Toshiaki Umezawa

In vivo labeling experiments of Forsythia intermedia plant tissue with [8-14C]- and [9,9-2H2,OC2H3]coniferyl alcohols revealed that the lignans, (-)-secoisolariciresinol and (-)-matairesinol, were derived from two coniferyl alcohol molecules; no evidence for the formation of the corresponding (+)-enantiomers was found. Administration of (+-)-[Ar-3H]secoisolariciresinols to excised shoots of F. intermedia resulted in a significant conversion into (-)-matairesinol; again, the (+)-antipode was not

A lignan, lariciresinol, was isolated from Arabidopsis thaliana, the most widely used model plant in plant bioscience sectors, for the first time. In the A. thaliana genome database, there are two genes (At1g32100 and At4g13660) that are annotated as pinoresinol/lariciresinol reductase (PLR). The recombinant AtPLRs showed strict substrate preference toward pinoresinol but only weak or no activity toward lariciresinol, which is in sharp contrast to conventional PLRs of other plants that can reduc

Lignin is a major component of cell wall biomass and decisively affects biomass utilisation. Engineering of lignin biosynthesis is extensively studied, while lignin modification often causes growth defects. We developed a strategy for cell-type-specific modification of lignin to achieve improvements in cell wall property without growth penalty. We targeted a lignin-related transcription factor, LTF1, for modification of lignin biosynthesis. LTF1 can be engineered to a nonphosphorylation form whi

p-Coumaroyl ester 3-hydroxylase (C3'H) is a key enzyme involved in the biosynthesis of lignin, a phenylpropanoid polymer that is the major constituent of secondary cell walls in vascular plants. Although the crucial role of C3'H in lignification and its manipulation to upgrade lignocellulose have been investigated in eudicots, limited information is available in monocotyledonous grass species, despite their potential as biomass feedstocks. Here we address the pronounced impacts of C3'H deficienc

Both (+)-pinoresinol 6a in Forsythia suspensa and (–)-secoisolariciresinol 14a in F. intermedia are formed via a direct stereochemically-controlled coupling of coniferyl alcohol 2 derived moieties (cf. the typical peroxidase-catalysed reaction in the presence of H2O2), and the dibenzylbutyrolactone lignan, (–)-matairesinol 10a, in F. intermedia is formed from a post-coupling modification of (–)-secoisolariciresinol 14a; this transformation has been demonstrated in vivo, and in vitro with a crude

Lignin is a phenylpropanoid polymer produced in the secondary cell walls of vascular plants. Although most eudicot and gymnosperm species generate lignins solely via polymerization of p-hydroxycinnamyl alcohols (monolignols), grasses additionally use a flavone, tricin, as a natural lignin monomer to generate tricin-incorporated lignin polymers in cell walls. We previously found that disruption of a rice 5-HYDROXYCONIFERALDEHYDE O-METHYLTRANSFERASE (OsCAldOMT1) reduced extractable tricin-type met

Breeding approaches to enrich lignins in biomass could be beneficial to improving the biorefinery process because lignins increase biomass heating value and represent a potent source of valuable aromatic chemicals. However, despite the fact that grasses are promising lignocellulose feedstocks, limited information is yet available for molecular-breeding approaches to upregulate lignin biosynthesis in grass species. In this study, we generated lignin-enriched transgenic rice (Oryza sativa), a mode

Extracellular lignin peroxidase (ligninase) from Phanerochaete chrysosporium catalyzed aromatic ring cleavage of β‐ O ‐4 lignin substructure model dimers to give three esters of arylglycerol, cyclic carbonate, formate and methyl oxalate. H 2 O 2 , was required for the activity of the enzyme.

This investigation examined the aromatic ring cleavage of β‐ O ‐4 lignin substructure model compounds by lignin peroxidase of Phanerochaete chrysosporium . Based on tracer experiments using H 2 18 O and 18 O 2 , mechanisms of the aromatic ring cleavage of the β‐ O ‐4 lignin models were proposed. The mechanisms involve one‐electron oxidation of the β‐ O ‐4 lignin models by the enzyme followed by attack of nucleophiles and radical coupling with O 2 .