Studies on the Biosynthesis of Lignins

Abstract

Freudenberg et at (t952) demonstrated the polymerization of coniferyl atcotiol in tbe presence of oxidizing enzymes from Araucaria. Addition of bydrogen peroxide increased tbe yietd of polymer, and tbe presence of peroxidase in tbe enzyme preparation was indicated.Siegel (1953) reported tbat eugenol, incubated witb tissues of tbe Red Kidney bean embryo, was converted into a lignin-bke material wben peroxide was supplied in tbe reaction mixture. Cbaracteristic lignin color reactions were obtained and tbe product was isolated in measurable quantities by standard procedures used in lignin determination (Norman, 1937).Formation of lignin from eugenol was rapid (2.5-5.0 mg./lOO mg. dry matter in 3 bours), HaOg-dependent, and effected by a cyanide-inbibited tbermolabile catalyst. Tbe obvious interpretation, tbat tbe enzyme peroxidase participated in tbe lignin-forming process, was supported by agreement between sites of intense deposition of tbe presumptive lignin and tbose of bigb peroxidase activity (fibrovascular ring, meristems).It was subsequently observed tbat sections from internodes of Elodea densa were bigbly active in converting eugenol into lignin; tbat substances otber tban eugenol and tbymol serve as lignin precursors, and tbat tbe properties of tbe material formed almost certainly place it witb naturally occurring lignins. '• Present address:

Lignification during Heartwood Formation: Comparative Study of Rays and Bordered Pit Membranes in Coniferous Woods

“…That means contrary to the hypothesis of Siegel (1954), that secondary transformations in lignification do not necessarily take place only in the cytoplasm, but also in the cell wall and pit membranes. A selective incorporation of 14 C-coniferin was successful in walls of ray parenchyma cells of green wood, but not in bordered pit membranes (Fig.…”

Differential Activity of Peroxidase Isozymes in Response to Wounding, Gypsy Moth, and Plant Hormones in Northern Red Oak (Quercus rubra L.)

“…PODs comprise one important class of PR proteins (PR-9) implicated in these "defense responses," in which an important role is to catalyze the formation of phenolic radicals at the expense of H 2 O 2 (Gaspar et al, 1985). PODs may also oxidize phenolic monomers to form lignin (Siegel, 1954;Mäder et al, 1980;Grisebach, 1981), function in H 2 O 2 production (Elstner and Heupel, 1976;Mäder et al, 1980), and metabolize indole acetic acid (Endo, 1968;Mato et al, 1988). Each plant species typically displays a unique pattern and number of soluble and wall-bound isozymes that may respond differentially to environmental stimuli.…”

Comparison of Lignin-like Products Found Naturally or Induced in Tissues of Phleum, Elodea, and Coleus, and in a Paper Perioxidase System

“…The residue was washed several times with Except for differences in solubility of the product in NaHCO3 and in the production of phloroglucinol reacting groups, these lignins induced in several different systems are strikingly similar when analyzed by the techniques devised for grasses. As has been shown by others (9,16), peroxidase is able to oxidize a variety of compounds, the products of which are known to polymerize. It is of particular interest that the 3 acids related to the alcohols postulated as the substrates normally polymerized in woody tissues (3,6) produce products characteristic of the acid itself rather than of its aldehyde or alcohol.…”