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81.
82.
Rogers LA Dubos C Surman C Willment J Cullis IF Mansfield SD Campbell MM 《The New phytologist》2005,168(1):123-140
83.
The production of H2 O2 by cucumber hypocotyl segments ( Cucumis sativus L. cv. Wisconsin SMR 58) in response to α-1,4-linked oligomers of galacturonic acid and oligo-β-glucans from the cell walls of Phytophthora megasperma f. sp. glycinea was studied. Oligogalacturonides with degrees of polymerization of 9 to 13 elicited H2 O2 production, the most effective being the deca-, undeca- and dodecamers. A similar relationship between size and effect was previously obtained when oligogalacturonides were tested for their ability to elicit lignification in cucumber hypocotyls. The oligogalacturonide-induced increase in H2 O2 concentration was detected after 4 h, reaching a maximum after 10 h of incubation. The glucan elicitor induced lignification at a 100-fold lower concentration than the oligogalacturonides, but yielded only 10% of the maximum H2 O2 accumulation seen with oligogalacturonides. The glucan elicitor-induced H2 O2 production was detectable after 2 h, and reached a maximum after 4 to 6 h. Catalase abolished the elicitation of both phenol red oxidation and lignification in cucumber hypocotyls. At least part of the oligogalacturonide-induced H2 O2 production appeared to be dependent upon de novo protein synthesis. 相似文献
84.
Distribution of isoflavones in lupin hypocotyls. Possible control of cell wall peroxidase activity involved in lignification 总被引:1,自引:0,他引:1
The distribution of 4 key isoflavones (luteone, genistein, 2'-hydroxygenistein and wighteone) in lupin ( Lupinus albus L. cv. multolupa) hypocotyls shows a gradient that diminishes from young to old tissues. A spatial gradient occurs within the hypocotyl, and a temporal gradient in both the outermost vascular and epidermal tissues. Not only does a gradient exist in respect to the quantity of isoflavones, but there is also a gradient in respect to the type of isoflavone. Thus, wighteone is mainly associated with the non-meristematic zones of the lupin hypocotyl. A close relationship was found between the distribution and the localization in the walls of phloem cells of both peroxidase (EC 1.11.1.7) and isoflavones. This observation suggests an in vivo peroxidase-isoflavone interconnection. In fact, lupin isoflavones are able to inhibit the peroxidase-catalyzed oxidation of the lignin precursor coniferyl alcohol, probably due to the co-oxidation of isoflavones in the reaction media. The results are discussed on the basis of a possible role for isoflavones in controlling cell wallperoxidase activity involved in the lignification of phloem cells. 相似文献
85.
Substrate preferences of O-methyltransferases in alfalfa suggest new pathways for 3-O-methylation of monolignols 总被引:1,自引:0,他引:1
Parvathi K Chen F Guo D Blount JW Dixon RA 《The Plant journal : for cell and molecular biology》2001,25(2):193-202
Measurement of relative O-methyltransferase activities against all potential substrates in the monolignol pathway in developing alfalfa stem extracts revealed activities in the order: caffeoyl CoA > caffeoyl alcohol > 5-hydroxyferulic acid > caffeoyl aldehyde > 5-hydroxyconiferyl alcohol > 5-hydroxyferuloyl CoA > 5-hydroxyconiferaldehyde > caffeic acid. Maxima for all activities occurred in the seventh internode. In stem extracts from transgenic alfalfa with antisense downregulated caffeoyl CoA O-methyltransferase (CCoAOMT), activities with all substrates except for the two coenzyme A esters were unaffected. In contrast, downregulation of caffeic acid O-methyltransferase (COMT) reduced activities against the non-esterifed substrates in the order: 5-hydroxyconiferyl alcohol > 5-hydroxyferulic acid and caffeoyl alcohol > caffeoyl aldehyde > caffeic acid > 5-hydroxyconiferaldehyde. Recombinant COMT expressed in Escherichia coli exhibited the highest V(max)/K(m) values with 5-hydroxyconiferaldehyde and caffeoyl aldehyde, and the lowest with caffeic acid. These results indicate that COMT is unlikely to methylate caffeic acid during lignin biosynthesis in vivo, and provide enzymatic evidence for an alternative pathway to monolignols involving methylation of caffeoyl aldehyde and/or caffeoyl alcohol by COMT. The concept of independent pathways to guaiacyl and syringyl monolignols is discussed. 相似文献
86.
B. Dell 《Plant and Soil》1994,167(2):181-187
A glasshouse experiment was conducted to define the response of Eucalyptus maculata seedlings to the addition of nine rates of copper (Cu) to a Cu-deficient sand. Plants were harvested 128 days from sowing. Symptoms of Cu deficiency included marginal necrosis in young fully expanded leaves (YFEL), deformed leaf margins, death of lateral shoots, bleeding at nodes on the main stem and reduced lignification of xylem fibres and vessels. Plant height and the number of nodes on the main stem were unaffected. In plants supplied with 0 Cu, whole top and root fresh weights were depressed by 27% and 32% respectively. The external Cu requirement for maximum growth of E. maculata seedlings was similar to that for wheat grown in the same soil. In Cu-adequate plants, leaf Cu concentrations decreased with distance from the shoot apex. Cu levels in stems varied little with position and were similar to the YFEL. Cu concentrations in leaves and stems were depressed in Cu-deficient plants to <1.0 g g–1 dry weight (d.w.) (roots: 1.5 g g–1 d.w.). The external Cu supply did not greatly alter the distribution of Cu within the plant. Young leaves at the shoot tip are recommended for diagnosis of Cu deficiency: critical values for shoot d.w. were about 1.5 g Cu g–1 d.w. Lignification of wood was suppressed where Cu concentrations fell below 1.5 g g–1 d.w.: the Bussler test for lignification would thus be a valuable indicator of Cu deficiency. 相似文献
87.
A lucerne (alfalfa, Medicago sativa) stem cDNA library was screened with a cinnamyl-alcohol dehydrogenase (CAD) cDNA probe from tobacco (Nicotiana tabacum cv. Samsun). Two distinctly different cDNA clones (54% identical) were isolated and identified as putative CAD-encoding cDNAs by comparison of their nucleotide sequences with those of CAD-encoding DNA sequences from other plant species. One of the cDNAs, MsaCad2, was found to be 99.4% identical at the nucleotide level to the previously isolated lucerne cad cDNA which encodes a CAD isoform involved in lignin biosynthesis. The other cDNA, MsaCad1, has not been reported previously in lucerne, and encodes a protein related to the ELI3 class of elicitor-inducible defence-related plant proteins. The MsaCad1- and MsaCad2-encoded proteins were expressed in Escherichia coli and CAD1 was shown to be active with a range of cinnamyl, benzyl and aliphatic aldehyde substrates, while CAD2 was specific for the cinnamyl aldehydes only. Each of the respective genes is present as one or two copies. The MsaCad1 gene is expressed most actively in stem and floral tissue, whereas MsaCad2 is most actively expressed in stem, hypocotyl and root tissue. In stem tissue, expression of both genes occurs predominantly in internodes 4 and 5 (from the apex). MsaCad2, in contrast to MsaCad1, is not significantly expressed in the top three internodes of the stem. Both MsaCad1 and MsaCad2 are wound-inducible, and the wound-responsiveness of each gene is modulated by salicylic acid. 相似文献
88.
Vander Mijnsbrugge K Beeckman H De Rycke R Van Montagu M Engler G Boerjan W 《Planta》2000,211(4):502-509
It has previously been shown (D.R. Gang et al., 1999, J Biol Chem 274: 7516–7527) that the most abundant protein in the secondary
xylem of poplar (Populus trichocarpa cv. `Trichobel') is a phenylcoumaran benzylic ether reductase (PCBER), an enzyme involved in lignan synthesis. Here, the
distribution and abundance of PCBER in poplar was studied at both the RNA and protein level. The cellular expression pattern
was determined by immunolocalization of greenhouse-grown plants as well as of a field-grown poplar. Compared to other poplar
tissues, PCBER is preferentially produced in the secondary xylem of stems and roots and is associated with the active growth
period. The protein is present in all cells of the young differentiating xylem, corresponding to the zone of active phenylpropanoid
metabolism and lignification. In addition, PCBER is located in young differentiating phloem fibers, in xylem ray parenchyma,
and in xylem parenchyma cells at the growth-ring border. Essentially the same expression pattern was observed in poplars grown
in greenhouses and in the field. The synthesis of PCBER in phenylpropanoid-synthesizing tissues was confirmed in a bending
experiment. Induction of PCBER was observed in the pith of mechanically bent poplar stems, where phenylpropanoid metabolism
is induced. These results indicate that the products of PCBER activity are synthesized mainly in lignifying tissues, suggesting
a role in wood development.
Received: 28 September 1999 / Accepted: 15 March 2000 相似文献
89.
Dyoni M. Oliveira Thatiane R. Mota Fábio V. Salatta Renata C. Sinzker Radka Končitíková David Kopečný Rachael Simister Mariana Silva Geert Goeminne Kris Morreel Jorge Rencoret Ana Gutiérrez Theodora Tryfona Rogério Marchiosi Paul Dupree José C. del Río Wout Boerjan Simon J. McQueen-Mason Leonardo D. Gomez Osvaldo Ferrarese-Filho Wanderley D. dos Santos 《Plant, cell & environment》2020,43(9):2172-2191
Although cell wall polymers play important roles in the tolerance of plants to abiotic stress, the effects of salinity on cell wall composition and metabolism in grasses remain largely unexplored. Here, we conducted an in-depth study of changes in cell wall composition and phenolic metabolism induced upon salinity in maize seedlings and plants. Cell wall characterization revealed that salt stress modulated the deposition of cellulose, matrix polysaccharides and lignin in seedling roots, plant roots and stems. The extraction and analysis of arabinoxylans by size-exclusion chromatography, 2D-NMR spectroscopy and carbohydrate gel electrophoresis showed a reduction of arabinoxylan content in salt-stressed roots. Saponification and mild acid hydrolysis revealed that salinity also reduced the feruloylation of arabinoxylans in roots of seedlings and plants. Determination of lignin content and composition by nitrobenzene oxidation and 2D-NMR confirmed the increased incorporation of syringyl units in lignin of maize roots. Salt stress also induced the expression of genes and the activity of enzymes enrolled in phenylpropanoid biosynthesis. The UHPLC–MS-based metabolite profiling confirmed the modulation of phenolic profiling by salinity and the accumulation of ferulate and its derivatives 3- and 4-O-feruloyl quinate. In conclusion, we present a model for explaining cell wall remodeling in response to salinity. 相似文献
90.