Understanding How Plants Make Cell Wall Lignin

Growth phenotype of ref8 tt4-2 double mutant, which lacks flavonoids, is indistinguishable from that of ref8.

The Science

Plant development is regulated by many complex processes involving both environmental and genetic factors. One of these processes, the phenylpropanoid pathway, is responsible for biosynthesis of the cell wall structural component lignin as well as flavonoids, a diverse set of compounds involved in plant pigmentation and defense. Lignin protects polysaccharides in the plant cell wall from degradation. However, this natural protection also impedes our ability to breakdown biomass for biofuel production. Plants with lower lignin content are smaller overall, i.e., have decreased biomass production, but it has not been clear whether this decrease in plant fitness is due to lignin deficiency or flavonoid accumulation. Researchers at Purdue University studying the model plant Arabidopsis thaliana present evidence linking growth reduction in mutant varieties of Arabidopsis to lignin deficiency. Researchers show that expression of a newly characterized gene bypassing HCT and C3′H partially restores both lignin biosynthesis and growth in HCT-RNAi plants, demonstrating that a biochemical pathway downstream of coniferaldehyde, probably lignification, is essential for normal plant growth.These studies of the phenylpropanoid pathway help define its impacts on biomass production, information of great importance in seeking improved biofuel feedstocks.

Principal Investigator

Clint Chapple
Purdue University

BER Program Manager

Pablo Rabinowicz

U.S. Department of Energy, Biological and Environmental Research (SC-33)
Biological Systems Science Division
[email protected]


Li, X., Bonawitz ND, Weng J-K, and Chapple C. 2010. “The Growth Reduction Associated with Repressed Lignin Biosynthesis in Arabidopsis thaliana is Independent of Flavonoids,” Plant Cell 22(5), 1620–32. DOI:10.1105/tpc.110.074161.