Recent Advances in Understanding Lignin Biosynthesis

Whetten, Ross; Mackay, John; Sederoff, Ronald R.

doi:10.1146/annurev.arplant.49.1.585

Cited by 426 publications

(287 citation statements)

References 90 publications

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“…Most of the transgenic works have been done in tobacco plants because of the easiness of transformation and the presence of significant amount of second- ary xylem in stems. These studies have demonstrated that not only the lignin content but also the lignin composition can be altered in transgenic plants (Whetten et al, 1998). It has also been shown that alteration of lignin content or composition in transgenic plants could present benefits to reduce pollutions from pulping or increase digestibility of forages (Baucher et al, 1996(Baucher et al, , 1999).…”

Section: Ccoaomt Is An Ideal Target For Genetic Manipulation Of Lignimentioning

confidence: 99%

Essential Role of Caffeoyl Coenzyme A O-Methyltransferase in Lignin Biosynthesis in Woody Poplar Plants

et al. 2000

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Caffeoyl coenzyme A O-methyltransferase (CCoAOMT) has recently been shown to participate in lignin biosynthesis in herbacious tobacco plants. Here, we demonstrate that CCoAOMT is essential in lignin biosynthesis in woody poplar (Populus tremula ϫ Populus alba) plants. In poplar stems, CCoAOMT was found to be expressed in all lignifying cells including vessel elements and fibers as well as in xylem ray parenchyma cells. Repression of CCoAOMT expression by the antisense approach in transgenic poplar plants caused a significant decrease in total lignin content as detected by both Klason lignin assay and Fourier-transform infrared spectroscopy. The reduction in lignin content was the result of a decrease in both guaiacyl and syringyl lignins as determined by in-source pyrolysis mass spectrometry. Fourier-transform infrared spectroscopy indicated that the reduction in lignin content resulted in a less condensed and less cross-linked lignin structure in wood. Repression of CCoAOMT expression also led to coloration of wood and an elevation of wall-bound p-hydroxybenzoic acid. Taken together, these results indicate that CCoAOMT plays a dominant role in the methylation of the 3-hydroxyl group of caffeoyl CoA, and the CCoAOMT-mediated methylation reaction is essential to channel substrates for 5-methoxylation of hydroxycinnamates. They also suggest that antisense repression of CCoAOMT is an efficient means for genetic engineering of trees with low lignin content.

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Section: Ccoaomt Is An Ideal Target For Genetic Manipulation Of Lignimentioning

confidence: 99%

Essential Role of Caffeoyl Coenzyme A O-Methyltransferase in Lignin Biosynthesis in Woody Poplar Plants

et al. 2000

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“…After synthesis and transport to the cell wall these monomers undergo polymerization via an oxidative coupling mechanism. Recent progress in understanding lignin biosynthesis has been reviewed by Baucher et al (1998) and Whetten et al (1998).…”

Section: Introductionmentioning

confidence: 99%

The maize Brown midrib1 locus affects cell wall composition and plant development in a dose-dependent manner

2002

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The four brown midrib (bm) mutants of maize have a reduced content and altered subunit composition of the cell wall polymer lignin. The bm mutations have traditionally been considered completely recessive, because the brown midrib phenotype is only apparent in plants homozygous for the mutation. In addition to an effect on cell wall composition, some bm mutations have been shown to affect flowering time. We had preliminary evidence for a dosage effect of the Bm1 locus on flowering time, which prompted this detailed study on the Bm1 locus. In this study, near-isogenic lines (in an A619 background) with zero, one or two bm1 mutant

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“…4-Coumarate:coenzyme A (CoA) ligase (4CL) mediates activation of hydroxycinnamic acids 4-(p)-coumaric acid (PA), caffeic acid (CA), ferulic acid (FA), 5-hydroxyferulic acid (5HFA), and sinapic acid (SA) into the high-energy intermediates used for biosynthesis of lignin, flavonoids, and various other protective, attractant, and signaling metabolites (Hahlbrock and Scheel, 1989;Dixon and Paiva, 1995;Higuchi, 1997;Whetten et al, 1998). Multiple 4CL isoforms with differential in vitro substrate specificities have been reported in several species (Knobloch and Hahlbrock, 1975;Ehlting et al, 1999), including aspen (Populus tremuloides Michx.…”

mentioning

confidence: 99%

Differential Substrate Inhibition Couples Kinetically Distinct 4-Coumarate:Coenzyme A Ligases with Spatially Distinct Metabolic Roles in Quaking Aspen

et al. 2002

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4-Coumarate:coenzyme A ligase (4CL) activates hydroxycinnamates for entry into phenylpropanoid branchways that support various metabolic activities, including lignification and flavonoid biosynthesis. However, it is not clear whether and how 4CL proteins with their broad substrate specificities fulfill the specific hydroxycinnamate requirements of the branchways they supply. Two tissue-specific 4CLs, Pt4CL1 and Pt4CL2, have previously been cloned from quaking aspen (Populus tremuloides Michx.), but whether they are catalytically adapted for the distinctive metabolic roles they are thought to support is not apparent from published biochemical data. Therefore, single-and mixed-substrate assays were conducted to determine whether the 4CLs from aspen exhibit clear catalytic identities under certain metabolic circumstances. Recombinant Pt4CL1 and Pt4CL2 exhibited the expected preference for p-coumarate in single-substrate assays, but strong competitive inhibition favored utilization of caffeate and p-coumarate, respectively, in mixed-substrate assays. The Pt4CL1 product, caffeoyl-CoA, predominated in mixed-substrate assays with xylem extract, and this was consistent with the near absence of Pt4CL2 expression in xylem tissue as determined by in situ hybridization. It is interesting that the Pt4CL2 product p-coumaroyl-CoA predominated in assays with developing leaf extract, although in situ hybridization revealed that both genes were coexpressed. The xylem extract and recombinant 4CL1 data allow us to advance a mechanism by which 4CL1 can selectively utilize caffeate for the support of monolignol biosynthesis in maturing xylem and phloem fibers. Loblolly pine (Pinus taeda), in contrast, possesses a single 4CL protein exhibiting broad substrate specificity in mixed-substrate assays. We discuss these 4CL differences in terms of the contrasts in lignification between angiosperm trees and their gymnosperm progenitors. 4-Coumarate:coenzyme A (CoA) ligase (4CL) mediates activation of hydroxycinnamic acids 4-(p)-coumaric acid (PA), caffeic acid (CA), ferulic acid (FA), 5-hydroxyferulic acid (5HFA), and sinapic acid (SA) into the high-energy intermediates used for biosynthesis of lignin, flavonoids, and various other protective, attractant, and signaling metabolites (Hahlbrock and Scheel, 1989; Dixon and Paiva, 1995;Higuchi, 1997;Whetten et al., 1998). Multiple 4CL isoforms with differential in vitro substrate specificities have been reported in several species (Knobloch and Hahlbrock, 1975;Ehlting et al., 1999), including aspen (Populus tremuloides Michx.; Hu et al., 1998), and these isoforms have been proposed to control the relative abundance of flavonoids and various lignin precursors (monolignols) during structural, protective, and reproductive development (Ranjeva et al., 1976;Knobloch and Hahlbrock, 1977;Grand et al., 1983). Wounding, UV light, and elicitors increase transcript abundance of different 4CL isoforms (Uhlmann and Ebel, 1993;Ehlting et al., 1999), reinforcing the model that there are distinct associations be...

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Recent Advances in Understanding Lignin Biosynthesis

Cited by 426 publications

References 90 publications

Essential Role of Caffeoyl Coenzyme A O-Methyltransferase in Lignin Biosynthesis in Woody Poplar Plants

Essential Role of Caffeoyl Coenzyme A O-Methyltransferase in Lignin Biosynthesis in Woody Poplar Plants

The maize Brown midrib1 locus affects cell wall composition and plant development in a dose-dependent manner

Differential Substrate Inhibition Couples Kinetically Distinct 4-Coumarate:Coenzyme A Ligases with Spatially Distinct Metabolic Roles in Quaking Aspen

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