Abiotic and biotic stresses and changes in the lignin ... - ResearchGate

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Figure 1. Biosynthesis pathway of lignin in plants (adapted from Rastogi and Dwivedi,
2008). PAL - phenylalanine ammonia-lyase; C4H - cinnamate 4-hydroxylase; C3H -
cinnamate 3-hydroxylase or p-coumaroyl shikimic acid/quinic acid 3-hydroxylase;
OMT - O-methyltransferase; HCT - p-hydroxy cinnamoyl-CoA: shikimate/quinate p-
hydroxy cinnamoyl transferase; CCoAOMT - caffeoyl coenzyme A O-
methyltransferase; F5H - ferulate 5-hydroxylase; 4CL - 4-coumarate: coenzyme A
ligase; CCR - cinnamoyl coenzyme A reductase; Cald5H - coniferaldehyde 5-
hydroxylase; AldOMT - 5-hydroxy coniferaldehyde O-methyltransferase; SAD -
sinapyl alcohol dehydrogenase; CAD - cinnamyl alcohol dehydrogenase.
Cinnamate
PAL
Phenylalanine
C4H
C3H (?) OMT F5H OMT
4-Coumarate Caffeate Ferulate 5-Hydroxyferulate Sinapate
4CL
4CL 4CL 4CL 4CL (?)
CCoAOM
CCoAOM
HCT
C3H
HCT
COMT F5H (?) COMT
4-Coumaryl-CoA 4-Coumaryl Caffeoyl Caffeoyl-CoA Feruloyl-CoA 5-Hydroxyferuolyl-CoA Sinapyl-CoA
shikimic acid / shikimic acid /
4-Coumaryl
Caffeoyl
CCR
quinic acid
quinic acid
CCR CC CC CC
(?)
OMT F5H OMT
4-Coumaraldehyde Caffeoyl aldehyde Coniferaldehyde 5-Hydroxyconiferaldehyde Sinapaldehyde
CAD/SAD
CAD/SAD CAD/SAD CAD/SAD CAD/SAD
(?) OMT
F5H
OMT
Cald5h
AldOM
4-Coumaryl alcohol Caffeoyl alcohol Coniferyl alcohol 5-Hydroxyconiferyl Sinapyl alcohol
alcohol
p-Hydroxypnehyl Guaiacyl Syringil
(H unit) (G unit) (S unit)
R1 = R2 = H p-coumaryl alcohol (p-hydroxy phenyl, H unit)
R1 = H, R2 = OCH 3 coniferyl alcohol (guayacyl, G unit)
R1 = R2 = OCH 3 sinapyl alcohol (syringyl, S unit)