Lignin is one of the major substance in the world. This slide presented lignin, role in the plant, biosynthesis, lignin evolution, and bioengineering or lignin.
5. Pseudocolor SEM micrograph of lignin redeposited on cellulose (10,000X).
www.nrel.gov/.../technology.cfm/tech=18
6.
7. Lignin:
• Nature’s second abundant organic
substances
• Product of phenylpropanoid
pathway
• Lignin – monolignol/lignin-forming
pathway steps evolved during
transition (evolution) of plants from
the water habitat to the land
habitat.
14. Selaginela
http://esciencenews.com/
Both lignin and cellulose are found in the rigid cell walls of the xylem cells (those that conduct
water) in the primitive plant, Selaginella. (Credit: Zina Deretsky, National Science Foundation;
Selaginella cross section SEM by Jing-Ke Weng, Clint Chapple, Purdue University; Lignin
structure from Wout Bergjan, John Ralph, Marie Baucher (Annual Review of Plant Biology, Vol.
54:519-546, June 2003); Cellulose structure from http://www.chusa.jussieu.fr/disc/bio_cell/)
15. Fossil Ginkgo leaves from the Jurassic of
England. Some 160 million years ago.
Modern Ginkgo leaves.
18. Softwood Hardwood
• Larger, longer cells
• Water transported by cells
• Contains large-diameter vessels
• Water transported by these vessels
19. Lignin: Major monolignols of lignins.
Hatfield R., Vermerris W. Plant Physiol. 2001:126:1351-1357
H-unit
P-hydroxyphenyl
G-unit
guaiacyl
S-unit
syringyl
20. Lignin: Major monolignols of lignins.
(A) Monolignol esters 30-32 found in grasses.
(D) Several dominant
substructures present in
native lignins.
44. Quantification of lignin amounts, lignin degradation protocols, and synthetic
dehydropolymerizates
• Klason Lignin
Various non-lignin
componens, such as tannins,
was determined
• Acetyl bromide
• Thioglycolic acid
53. Lignin, a key component of plant cell
walls, is normally synthesized from
three simple monolignols (top). The
hydroxyl group (OH), shown in red,
must remain unmodified for these
precursors to link up. Liu's team created
a novel enzyme (green "ribbon"
structure) that can methylate this
specific hydroxyl group. This enzyme
may therefore lead to ways to interfere
with lignin biosynthesis in plants to
make them easier to break down for
biofuels.
Chang-Jun Liu
57. Lignin Structure:
Partial structure of a
hypothetical lignin molecule
from European beech (Fagus
sylvatica ). The phenylpropanoid
units that make up lignin are not
linked in a simple, repeating
way. The lignin of beech
contains units derived from
coniferyl alcohol, sinapyl
alcohol, and para-coumaryl
alcohol in the approximate ratio
100:70:7 and is typical of
angiosperm lignin. Gymnosperm
lignin contains relatively fewer
sinapyl alcohol units. (After
Nimz 1974.)
58. Brunow et al. 1998
Lignin Structure: 1990s and 2000s
61. Future Outlook
1. Monolignol transport to the cell/wall
2. Lignin initiation sites
3. Lignin Primary Sequences/New Chemistries
4. Re-oxidation of the growing lignin chains
5. Monolignol radical and lignin primary chain
interactions, proposed template polymerization,
and lignin association
6. Transcriptional control of individual cell wall
formation processes, biomechanics, and
biodegradation of plant cell walls.