Wound-induced deposition of polyphenols in transgenic plants overexpressing peroxidase
TL;DR: Lignin deposition in wounded pith tissue from control plants closely followed the induction of peroxidase activity, however, wound-induced lignification occurred 24 to 48 hours sooner in plants overexpressing the anionic per oxidase.
Abstract: Tobacco (Nicotiana tabacum) plants transformed with a chimeric tobacco anionic peroxidase gene have previously been shown to synthesize high levels of peroxidase in all tissues throughout the plant. One of several distinguishable phenotypes of transformed plants is the rapid browning of pith tissue upon wounding. Pith tissue from plants expressing high levels of peroxidase browned within 24 hours of wounding, while tissue from control plants did not brown as late as 7 days after wounding. A correlation between peroxidase activity and wound-induced browning was observed, whereas no relationship between polyphenol oxidase activity and browning was found. The purified tobacco anionic peroxidase was subjected to kinetic analysis with substrates which resemble the precursors of lignin or polyphenolic acid. The purified enzyme was found to readily polymerize phenolic acids in the presence of H2O2 via a modified ping-pong mechanism. The percentage of lignin and lignin-related polymers in cell walls was nearly twofold greater in pith tissue isolated from peroxidase-overproducer plants compared to control plants. Lignin deposition in wounded pith tissue from control plants closely followed the induction of peroxidase activity. However, wound-induced lignification occurred 24 to 48 hours sooner in plants overexpressing the anionic peroxidase. This suggests that the availability of peroxidase rather than substrate may delay polyphenol deposition in wounded tissue.
Citations
More filters
TL;DR: These studies suggest that pox genes are induced via different signal transduction pathways from those of other known defense-related genes.
Abstract: 3Core Research for Evolutional Science and Technology (CREST), Chiyoda-ku, Tokyo, 101-0062 Japan ; Class III plant peroxidase (POX), a plant-specific oxidoreductase, is one of the many types of peroxidases that are widely distributed in animals, plants and microorganisms. POXs exist as isoenzymes in individual plant species, and each isoenzyme has variable amino acid sequences and shows diverse expression profiles, suggesting their involvement in various physiological processes. Indeed, studies have provided evidence that POXs participate in lignification, suberization, auxin catabolism, wound healing and defense against pathogen infection. Little, however, is known about the signal transduction for inducing expression of the pox genes. Recent studies have provided information on the regulatory mechanisms of wound- and pathogen-induced expression of some pox genes. These studies suggest that pox genes are induced via different signal transduction pathways from those of other known defense-related genes.
826 citations
Cites background from "Wound-induced deposition of polyphe..."
...However, some studies have also indicated possible involvement of TOBPXDLF in lignification or polyphenol metabolism (Lagrimini 1991, Lagrimini et al. 1997a, Klotz et al. 1998), suggesting that this tobacco anionic POX has multiple roles during growth and development in the tobacco plant....
[...]
...Some studies have independently indicated that lignin or suberin content was either increased or unchanged in transgenic plants over- or under-expressing a cer- tain pox gene (Lagrimini 1991, Sherf et al. 1993, Lagrimini et al. 1997a, Mansouri et al. 1999)....
[...]
01 Jun 1998
TL;DR: Molecular investigations of boron nutrition have been initiated by the discovery of a novel mutant of Arabidopsis thaliana with an altered requirement for borOn, which has been implicated in counteracting toxic effects of aluminum on root growth of dicotyledonous plants.
Abstract: ▪ Abstract New and exciting developments in boron research in the past few years greatly contributed to better understanding of the role of boron in plants. Purification and identification of the first boron-polyol transport molecules resolved much of the controversy about boron phloem mobility. Isolation and characterization of the boron-polysaccharide complex from cell walls provided the first direct evidence for boron crosslinking of pectin polymers. Inhibition and recovery of proton release upon boron withdrawal and restitution in plant culture medium demonstrated boron involvement in membrane processes. Rapid boron-induced changes in membrane function could be attributed to boron-complexing membrane constituents. Boron may affect metabolic pathways by binding apoplastic proteins to cis-hydroxyl groups of cell walls and membranes, and by interfering with manganese-dependent enzymatic reactions. In addition, boron has been implicated in counteracting toxic effects of aluminum on root growth of dicotyle...
737 citations
TL;DR: This Update will focus on the levels of control of lignin variation, including (a) metabolic control, (b) regulation of individual enzymes in the biosynthetic pathway, and (c)regulation of gene expression, which affect variation in lignIn content, quality, and distribution.
Abstract: Lignin, a complex phenolic polymer, is important for mechanical support, water transport, and defense in vaseular plants. Compressive strength and hydrophobicity of xylem cell walls are imparted by the lignin polymer, which is deposited during the terminal differentiation of tracheids and other cell types. The resistance of xylem to compressive stresses imposed by water transport and by the mass of the plants is important to growth and development. In addition, the insolubility and complexity of the lignin polymer makes it resistant to degradation by most microorganisms. Therefore, lignin serves an important function in plant defense. Variation in lignin content, composition, and location is likely to affect these essential processes. The constraints on the amount, composition, and localization of lignin for normal xylem function and plant defense are not known. Lignin composition, quantity, and distribution also affect the agroindustrial uses of plant material. Digestibility and dietary conversion of herbaceous crops are affected by differences in lignin content and composition (Akin et al., 1986, 1991). Lignin is an undesirable component in the conversion of wood into pulp and paper; remova1 of lignin is a major step in the paper making process. Furthermore, the resistance of lignin to microbial degradation enhances its persistence in soils. Lignin is, therefore, a significant component in the global carbon cycle. The mechanisms of control of lignin composition and quantity have wide implications regarding the adaptation and evolution of land plants and provide a basis for improved genetic manipulation of lignin for agroindustrial end uses. In this Update, we will focus on the levels of control of lignin variation, including (a) metabolic control, (b) regulation of individual enzymes in the biosynthetic pathway, and (c) regulation of gene expression. These levels of regulation affect variation in lignin content, quality, and distribution. Finally, the implications of these regulatory mechanisms for the genetic improvement of lignin for
634 citations
TL;DR: Populus is presented as a model system for the study of wood formation and high-resolution analysis of auxin distribution across cambial region tissues suggests that auxin provides positional information for the exit of cells from the meristem and probably also for the duration of cell expansion.
Abstract: Populus is presented as a model system for the study of wood formation (xylogenesis). The formation of wood (secondary xylem) is an ordered developmental process involving cell division, cell expansion, secondary wall deposition, lignification and programmed cell death. Because wood is formed in a variable environment and subject to developmental control, xylem cells are produced that differ in size, shape, cell wall structure, texture and composition. Hormones mediate some of the variability observed and control the process of xylogenesis. High-resolution analysis of auxin distribution across cambial region tissues, combined with the analysis of transgenic plants with modified auxin distribution, suggests that auxin provides positional information for the exit of cells from the meristem and probably also for the duration of cell expansion. Poplar sequencing projects have provided access to genes involved in cell wall formation. Genes involved in the biosynthesis of the carbohydrate skeleton of the cell wall are briefly reviewed. Most progress has been made in characterizing pectin methyl esterases that modify pectins in the cambial region. Specific expression patterns have also been found for expansins, xyloglucan endotransglycosylases and cellulose synthases, pointing to their role in wood cell wall formation and modification. Finally, by studying transgenic plants modified in various steps of the monolignol biosynthetic pathway and by localizing the expression of various enzymes, new insight into the lignin biosynthesis in planta has been gained.
466 citations
Cites background from "Wound-induced deposition of polyphe..."
...In contrast, tobacco lines with 10-fold higher peroxidase activities are characterized by a higher lignin content in the leaves, but also by a reduced growth and a browning of wounded tissues (Lagrimini et al., 1990; Lagrimini, 1991)....
[...]
01 Jun 1998
TL;DR: These results argue that the accepted lignin biosynthetic pathway is either incomplete or incorrect, or both; and also suggest that plants may have a high level of metabolic plasticity in the formation of lignins.
Abstract: After a long period of little change, the basic concepts of lignin biosynthesis have been challenged by new results from genetic modification of lignin content and composition. New techniques for making directed genetic changes in plants, as well as improvements in the analytical techniques used to determine lignin content and composition in plant cell walls, have been used in experimental tests of the accepted lignin biosynthetic pathway. The lignins obtained from genetically modified plants have shown unexpected properties, and these findings have extended the known range of variation in lignin content and composition. These results argue that the accepted lignin biosynthetic pathway is either incomplete or incorrect, or both; and also suggest that plants may have a high level of metabolic plasticity in the formation of lignins. If this is so, the properties of novel lignins could be of significant scientific and practical interest.
463 citations
References
More filters
TL;DR: The purification of the anionic peroxidase isozymes from tobacco and their partial amino acid sequence is reported and the messenger for the tobacco isozyme was found to be abundant in stem tissue while expressed at very low levels in leaf and root tissue.
Abstract: Plant peroxidases play a major role in lignin formation and wound healing and are believed to be involved in auxin catabolism and defense to pathogen attack. The function of the anionic peroxidase isozymes is best understood in tobacco. These isozymes catalyze the formation of the lignin polymer and form rigid cross-links between lignin, cellulose, and extensin in the secondary plant cell wall. We report the purification of the anionic peroxidase isozymes from tobacco and their partial amino acid sequence. An oligonucleotide probe deduced from the amino acid sequence was used to screen a tobacco leaf cDNA library and a 1200-base-pair cDNA clone was isolated and sequenced in its entirety. The predicted amino acid sequence revealed a 22-amino acid signal peptide and a 302-amino acid mature protein (Mr, 32,311). The amino acid sequence was compared to that of the cationic peroxidases from horseradish and turnip and was found to be 52% and 46% homologous, respectively. By RNA blot analysis, the messenger for the tobacco isozyme was found to be abundant in stem tissue while expressed at very low levels in leaf and root tissue. Four distinguishable copies of the gene were found on genomic DNA blots. The gene copy number may reflect the allotetraploid nature of Nicotiana tabacum.
407 citations
TL;DR: The present results support the hypothesis that this anionic peroxidase is involved in the deposition of the aromatic polymeric domain of suberin.
Abstract: Thin sections of wound-healing potato tuber tissue were stained with rabbit antibody prepared against a suberization-associated anionic peroxidase and then stained with a goat anti-rabbit antibody-fluorescein conjugate. When these sections were examined with an epiilluminating fluorescence microscope, bright green fluorescent linear deposits were observed on the inner side of cell walls in the periderm layer. Initial deposits which were often not contiguous throughout the wall were first observed in some cells after 3 days of wound-healing and subsequently these layers became more pronounced so that all 6 day old periderm cells had green fluorescent layers on their inner walls. This fluorescence was not present in the walls of parenchyma cells or in the walls of periderm cells treated with preimmune serum and anti-rabbit IgG-FITC conjugate. Thin sections of wound-healing potato tissue which were stained with anti-peroxidase antibody and a goat anti-rabbit antibody-rhodamine conjugate exhibited a similar time course of development with a bright reddish-orange fluorescent layer observed on the inside wall of periderm cells. The production of this suberization-associated anionic peroxidase in wound-healing tissue was also demonstrated by an immunobinding dot blot assay which showed that the largest increase in the enzyme level occurred between 4 and 6 days of wound-healing. The present results support the hypothesis that this anionic peroxidase is involved in the deposition of the aromatic polymeric domain of suberin.
296 citations
TL;DR: To determine which peroxidase isozymes from Nicotiana tabacum are involved in cell wall biosynthesis or other normal cellular functions and which respond to stress, plants were subjected to either wounding or infection with tobacco mosaic virus.
Abstract: Peroxidases (EC 1.11.1.7) have been implicated in the responses of plants to physical stress and to pathogens, as well as in a variety of cellular processes including cell wall biosynthesis. Tissue samples from leaf, root, pith, and callus of Nicotiana tabacum were assayed for specific peroxidase isozymes by analytical isoelectric focusing. Each tissue type was found to exhibit a unique isozyme fingerprint. Root tissue expressed all of the detectable peroxidase isozymes in the tobacco plant, whereas each of the other tissues examined expressed a different subset of these isozymes. In an effort to determine which peroxidase isozymes from Nicotiana tabacum are involved in cell wall biosynthesis or other normal cellular functions and which respond to stress, plants were subjected to either wounding or infection with tobacco mosaic virus. Wounding the plant triggered the expression of several cationic isozymes in the leaf and both cationic and anionic isozymes in pith tissue. Maximum enzyme activity was detected at 72 hours after wounding, and cycloheximide treatment prevented this induction. Infection of tobacco with tobacco mosaic virus induced two moderately anionic isozymes in the leaves in which virus was applied and also systemically induced in leaves which were not inoculated with virus.
275 citations
TL;DR: In soybean seed coats the accumulation of the hydroxyproline-rich glycoprotein extensin is regulated in a developmental and tissue- specific manner and is primarily localized in the seed coat, hilum, and vascular elements of the seed.
Abstract: In soybean seed coats the accumulation of the hydroxyproline-rich glycoprotein extensin is regulated in a developmental and tissue-specific manner. The time course of appearance of extensin during seed development was studied by Western blot analysis and by immunogold-silver localization. Using these techniques extensin was first detected at 16-18 d after anthesis, increasing during development to high levels at 24 d after anthesis. Immunogold-silver localization of extensin in the seed coat showed marked deposition of the glycoprotein in the walls of palisade epidermal cells and hourglass cells. The immunolocalization of extensin in developing soybean seeds was also made by a new technique--tissue printing on nitrocellulose paper. It was found that extensin is primarily localized in the seed coat, hilum, and vascular elements of the seed.
241 citations
TL;DR: A definitive assay for microbiological and biochemical research on the biodegradation of lignin was developed using radioactive synthetic lignins specifically labeled in the side chains, aromatic rings or in the methoxyl groups.
Abstract: A definitive assay for microbiological and biochemical research on the biodegradation of lignin was developed using radioactive synthetic lignins specifically labeled in the side chains, aromatic rings or in the methoxyl groups. The [14C]lignins were prepared by oxidative polymerization with peroxidase and H2O2 Of specifically labeled coniferyl alcohol (4-hydroxy-3-methyoxycinnamyl alcohol). The synthetic polymers were shown by spectroscopic and chemical methods to contain the same intermonomer linkages found in natural lignins. Incubation of the [14C]lignins with known lignin-degrading fungi and with a forest soil resulted in 14CO2 evolution.
205 citations