Phenylpropanoid biosynthesis in plants engenders a myriad of aromatic
compounds that possess diverse biological functions essential for the
plant’s growth, development, and its interactions with the environment. In
particular, the heterogeneous aromatic polymer lignin, as a structural
component that impregnates the polysaccharide-based cell walls, imparts
strength, rigidity, and water impermeability to plant vasculature, assuring
the conductance of water and nutrients. Lignified secondary cell walls
represent the bulk biomass of terrestrial plants, and are the most abundant
renewable raw materials for pulping and paper making, and for producing
bio-based chemicals and biofuels. However, the presence of intractable
lignin in the cell walls is a formidable obstacle in assuring our efficient
utilization of cellulosic fibers; in particular, it impedes the enzymatic
release of simple sugars from the cell walls’ polysaccharides, thus lowering
the fermentative production of renewable biofuels. In addition to lignin,
many soluble phenolics, synthesized in a species-specific manner, act as
anti-pathogenic phytoalexins, antioxidants, or UV-absorbing compounds,
protecting plants from biotic and abiotic stresses. Importantly, an array of
these phenolics and polyphenolics have been demonstrated to possess
considerable pharmacological activities that are potentially beneficial for
The central research interest in our group focusses on understanding the
biosynthesis and metabolic regulation of plant phenylpropanoids,
particularly, those phenolics incorporated into cell walls (i.e., lignin and
the "wall-bound" phenolics). We will direct our researches to addressing the
following problems: How lignin and the "wall-bound" phenolics are
synthesized and incorporated into the cell walls; how these processes are
regulated; and how their incorporation affects the ultrastructure and
functions of the cell walls. Ultimately we anticipate applying our knowledge
to develop effective strategies to manipulate the synthesis and deposition
of phenolics in the cell walls, thereby lowering the recalcitrance of the
lignocellulosic biomass for a more efficient and sustainable production of
biofuels and bio-based chemicals.
Through the integrated approaches of biochemistry, molecular genetics,
structural biology, and protein engineering, our group is conducting four
lines of research: 1) Exploring the molecular mechanisms of
post-translational regulation, and the macromolecular organization of
phenylpropanoid-lignin biosynthesis; 2) Deciphering the molecular mechanisms
of deposition or sequestration of lignin precursors and the “wall-bound”
phenolics; 3) Employing X-ray crystallographic strategies to study the
structure-function of the key enzymes in the phenylpropanoid pathways, and
using the structural information obtained to design and create novel enzymes
to modulate phenylpropanoid-lignin biosynthesis; and, 4) Characterizing the
key enzymes and regulatory elements involved in synthesizing the
In the News
- Zhang X., Gou M., Guo C. R., Yang H., Liu C.-J.
Down-regulation of kelch domain-containing F-box protein in Arabidopsis
enhances the production of (poly)phenols and tolerance to UV-radiation.
Plant Physiology 167: 337–350 (2015)
- Zhang X. and Liu C.-J.
regulations of gateway enzyme phenylalanine ammonia-lyase in the biosynthesis of
Molecular Plant 8:17-27 (2015)
- Liu C.-J., Cai Y.-H., Zhang X., Gou M., Yang H.
Tailoring lignin biosynthesis for efficient and
sustainable biofuel production.
Plant Biotechnology Journal 12(9):1154-62 (2014)
- Zhang K., Novak O., Wei Z., Gou M., Zhang X., Yu Y., Yang H., Cai Y., Strnad M., and Liu C.-J.
Arabidopsis ABCG14 protein controls the acropetal translocation of root-synthesized cytokinins.
Nature Communications, 5:3274 (2014).
- Xu B., Gou J.-Y., Li F.G., Shangguan X.X., Zhao B., Yang C.Q., Wang L.J., Yuan S., Liu C.-J., and Chen X.Y.
A cotton BURP domain protein interacts with α-expansin and their co-expression promotes plant growth
and fruit production.
Molecular Plant, 6(3):945-958 (2013).
- Zhang K., Halitschke R., Yin C., Liu C.-J., and Gan S.S. Salicylic acid 3-hydroxylase regulates
Arabidopsis leaf longevity by mediating salicylic acid catabolism.
Proc. Natl. Acad. Sci. USA,
- Zhang X., Gou M., and Liu C.-J. Arabidopsis kelch repeat F-box proteins regulate phenylpropanoid
biosynthesis via controlling the turnover of phenylalanine ammonia-lyase. The Plant Cell, 25(12):4994-5010
- Cheng A.X., Gou J.Y., Yu X.H., Yang H., Fang X., Chen X.Y.,and Liu C.J.
Characterization and ectopic expression of a Populus hydroxyacid hydroxycinnamoyltransferase.
Mol. Plant, 6(6):1889-1903 (2013).
- Rimando A.M., Pan Z., Polashock J.J., Dayan F.E., Mizuno C.S., Snook M.E.,
Liu C.-J., and Baerson S.R. In planta production of the highly potent resveratrol
analogue pterostilbene via stilbene synthase and O-methyltransferase co-expression.
Plant Biotech. J., 10(3):269-283 (2012).
- Zhang K., Bhuiya M.W., Pazo J.R., Miao Y., Kim H., Ralph J., and Liu C.-J.
An engineered monolignol 4-O-methyltransferase depresses lignin biosynthesis
and confers novel metabolic capability in Arabidopsis.
Plant Cell, 24(7):3135-3152 (2012).
Gou J.Y., Miller L.A., Hou G., Yu X.-H., Chen X.-Y. and Liu C.-J.
Acetylesterase-mediated deacetylation of pectin impairs cell elongation,
pollen germination, and plant reproduction.
Plant Cell, 24(1):50-65 (2012).
Deciphering the enigma of lignification: Precursor transport, oxidation, and the
topochemistry of lignin assembly.
Mol. Plant, 5(2):304–317 (2012).
Manjasetty B.A., Yu X.-H., Panjikar S., Taguchi G., Chance M.R. and Liu C.-J.
Structural basis for modification of flavonol- and naphthol-glucoconjugates by
Nicotiana tabacum malonyltransferase (NtMaT1).
Planta, 236(3):781–793 (2012).
Zhang K.W., Bhuiya M.W., Pazo J.R., Miao Y., Kim H., Ralph J. and Liu C.-J.
An engineered monolignol 4-O-methyltransferase Depresses lignin polymerization and confers novel metabolic capability in Arabidopsis.
Plant Cell 24(7):3135-3152 (2012).
Gou J.Y., Felippes F.F., Liu C.-J., Weigel D. and Wang J.W.
Negative Regulation of Anthocyanin Biosynthesis in Arabidopsis by a miR156-Targeted SPL Transcription Factor.
Plant Cell, 23(4):1512-1522 (2011).
Liu C.-J., Miao Y.C. and Zhang K.W.
Sequestration and transport of lignin monomeric precursors.
Molecules, 16(1):710-727 (2011).
Bhuiya M.W. and Liu C.-J.
Engineering monolignol 4-O-methyltransferases to modulate lignin biosynthesis.
J. Biol. Chem., 285(1):277-285 (2010).
Biosynthesis of hydroxycinnamate conjugates: Implications for sustainable biomass and biofuel production.
Biofuels, 1(5):745-761 (2010).
Miao Y.-C. and Liu C.-J.
ATP-binding cassette-like transporters are involved in the transport of lignin precursors across plasma and vacuolar membranes.
Proc. Natl. Acad. Sci. USA,107(52):22728-22733 (2010).
Bhuiya M.W. and Liu C.-J.
A cost-effective colorimetric assay for phenolic O methyltransferases and characterization of caffeate 3-O-methyltransferases from Populus trichocarpa.
Analytical Biochemistry, 384(1): 151-158 (2009).
Gou J.-Y., Yu X.-H. and Liu C.-J.
A hydroxycinnamoyltransferase responsible for synthesizing suberin aromatics in Arabidopsis.
Proc. Natl. Acad. Sci. USA, 106:18855-18860 (2009).
Yu, X.-H., Gou, J.-Y. and Liu C.-J.
BAHD superfamily of acyl-CoA dependent acyltransferases in Populus and Arabidopsis: Bioinformatics and gene expression.
Plant Mol Biol., 70(4):421-442 (2009).
Baerson S.R., Dayan F.E., Rimando A.M., Dhammika Nanayakkara N.P., Liu C.J., Schroder J., Fishbein M., Pan Z., Kagan I.A., Pratt, L.H.,
Cordonnier-Pratt M.-M. and Duke S.O.
A functional genomics investigation of allelochemical biosynthesis in Sorghum biocolor root hairs.
J. Biol. Chem., 283(6):3231-47 (2008).
Gou J., Park S., Yu X.-H., Miller L.M. and Liu C.-J.
Compositional characterization and imaging of “wall-bound” acylesters of Populus trichocarpa reveal differential accumulation of acyl molecules in normal and reactive woods.
Planta, 229(1):15-24 (2008).
Yu X-H., Chen M.-H. and Liu C.-J.
Nucleocytoplasmic-localized acyltransferases catalyze the malonylation of 7-O-glycosidic (iso)flavones in Medicago truncatula.
Plant Journal, 55(3):382-396 (2008).
Naoumkina M., Farag M.A., Sumner L.W., Tang Y., Liu C.-J. and Dixon, R.A.
Different mechanisms for phytoalexin induction by pathogen and wound signals in Medicago truncatula.
Proc. Natl. Acad. Sci. USA, 104(46):17909-17915 (2007).
Deavours B.E., Liu C.-J., Naoumkina M., Tang Y., Farag M.A., Sumner L.W., Noel J.P. and Dixon R.A.
Functional analysis of members of the isoflavone and isoflavanone O-methyltransferase enzyme
families from the model legume Medicago truncatula.
Plant Mol Biol., 62(4-5):715-733 (2006).
Coiner H., Schröder G., Wehinger E., Liu C.-J., Noel J.P., Schwab W. and Schröder J.
Methylation of sulfhydryl groups: a new function in a family of small molecule plant
Plant J, 46(2):193-205 (2006).
Liu C.-J., Deavours B.E., Richard S.B., Ferrer J.L., Blount J.W., Huhman D., Dixon R.A. and Noel J.P.
Structural basis for dual functionality of isoflavonoid O-methyltransferases in the evolution
of plant defense responses.
Plant Cell, 18(12):3656-3669 (2006).
Liu C.-J. and Noel J.P.
Flavonoids: recent advances in molecular biology, biochemistry, pharmaceutical
applications and metabolic engineering.
In: Plant Genetic Engineering Vol. 7: Metabolic Engineering and Molecular Farming, (Ed. Jaiwal P.K.)
Studium Press, Houston, pp 225-259 (2006).
Yu X.-H. and Liu C.-J.
Development of an analytical method for genome-wide functional identification of plant acyl-coenzyme A-dependent acyltransferases.
Anal Biochem, 358(1):146-148 (2006).
Liu C.-J., Huhman D., Sumner L.W. and Dixon R.A.
Regiospecific hydroxylation of isoflavones by CYP81E enzymes in Medicago truncatula.
Plant J., 36:471-484 (2003).
Liu C.-J., Blount J.W., Steele C.L. and Dixon R.A.
Bottlenecks for the metabolic engineering of isoflavone glycoconjugates in Arabidopsis.
Proc Natl Acad Sci USA, 99:14578-14583 (2002).
Liu C.-J., Heinstein P. and Chen X.Y.
Expression pattern of genes encoding farnesyl diphosphate synthase and sesquiterpene cyclase
in cotton suspension-cultured cells treated with fungal elicitors.
Mol Plant Microbe Interact, 12(12):1095-1104 (1999).