Lignin Formation in Wheat Coleoptile Cell Walls

Whitmore, F. W.

doi:10.1104/pp.48.5.596

Cited by 26 publications

(23 citation statements)

References 17 publications

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“…A direct role of lignification in the limitation of cell expansion has been evoked only in some rare cases (14,17). The present results, however, do not exclude other cell wall tightening mechanisms capable of controlling cell enlargement.…”

Section: Discussioncontrasting

confidence: 47%

Specific Inhibition of Lignification in Bryonia dioica

Jaegher¹,

Boyer²

1987

Plant Physiol.

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Rubbing-induced lignification in Bryonia dioica internodes is significantly impaired by N(o-hydroxyphenyl) and N(o-aminophenyl) sulfinamoyl tertiobutyl acetate, specific inhibitors of cinamyl alcohol dehydrogenase, an enzyme which is strictly associated with lignin monomer synthesis. Along with the reduction of lignification, these inhibitors counteract the inhibition of elogtion due to rubbing. These results indicate that lignification participates in the thigmomorphogenetic growth response of Bryonia dioica internodes. In a general way, the data point to the causal role of lignification in the limitation of plant growth.Rubbing young internodes of many plants results in growth cessation and increased radial expansion of the internodes (3, 5-9, 15). In Bryonia dioica the reduced elongation has been related to changes in cell wall mechanical properties resulting from an accelerated lignification (9).Several molecules able to reduce lignification have already been defined. Phenylalanine ammonia-lyase is inhibited by aaminooxy-,3-phenylpropionic acid (1) and cinnamate 4-hydroxylase by l-aminobenzotriazole (16). Unfortunately, these two target enzymes are involved in general phenylpropanoid metabolism rather than specifically associated with lignification. In addition, phenylalanine ammonia-lyase inhibitors act also on pyridoxal phosphate enzymes involved in ethylene (10) and amino acid synthesis (2). In contrast, the reductive enzyme cinnamyl alcohol dehydrogenase is strictly associated with the synthesis oflignin monomers and is inhibited in a highly specific way by OHPAS2 and NH2PAS (4,13 The last growing internodes (± 15 mm long) were gently rubbed after 1 d inhibitor feeding. For all analyses internodes were harvested 24 or 48 h after the rubbing treatments. All experiments were repeated at least three times (results ± SE).Lignin Content. Lignin content of cell wall preparations was estimated according to the technique reported before (9). RESULTSRubbing-induced inhibition of internode elongation is significantly counteracted by treatment ofthe plants with OHPAS and NH2PAS, both supplied at the concentration of 40 ,uM (Fig. 1A).Inhibitor feeding at the concentration of 80 AM appeared toxic because of wilting of the plants within 24 h. The slight reducing effect of the inhibitors on elongation of nonrubbed internodes may be a thigmomorphogenetic response due to manipulation ofthe plants. This seems to be confirmed by a concomitant slight increase in lignin content (Fig. 1B). No significant differences

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Section: Discussioncontrasting

confidence: 47%

Specific Inhibition of Lignification in Bryonia dioica

Jaegher¹,

Boyer²

1987

Plant Physiol.

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“…Thus, different CAD isoenzymes, which exhibit different substrate specificities could, potentially, regulate the composition of lignin (Liideritz and Grisebach, 1981). Because of the extremely low amount of lignin present in the young wheat tissues, a qualitative analysis of lignin in wheat coleoptiles is extremely difficult with the present methods (Whitmore, 1971). On the other hand, it can be argued that other enzymes could also potentially regulate the composition of lignin, i.e.…”

Section: Discussionmentioning

confidence: 97%

Multiple Forms of the Constitutive Wheat Cinnamyl Alcohol Dehydrogenase

Pillonel¹,

Hunziker

Binder³

1992

J Exp Bot

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Three cinnamyl alcohol dehydrogenase (CAD) isoenzymes were separated from etiolated wheat seedlings (Triticum aestivum L.) and examined by native gel electrophoresis. Two of these enzymes (CAD-1 and CAD-2) were purified to apparent homogeneity. They exhibited a marked difference in substrate affinity. On sodium dodecyl sulphate-acrylamide gel the isolated isoenzymes showed only one protein band each with an M r 45 000 and 40 000 daltons, respectively, whereas on native gel two bands were identified for each protein. Isoenzymes from a variety of diploid, tetraploid, and hexaploid wheats were compared. The results indicated that the CAD polymorphism could be genetically determined.

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“…Cell wall samples (20 mg) were subject to the nitrobenzene oxidation method of Whitmore (26). Vanillin was localized on TLC plates by spraying with acidic phloroglucinol (0.1% in ethanol).…”

Section: Methodsmentioning

confidence: 99%

Effects of Fungal Elicitor on Lignin Biosynthesis in Cell Suspension Cultures of Soybean

Farmer¹

1985

Plant Physiol.

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Soybean (Glycine max L.) cells cultured in B5 medium produce extremely low amounts of lignin. However, modification in the growth medium, by lowering the concentration of NO-3 and P02;4, results in the lignification of these cells without affecting levels of cell wall-esterified 4-coumaric and ferulic acid. The production of an extracellular, macromolecular complex by the cultured soybean cells (Moore TS Jr 1973 Plant Physiol 51: 529-536 Due to the simplicity of inducing lignin biosynthesis in cultured soybean cells, lack of differentiation in lignifying cells, and the development of a rapid, sensitive lignin detection method, the system described is of use as a model system in the study of the effects of fungal elicitor on the lignin content of the soybean cell wall. Such studies have relevance because it has long been argued that lignin may play an important role in host-pathogen interaction (see review by Vance et al. [25]) for example by acting as a mechanical barrier to pathogen invasion. Many previous studies (reviewed in 25) have failed to distinguish lignin from related hydroxycinnamic acids known to exist in the cell wall (6). Such compounds could play a role in host-pathogen interactions in a similar manner to that proposed for lignin. In the present study, both lignin and cell wall-esterified hydroxycinnamic acids are estimated. Biosynthesis of the former is affected by both the nature of the growth medium and treatment of the soybean cell cultures with fungal elicitor. MATERIALS AND METHODSCell Cultures. Cell suspension cultures of Glycine max L. cv Mandarin were maintained in the dark in B5 growth medium (8) containing 0.05 mM FeSO4-EDTA (15). Cells were subcultured each 6 to 7 d when the conductivity ofthe medium reached 1.5 ± 0.5 mS (9).Medium for the Induction of Lign'ification. B5 medium used to maintain the soybean cells was modified by lowering the levels of two salts, KNO3 and NaH2PO4. H20, without any alteration of hormone concentrations. KNO3 level was lowered from 2.5 g L' (24.7 mM) in B5 medium to 0.94 g L' (9.26 mM) and NaH2PO4.H20 levels lowered from 0.15 g L-' (1.1 mM) in B5 medium to 0.0225 g L-' (0.165 mM). The new medium was designated LSB5 medium.Lignification was induced by transferring cells from B5 to LSB5 medium. In the case of 40-ml cultures, a larger inoculum of cells than was normally used to maintain the culture was transferred to LSB5 medium. Routinely, 7-d-old, 40-ml cell cultures (conductivity, 1.5 ± 0.5 mS) were poured into 400 ml of B5 culture medium in 1 L Erlenmeyer flasks. When this culture had reached conductivity of 1.5 to 2.0 mS, usually between 6 and 7 d, cells were allowed to settle and the spent B5 medium withdrawn under axenic conditions. LSB5 medium (400 ml) was then poured onto the settled cells which were further cultured for 5 to 6 d during which time lignification occurred.

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Lignin Formation in Wheat Coleoptile Cell Walls

Cited by 26 publications

References 17 publications

Specific Inhibition of Lignification in Bryonia dioica

Specific Inhibition of Lignification in Bryonia dioica

Multiple Forms of the Constitutive Wheat Cinnamyl Alcohol Dehydrogenase

Effects of Fungal Elicitor on Lignin Biosynthesis in Cell Suspension Cultures of Soybean

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