
genes inducible by peroxisome proliferators in mammals and genes coding
for proteins implicated in plant defense (Yang et al., 1997
).
). Here we show that MetJA treatment does not affect
microsomal or soluble epoxide hydrolase activities. This is in contrast
to the data from Stapleton et al. (1994)
, who reported induction by
MetJA of the soluble epoxide hydrolase from potato at the
transcriptional level. This discrepancy might be explained by the
existence of different isozymes of epoxide hydrolases. It could also be
attributable to the use of different plant materials. It is noteworthy
that epoxides of fatty acid are more effective stress signals than the
corresponding diols (Schweizer et al., 1996a
). Furthermore, protection
of barley against Erysiphe gramini f. sp. hordei
after application of 9,10-dihydroxystearic acid was not greater than
the protection observed after application of the original epoxide
(Schweizer et al., 1996b
). Finally, secondary hydroxyls resulting from
hydrolysis of an epoxide are not essential for cutin synthesis, which
results from the esterification involving mainly primary hydroxyls
(Kolattukudy, 1980
). Consequently, in the context of plant resistance,
epoxide hydrolases might not have key roles.
-hydroxylation of fatty acids. This
stimulation might be a major event in the general mechanism of plant
defense. It leads to the production of
-hydroxy fatty acids, which
(a) are incorporated in cutin, a constituent of the first barrier
between the plant and the outer environment, and (b) act as endogenous
signals in plants. The comparison of the composition and formation of
cutin in control and MetJA-treated plants will help us to assess the
involvement of
-hydroxylases in cutin synthesis. Furthermore, at
present we are growing tobacco lines (sense and antisense) with coding
sequences of
-hydroxylases. It will be interesting to measure the
cutin formation of these transgenic plants and to determine if cutin
modification alters resistance against stress (i.e. pathogen and
drought). The comparison of mammalian and plant
-hydroxylase
regulation, together with the similar origins, structures, and
functions of prostaglandins and MetJA, suggests that the induction
studied here could involve the activation of a receptor analog to PPAR.
Cloning of the complete gene coding for CYP94A1 might confirm the
existence of cis-elements that could bind such a receptor.
1
This work was partly supported by grants from
the Ministère de la Recherche et de la Technologie
(Génétique et Environnement, no. ACC-SV3) and from the
Centre National de la Recherche Scientifique (Program Environment, no.
GDR 1105).
![]()
FOOTNOTES
*
Corresponding author; e-mail franck.pinot{at}bota-ulp.ustrasbg.fr;
fax 33-3-88-35-84-84.
![]()
ABBREVIATIONS
![]()
ACKNOWLEDGMENTS
![]()
LITERATURE CITED
Top
Abstract
Introduction
Methods
Results
Discussion
References
-hydroxylation of lauric acid by microsomes from pea seedlings.
Plant Physiol
70:
122-126
-leukotriene B4 pathway to inflammation control.
Nature
384:
39-43
[CrossRef][Medline]
and
.
Proc Natl Acad Sci USA
94:
4312-4317
-Hydroxylation of oleic acid in Vicia sativa microsomes. Inhibition by substrate analogs and inactivation by terminal acetylenes.
Plant Physiol
102:
1313-1318
[Abstract]
-Hydroxylation of Z9-octadecenoic, Z9,10-epoxystearic and 9,10-dihydroxystearic acids by microsomal cytochrome P450 systems from Vicia sativa.
Biochem Biophys Res Commun
184:
183-193
[CrossRef][Medline]
-hydroxylase by clofibrate, diethylhexyl-phtalate and 2,4-dichlorophenoxyacetic acid in higher plants.
Lipids
21:
776-779
[CrossRef]
-Hydroxylation of fatty acids by a microsomal preparation from germinating Vicia faba.
Plant Physiol
59:
1116-1121
Copyright Clearance Center: 0032-0889/98/118//06
© 1998 American Society of Plant Physiologists
This article has been cited by other articles:
![]() |
M. Morant, K. Jorgensen, H. Schaller, F. Pinot, B. L. Moller, D. Werck-Reichhart, and S. Bak CYP703 Is an Ancient Cytochrome P450 in Land Plants Catalyzing in-Chain Hydroxylation of Lauric Acid to Provide Building Blocks for Sporopollenin Synthesis in Pollen PLANT CELL, May 1, 2007; 19(5): 1473 - 1487. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Kandel, M. Morant, I. Benveniste, E. Blee, D. Werck-Reichhart, and F. Pinot Cloning, Functional Expression, and Characterization of CYP709C1, the First Sub-terminal Hydroxylase of Long Chain Fatty Acid in Plants: INDUCTION BY CHEMICALS AND METHYL JASMONATE J. Biol. Chem., October 28, 2005; 280(43): 35881 - 35889. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. Duan and M. A. Schuler Differential Expression and Evolution of the Arabidopsis CYP86A Subfamily Plant Physiology, March 1, 2005; 137(3): 1067 - 1081. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. J. W. Watson, J. E. Froehlich, C. A. Josefsson, C. Chapple, F. Durst, I. Benveniste, and R. C. Coolbaugh Localization of CYP86B1 in the Outer Envelope of Chloroplasts Plant Cell Physiol., August 1, 2001; 42(8): 873 - 878. [Abstract] [Full Text] [PDF] |
||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ASPB Publications | PLANT PHYSIOLOGY | THE PLANT CELL | |
|---|---|---|---|