共查询到20条相似文献,搜索用时 31 毫秒
1.
Kazuhiko Fukushima 《Journal of plant research》2001,114(4):499-508
p -hydroxyphenyl (H)-, guaiacyl (G)- and syringyl (S) propane, in situ is described. New pathways that regulate the ratio of S to G moieties operating at the stages of cinnamoyl CoA, cinnamyl
aldehyde and cinnamyl alcohol are introduced. The roles of monolignol glucoside in the lignification of tree xylem are discussed.
The results of gene manupulations that alter the lignin structures are also introduced.
Received 15 September 2001/ Accepted in revised form 16 October 2001 相似文献
2.
Incubations of photomixotrophic suspension culture cells of spruce (Picea abies) (L.) (Karst) with an autoclaved cell wall preparation of Rhizosphaera kalkhoffii as elicitor led to a rapid increase of the activity of a number of enzymes involved in lignin biosynthesis. l-phenylalanine ammonia-lyase (EC 4.3.1.5) was induced about 10-fold, feruloyl-Coenzyme A reductase (ED 1.2.1.44) 4-fold, cinnamyl alcohol dehydrogenase (NADP+) (EC 1.1.1.195) 2-fold and peroxidase (EC 1.11.1.7) about 1.5-fold. The induction of the enzymes, with the exception of the peroxidase, was transient, showing maximal activity within 3 days after elicitation. Extracellular peroxidase activity, determined in the culture medium, rapidly decreased on initiation of elicitation.Concomitant with the increase of activity of the enzymes of lignin synthesis was a rapid clouding of the culture medium. Phloroglucinol-HCl staining revealed the presence of lignin-like material in the medium and also in the cells. The IR-spectrum of this material was identical with the IR-spectrum of authentic spruce lignin.Abbreviations PAL
l-phenylalanine ammonia-lyase
- FCR
feruloyl-Coenzyme A reductase
- CAD
cinnamyl alcohol dehydrogenase
- POD
peroxidase 相似文献
3.
Impact of different levels of cinnamyl alcohol dehydrogenase down-regulation on lignins of transgenic tobacco plants 总被引:1,自引:0,他引:1
Nabila Yahiaoui Christiane Marque Kathryn E. Myton Jonathan Negrel Alain Michel Boudet 《Planta》1997,204(1):8-15
The effects of cinnamyl alcohol dehydrogenase (CAD, EC.1.1.1.195) down-regulation on lignin profiles of plants were analysed
in four selected transgenic lines of tobacco (Nicotiana tabacum L. cv. Samsun) exhibiting different levels of CAD activity (8–56% of the control). A significant decrease in thioacidolysis
yields (i.e. yield of β-O-4 linked monomers) and in the ratio of syringyl to guaiacyl monomers (S/G) was observed for three transgenic lines and the
most drastic reduction (up to 50%) was correlated with the lowest level of CAD activity. Higher lignin extractability by mild
alkali treatment was confirmed, and, in addition to a tenfold increase in C6-C1 aldehydes, coniferyl aldehyde was detected by high-performance liquid chromatography in the alkali extracts from the xylem
of transgenic plants. In-situ polymerisation of cinnamyl aldehydes in stem sections of untransformed tobacco gave a xylem
cell wall coloration strikingly similar to the reddish-brown coloration of the xylem of antisense CAD-down-regulated plants.
Overall, these data provide new arguments for the involvement of polymerised cinnamyl aldehydes in the formation of the red-coloured
xylem of CAD-down-regulated plants.
Received: 24 January 1997 / Accepted: 14 May 1997 相似文献
4.
Barakate A Stephens J Goldie A Hunter WN Marshall D Hancock RD Lapierre C Morreel K Boerjan W Halpin C 《The Plant cell》2011,23(12):4492-4506
The manipulation of lignin could, in principle, facilitate efficient biofuel production from plant biomass. Despite intensive study of the lignin pathway, uncertainty exists about the enzyme catalyzing the last step in syringyl (S) monolignol biosynthesis, the reduction of sinapaldehyde to sinapyl alcohol. Traditional schemes of the pathway suggested that both guaiacyl (G) and S monolignols are produced by a single substrate-versatile enzyme, cinnamyl alcohol dehydrogenase (CAD). This was challenged by the discovery of a novel sinapyl alcohol dehydrogenase (SAD) that preferentially uses sinapaldehyde as a substrate and that was claimed to regulate S lignin biosynthesis in angiosperms. Consequently, most pathway schemes now show SAD (or SAD and CAD) at the sinapaldehyde reduction step, although functional evidence is lacking. We cloned SAD from tobacco (Nicotiana tabacum) and suppressed it in transgenic plants using RNA interference-inducing vectors. Characterization of lignin in the woody stems shows no change to content, composition, or structure, and S lignin is normal. By contrast, plants additionally suppressed in CAD have changes to lignin structure and S:G ratio and have increased sinapaldehyde in lignin, similar to plants suppressed in CAD alone. These data demonstrate that CAD, not SAD, is the enzyme responsible for S lignin biosynthesis in woody angiosperm xylem. 相似文献
5.
6.
The tryptophan auxotroph mutant trp3-1 of Arabidopsis thaliana (L.) Heynh., despite having reduced levels of l-tryptophan, accumulates the tryptophan-derived glucosinolate, glucobrassicin and, thus, does not appear to be tryptophan-limited.
However, due to the block in tryptophan synthase, the mutant hyperaccumulates the precursor indole-3-glycerophosphate (up
to 10 mg per g FW). Instability of indole-3-glycerophosphate leads to release of indole-3-acetic acid (IAA) from this metabolite
during standard workup of samples for determination of conjugated IAA. The apparent increase in “conjugated IAA” in trp3-1 mutant plants can be traced back entirely to indole-3-glycerophosphate degradation. Thus, the levels of neither free IAA
nor conjugated IAA increase detectably in the trp3-1 mutant compared to wild-type plants. Precursor-feeding experiments to shoots of sterile-grown wild-type plants using [2H]5-l-tryptophan have shown incorporation of label from this precursor into indole-3-acetonitrile and indole-3-acetic acid with
very little isotope dilution. It is concluded that Arabidopsis thaliana shoots synthesize IAA from l-tryptophan and that the non-tryptophan pathway is probably an artifact.
Received: 1 March 2000 / Accepted: 10 April 2000 相似文献
7.
E. Van der Eycken N. Terryn J. L. Goeman G. Carlens W. Nerinckx M. Claeyssens J. Van der Eycken M. Van Montagu M. Brito-Arias G. Engler 《Plant cell reports》2000,19(10):966-970
Synthesis of five different Sudan-β-d-glucuronides (I, II, III, IV, and RedB) was performed by condensation of a set of red Sudan diazo dyes with methyl (1-deoxy-2,3,4-tri-O-acetyl-1-trichloroacetimidoyl-α-d-glucopyran)uronate. After the acid and alcohol groups had been deprotected, the resulting compounds were used for histochemical
localization of β-glucuronidase (GUS) activity in transgenic plants (Petunia hybrida, Arabidopsis thaliana, and Nicotiana tabacum) that contained the GUS reporter system. Because the cleavage of the β-glucuronide results in the liberation of an insoluble
Sudan dye, Sudan substrates gave no diffusion artifacts as described for the commonly used 5-bromo-4-chloro-3-indolyl-β-d-glucuronide (X-gluc). A comparison of assays with different Sudan glucuronides and X-gluc demonstrated that the SudanIV variant
is a valuable glucuronide substrate for the precise histochemical localization of GUS activity in transgenic plants.
Received: 9 December 1999 / Revision received: 25 January 2000 / Accepted: 26 January 2000 相似文献
8.
Yoshiaki Fujimiya Youichi Suzuki Ko-ichi Oshiman Hidekazu Kobori Koichi Moriguchi Hisako Nakashima Yonezo Matumoto Shogo Takahara Takusaburo Ebina Ryuichi Katakura 《Cancer immunology, immunotherapy : CII》1998,46(3):147-159
We have isolated a novel type of natural tumoricidal product from the basidiomycete strain, Agaricus blazei Murill. Using the double-grafted tumor system in Balb/c mice, treatment of the primary tumor with an acid-treated fraction
(ATF) obtained from the fruit bodies resulted in infiltration of the distant tumor by natural killer (NK) cells with marked
tumoricidal activity. As shown by electrophoresis and DNA fragmentation assay, the ATF also directly inhibited tumor cell
growth in vitro by inducing apoptotic processing; this apoptotic effect was also demonstrated by increased expression of the
Apo2.7 antigen on the mitochondrial membranes of tumor cells, as shown by flow-cytometric analysis. The ATF had no effect
on normal mouse splenic or interleukin-2-treated splenic mononuclear cells, indicating that it is selectively cytotoxic for
the tumor cells. Cell-cycle analysis demonstrated that ATF induced the loss of S phase in MethA tumor cells, but did not affect
normal splenic mononuclear cells, which were mainly in the G0G1 phase. Various chromatofocussing purification steps and NMR
analysis showed the tumoricidal activity to be chiefly present in fractions containing (1→4)-α-D-glucan and (1→6)-β-D-glucan, present in a ratio of approximately 1:2 in the ATF (molecular mass 170 kDa), while the final purified fraction, HM3-G
(molecular mass 380 kDa), with the highest tumoricidal activity, consisted of more than 90% glucose, the main component being
(1→4)-α-D-glucan with (1→6)-β branching, in the ratio of approximately 4:1.
Received: 27 August 1997 / Accepted 22 December 1997 相似文献
9.
Damiani I Morreel K Danoun S Goeminne G Yahiaoui N Marque C Kopka J Messens E Goffner D Boerjan W Boudet AM Rochange S 《Plant molecular biology》2005,59(5):753-769
In angiosperms, lignin is built from two main monomers, coniferyl and sinapyl alcohol, which are incorporated respectively
as G and S units in the polymer. The last step of their synthesis has so far been considered to be performed by a family of
dimeric cinnamyl alcohol dehydrogenases (CAD2). However, previous studies on Eucalyptus gunnii xylem showed the presence of an additional, structurally unrelated, monomeric CAD form named CAD1. This form reduces coniferaldehyde
to coniferyl alcohol, but is inactive on sinapaldehyde. In this paper, we report the functional characterization of CAD1 in
tobacco (Nicotiana tabacum L.). Transgenic tobacco plants with reduced CAD1 expression were obtained through an RNAi strategy. These plants displayed normal growth and development, and detailed biochemical
studies were needed to reveal a role for CAD1. Lignin analyses showed that CAD1 down-regulation does not affect Klason lignin content, and has a moderate impact on G unit content of the non-condensed lignin
fraction. However, comparative metabolic profiling of the methanol-soluble phenolic fraction from basal xylem revealed significant
differences between CAD1 down-regulated and wild-type plants. Eight compounds were less abundant in CAD1 down-regulated lines, five of which were identified as dimers or trimers of monolignols, each containing at least one moiety
derived from coniferyl alcohol. In addition, 3-trans-caffeoyl quinic acid accumulated in the transgenic plants. Together, our results support a significant contribution of CAD1
to the synthesis of coniferyl alcohol in planta, along with the previously characterized CAD2 enzymes.
Sequences of NtCAD1-1 and NtCAD1-7 were deposited in GenBank under accession numbers AY911854 and AY911855, respectively. 相似文献
10.
Upon herbivore attack, maize (Zea mays L.) emits a mixture of volatile compounds that attracts herbivore enemies to the plant. One of the major components of this
mixture is an unusual acyclic C11 homoterpene, (3E )-4,8-dimethyl-1,3,7-nonatriene (DMNT), which is also emitted by many other species following herbivore damage. Biosynthesis
of DMNT has been previously shown to proceed via the sesquiterpene alcohol, (E )-nerolidol. Here we demonstrate an enzyme activity that converts farnesyl diphosphate, the universal precursor of sesquiterpenes,
to (3S)-(E )-nerolidol in cell-free extracts of maize leaves that had been fed upon by Spodoptera littoralis. The properties of this (E )-nerolidol synthase resemble those of other terpene synthases. Evidence for its participation in DMNT biosynthesis includes
the direct incorporation of deuterium-labeled (E )-nerolidol into DMNT and the close correlation between increases in (E )-nerolidol synthase activity and DMNT emission after herbivore damage. Since farnesyl diphosphate has many other metabolic
fates, (E )-nerolidol synthase may represent the first committed step of DMNT biosynthesis in maize. However, the formation of this
unusual acyclic terpenoid appears to be regulated at both the level of (E )-nerolidol synthase and at later steps in the pathway.
Received: 20 August 1999 / Accepted: 27 October 1999 相似文献
11.
Baucher M Bernard-Vailhé MA Chabbert B Besle JM Opsomer C Van Montagu M Botterman J 《Plant molecular biology》1999,39(3):437-447
To improve the digestibility of the forage crop alfalfa (Medicago sativa L.), cinnamyl alcohol dehydrogenase (CAD), which catalyses the last step in the biosynthesis of the lignin monomers, was down-regulated by using an antisense approach. A subset of six transgenic lines with reduced CAD activity and control lines were analysed when grown in the greenhouse and in the field. The down-regulation of the CAD enzyme was associated with a red coloration of the stem. The lignin quantity remained unchanged, but the lignin composition, as determined by thioacidolysis, was altered. The highest reduction of CAD activity was associated with a lower syringyl/guaiacyl (S/G) ratio and a lower S+G yield, mainly because of a decreased amount of S units. An increase in in situ disappearance of dry matter and of cell wall residue was detected in one of the transgenic lines grown in the greenhouse, and for two of the lines grown in the field the rate of disappearance of dry matter slightly improved. Furthermore, these two lines had a higher solubility in alkali as shown by the lower yield of saponified residue. This study opens perspectives for improving forage crop digestibility by the modulation of enzymes involved in lignin biosynthesis. 相似文献
12.
13.
In response to abscisic acid (ABA), the duckweed Spirodela polyrrhiza (L.) activates a developmental pathway that culminates in the formation of dormant structures known as turions. Levels of
the mRNA encoding d-myo-inositol-3-phosphate synthase (EC.5.5.1.4) which converts glucose-6-phosphate to inositol-3-phosphate, increase early in
response to ABA. In order to understand the role of this enzyme in turion formation, we have investigated changes in inositol
metabolism in ABA-treated plants. Here, we show that ABA-treatment leads to a 3-fold increase in free inositol, which peaks
2 d after treatment. This increase is followed by sequential increases in inositol phosphates and in accumulation of inositol
hexakisphosphate (InsP6), in particular. In addition, we observed an early increase in a novel inositol bisphosphate which is not directly on the
pathway to InsP6. In control plants, we observed synthesis and turnover of both inositol pentakisphosphate and InsP6. Two compounds more polar than InsP6 (diphosphoinositol polyphosphates) were present in both ABA-treated and control plants. Together, this suggests that the
role of InsP6 in plants may be more complex than simply that of a storage compound during dormancy.
Received: 10 January 2000 / Accepted: 25 February 2000 相似文献
14.
The xylem of 26-day old Zinnia elegans hypocotyls synthesizes lignins derived from coniferyl alcohol and sinapyl alcohol with a G/S ratio of 43/57 in the aryl-glycerol-beta-aryl ether core, as revealed by thioacidolysis. Thioacidolysis of Z. elegans lignins also reveals the presence of coniferyl aldehyde end groups linked by beta-0-4 bonds. Both coniferyl and sinapyl alcohols, as well as coniferyl and sinapyl aldehyde, are substrates of a xylem cell wall-located strongly basic peroxidase, which is capable of oxidizing them in the absence and in the presence of hydrogen peroxide. This peroxidase shows a particular affinity for cinnamyl aldehydes with kappa(M) values in the mu(M) range, and some specificity for syringyl-type phenols. The affinity of this strongly basic peroxidase for cinnamyl alcohols and aldehydes is similar to that shown by the preceding enzymes in the lignin biosynthetic pathway (microsomal 5-hydroxylases and cinnamyl alcohol dehydrogenase), which also use cinnamyl alcohols and aldehydes as substrates, indicating that the one-way highway of construction of the lignin macromolecule has no metabolic "potholes" in which the lignin building blocks might accumulate. This fact suggests a high degree of metabolic plasticity for this basic peroxidase, which has been widely conserved during the evolution of vascular plants, making it one of the driving forces in the evolution of plant lignin heterogeneity. 相似文献
15.
Increased ethylene evolution accompanies seed germination of many species including Pisum sativum L., but only a little is known about the regulation of the ethylene biosynthetic pathway in different seed tissues. Biosynthesis
of the direct ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), the expression of ACC oxidase (ACO), and ethylene
production were investigated in the cotyledons and embryonic axis of germinating pea seeds. An early onset and sequential
induction of ACC biosynthesis, accumulation of Ps-ACO1 mRNA and of ACO activity, and ethylene production were localized almost exclusively in the embryonic axis. Maximal levels
of ACC, Ps-ACO1 mRNA, ACO enzyme activity and ethylene evolution were found when radicle emergence was just complete. Treatment of germinating
seeds with ethylene alone or in combination with the inhibitor of ethylene action 2,5-norbornadiene showed that endogenous
ethylene regulates its own biosynthesis through a positive feedback loop that enhances ACO expression. Accumulation of Ps-ACO1 mRNA and of ACO enzyme activity in the embryonic axis during the late phase of germination required ethylene, whereas Ps-ACS1 mRNA levels and overall ACC contents were not induced by ethylene treatment. Ethylene did not induce ACO in the embryonic
axis during the early phase of germination. Ethylene-independent signalling pathways regulate the spatial and temporal pattern
of ethylene biosynthesis, whereas the ethylene signalling pathway regulates high-level ACO expression in the embryonic axis,
and thereby enhances ethylene evolution during seed germination.
Received: 28 September 1999 / Accepted: 27 December 1999 相似文献
16.
Microinjection of heme oxygenase genes rescues phytochrome-chromophore-deficient mutants of the moss Ceratodon purpureus 总被引:1,自引:0,他引:1
In protonemal tip cells of the moss Ceratodon purpureus (Hedw.) Brid., phototropism and chlorophyll accumulation are regulated by the photoreceptor phytochrome. The mutant ptr116 lacks both responses as a result of a defect in the biosynthesis of phytochromobilin, the chromophore of phytochrome, at
the point of biliverdin formation. The rescue of the phototropic response and of chlorophyll synthesis were tested by injecting
different substances into tip cells of ptr116. Microinjection was first optimised with the use of fluorescent dyes and an expression plasmid containing a green fluorescent
protein (GFP) gene. Injected phycocyanobilin, which substitutes for phytochromobilin, rescued both the phototropic response
and light-induced chlorophyll accumulation in ptr116. The same results were obtained when expression plasmids with heme oxygenase genes of rat (HO-1) and Arabidopsis thaliana (L.) Heynh. (HY1) were injected. Heme oxygenase catalyses the conversion of heme into biliverdin. Whereas HY1 has a plastid target sequence
and is presumably transferred to plastids, HO-1 is proposed to be cytosolic. The data show that ptr116 lacks heme oxygenase enzyme activity and indicate that heme oxygenases of various origin are active in Ceratodon bilin synthesis. In addition, it can be inferred from the data that the intracellular localisation of the expressed heme
oxygenase is not important since the plastid enzyme can be replaced by a cytosolic one.
Received: 8 March 1999 / Accepted: 30 July 1999 相似文献
17.
Light-induced expression of the Gsa gene encoding the heme and chlorophyll biosynthetic enzyme glutamate 1-semialdehyde aminotransferase in Chlamydomonas reinhardtii was previously shown to involve Ca2+ and calmodulin (CaM) (C. lm et al. 1996, Plant Cell 8: 2245–2253). To further analyze the signal transduction pathway for
light-induced Gsa expression, the effects of several pharmacological agents were examined. Treatment of light-dark synchronized cells with
the heterotrimeric G-protein agonist Mas-7 caused partial induction of Gsa in the dark. The phospholipase C inhibitor U73122 inhibited light induction of Gsa. Exposure of cells to light caused a sustained 3-fold increase in cellular d-inositol 1,4,5-trisphosphate (InsP3) concentration. KN-93, a specific inhibitor of Ca2+/CaM-dependent protein kinase II, inhibited light induction of Gsa. In contrast, cyclosporin A, a specific inhibitor of the Ca2+/CaM-dependent phosphoprotein phosphatase calcineurin, did not affect light induction of Gsa. These results, together with the earlier results, suggest the involvement of a canonical signal transduction pathway for
light-regulated Gsa expression that involves a heterotrimeric G-protein activation, phospholipase C-catalyzed InsP3 formation, InsP3-dependent Ca2+ release, and activation of a downstream signaling pathway through a Ca2+/CaM-dependent protein kinase.
Received: 21 October 1999 / Accepted: 3 December 1999 相似文献
18.
Wood formation in poplar: identification, characterization, and seasonal variation of xylem proteins 总被引:9,自引:0,他引:9
Proteins that are preferentially produced in developing xylem may play a substantial role in xylogenesis. To reveal the identity
of these proteins, comparative two-dimensional polyacrylamide gel electrophoresis was performed on young differentiating xylem,
mature xylem, and bark of poplar (Populus trichocarpa Hook. cv. `Trichobel') harvested at different times of the year. The most-abundant xylem proteins were identified by microsequence
analysis. For 17 of these proteins a putative function could be assigned based on similarity with previously characterized
proteins, and for 15 out of these corresponding expressed sequence tags (ESTs) were found in the poplar EST database. The
identified xylem–preferential proteins, defined by comparing the protein patterns from xylem and bark, were all involved in
the phenylpropanoid pathway: two caffeoyl-coenzyme A O-methyltransferases (CCoAOMT), one phenylcoumaran benzylic ether reductase (PCBER), one bispecific caffeic acid/5-hydroxyferulic
acid O-methyltransferase (COMT), five S-adenosyl-L-methionine synthetases, and one homologue of glycine hydroxymethyltransferase (GHMT). Remarkably, the biological function
of the two most-abundant xylem-preferential proteins (PCBER and a GHMT homologue) remains unclear. In addition, several housekeeping
enzymes were identified: two enolases, two glutamine synthetases, one 70-kDa heat-shock cognate, one calreticulin, and one
α-tubulin. In comparison to the xylem-preferential proteins, the housekeeping proteins were expressed at significant levels
in the bark as well. Also, several additional protein spots were detected for CCoAOMT, PCBER, and COMT by immunoblot. Our
data show that for the study of xylogenesis, two-dimensional protein gel comparisons combined with systematic protein sequencing
may yield information complementary to that from EST sequencing strategies.
Received: 28 June 1999 / Accepted: 3 September 1999 相似文献
19.
Summary. The reactions of Leu- and Met-enkephalin (Tyr-Gly-Gly-Phe-Leu/Met) with fructose resulted in the parallel formation of Heyns
compounds (N-peptidyl-d-mannosamine and -d-glucosamine) and sugar-peptide generated imidazolidinone diastereomers. Glucose showed higher level of reactivity than fructose
with respect to the extent of glycated product formation. The presence of fructose in the incubation mixtures makes Met residue
more susceptible to oxidation than glucose.
Authors’ address: Dr. Štefica Horvat, Division of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, POB 180, 10002
Zagreb, Croatia 相似文献
20.
Infiltrating detached maize (Zeamays L.) leaves with L-galactono-1,4-lactone (L-GAL) resulted in a 4-fold increase in the content of leaf ascorbate. Upon exposure to high irradiance (1000 μmol photons m−2 s−1) at 5 °C, L-GAL leaves de-epoxidized the xanthophyll-cycle pigments faster than the control leaves; the maximal ratio of de-epoxidized
xanthophyll-cycle pigments to the whole xanthophyll-cycle pool was the same in both leaf types. The elevated ascorbate content,
together with the faster violaxanthin de-epoxidation, did not affect the degree of photoinhibition and the kinetics of the
recovery from photoinhibition, assayed by monitoring the maximum quantum efficiency of photosystem II primary photochemistry
(Fv/Fm). Under the experimental conditions, the thermal energy dissipation seems to be zeaxanthin-independent since, in contrast
to the de-epoxidation, the decrease in the efficiency of excitation-energy capture by open photosystem II reaction centers (Fv′/Fm′) during the high-irradiance treatment at low temperature showed the same kinetic in both leaf types. This was also observed
for the recovery of the maximal fluorescence after stress. Furthermore, the elevated ascorbate content did not diminish the
degradation of pigments or α-tocopherol when leaves were exposed for up to 24 h to high irradiance at low temperature. Moreover,
a higher content of ascorbate appeared to increase the requirement for reduced glutathione.
Received: 20 May 1999 / Accepted: 29 October 1999 相似文献