Overview: Phenylpropanoids and phenolics are a major biochemical pathway in plants Fig 18.1, 2 Three monolignols (lignin building blocks) Fig 18.7 The Monolignol Biosynthetic Pathway in Vascular Plants
.Light, medium, and dark-gray areas illustrate three levels of aromatic ring modifications that lead to
the biosynthesis of H, G, and S lignin.
Jing-Ke Weng et al. Plant Cell 2011;23:2708-2724
©2011 by American Society of Plant Biologists
II. Key Steps in Monolignol FormaDon Fig 18.2, 4 Hydroxylation and methoxylation of p-coumaric acid
(note - actual substrates occur as esters of shikimate or CoA - refer to whole pathway slide)
Fig 18.2, 4 The Monolignol Biosynthetic Pathway in Vascular Plants
.Light, medium, and dark-gray areas illustrate three levels of aromatic ring modifications that lead to
the biosynthesis of H, G, and S lignin.
Jing-Ke Weng et al. Plant Cell 2011;23:2708-2724
©2011 by American Society of Plant Biologists
III. Lignin Assembly and ComposiDon Fig 18.8 Importance of the CW and general features 5. Secondary CW and lignin Beechwood lignin structure -­‐ note C-­‐C and C-­‐O linkages Bowsher, Plant Biochemistry, 2008
Developmentally-regulated Lignin Synthesis (Stains to visualize lignin)
Phloroglucinol (red) Robinia stem (wood) and Arabidopsis floral stem
Fuchsin stain
– Arabidopsis
vessel element
Mäule reagent (dark = S-lignin) Arabidopsis WT and syringyl mutant
Wood anatomy of transgenic poplar plants
Left = WT, Right = COMT suppressed.
Ruiqin Zhong et al. Plant Physiol. 2000;124:563-578
©2000 by American Society of Plant Biologists
Lignin in Transverse Stem Sections (Fifth Internode) of Control and COMT or CCOMT Antisense Alfalfa.(A)
to (C) Phloroglucinol staining of wild type (empty vector control) (A), antisense COMT line AC310 (B), and
antisense CCOMT line...
wild type
Phloroglucinol
Mäule
Dianjing Guo et al. Plant Cell 2001;13:73-88
©2001 by American Society of Plant Biologists
antisense COMT
antisense CCOMT
Induced lignificaGon in Pinus cell cultures Campbell and Ellis, Planta 184:49 (1992)
Genetic Modification of Lignin in Trees
ii. The effects of down-regulation of 4CL and up-regulation of CAld5H on 4CL and CAld5H
enzyme activities and lignin accumulation and S/G ratio
4CL
Li L et al. PNAS 2003;100:4939-4944
©2003 by The National Academy of Sciences
CAld5H
CAld5H & 4CL
Genetic Modification of Lignin in Trees
iii. 4CL1-1/4CL2-2 RNA transcript levels as measured by qRT-PCR (A), and biomass
of 2-year-old control and transgenic white poplars (B).
Voelker S L et al. Plant Physiol. 2010;154:874-886
©2010 by American Society of Plant Biologists
Genetic Modification of Lignin in Trees
Downregulation of 4-Coumarate CoA Ligase (4CL) in Transgenic Poplar
Phenotypic differences between stems of white poplar control event (A–E) and event 350 (G–K)‫‏‬
CON
Copyright © 2010. © 2010 American Society of Plant Biologists. All rights reserved.
TG 350
Voelker S. L. et.al. Plant Physiol. 2010:154:874-886