Transcriptional Regulation of the Lignin Biosynthetic Pathway Revisited: New Players and Insights - Botanical Research - page 203

Gene Expression and transgenic phenotype Function and target genes References

TaMYB4; T. aestivum Highly expressed in stems and root tissues.

OE in tobacco shows decrease of total
lignin but increase in S/G ratio. Also
increases the total flavonoid content.

Negative regulator of the lignin
pathway. Downregulates CCR and
CAD.

Ma et al. (2011)

PvMYB4; P. virgatum Highest expression in vascular bundles of

leaves and sheaths. OE in transgenic
switchgrass resulted in reduced lignin
content and ester-linked p-coumaric acid/
ferulic acid ratio.

Repressor of monolignol pathway.
Binds to the AC-I, AC-II and AC-III
elements of monolignol pathway
genes and downregulates these genes
in vivo.

Shen et al. (2012)

AtMYB75/PAP1;
A. thaliana

Expressed in young emerging leaf tissue/
primordial. Activation tagging mutant
increases lignin- and wall-bound
hydroxycinnamic esters, flavonols and
anthocyanins.

Activator of phenylpropanoid genes.
Enhance expression of PAL,
chalcone synthase (CHS), DFR and
glutathione transferase (GST).

Borevitz et al.
(2000) , Tohge
et al. (2005)

AtMYB75/PAP1;
A. thaliana

KO mutant increases cell wall thickness in
xylary and IF. Upregulates lignin
biosynthesis, cellulose deposition and SW
modifying enzymes.

Repressor of the lignin branch of the
phenylpropanoid. Interacts with
KNAT7. In KO-lines, increases
expression for lignin genes (PAL,
C4H, 4CL, HCT, CCoAOMT, F5H)
and also CesA4, CesA7, Cesa8,
IRX8 and IRX9.

Bhargava et al.
(2010)

AtWRKY12; A. thaliana Expressed in pith and cortex of stems, but

not in roots. KO mutant shows SW
thickening only in pith associated with
ectopic deposition of lignin, xylan and
cellulose (50% increase of biomass).

Negative regulator of SW. Direct
binding of NAC (NST2) Cys3His
zing finger.

Wang et al. (2010)

NtLIM1; N. benthamiana Transgenic tobacco and E. camaldulensis

plants carrying an antisense NtLIM1
showed a reduction of 27-29% of their
lignin content.

Binds to the PAL-box motif of the
promoter of a horseradish C2
peroxidase (prxC2) gene. Decreases
expression of PAL and 4CL.

Kaothien et al.
(2002) , Kawaoka
and Ebinuma
(2001) , Kawaoka
et al. (2000; 2007)