ARS | Publication request: Lignin Acylation in Grasses

Submitted to: Plant Biology Annual Meeting
Publication Type: Abstract
Publication Acceptance Date: March 30, 2007
Publication Date: July 8, 2007
Citation: Marita, J.M., Hatfield, R.D., Frost, K.E. 2007. Lignin acylation in grasses [abstract]. In: Program and Abstract Book of the Plant Biology and Botany 2007 Joint Congress, July 8-11, 2007, Chicago, Illinois. p. 106.

Technical Abstract: Acylation of lignin during growth and development is a commonly found among some plant species. Grasses form unique acylated lignins involving p-coumarate (pCA). In corn rind tissue, it is exclusively attached to the gamma-carbon of lignin monomers, with a strong preference (over 90%) for attachment to sinapyl alcohol residues, indicating an enzymatic process. The p-coumaroyl transferase (pCAT) in corn, which uses an activated form of pCA, was targeted in order to understand the physiological and biochemical roles of lignin p-coumaroylation. The pCAT was purified, and substrates including donor and acceptor molecules were examined. Conjugate formation and detection indicated a higher affinity for specific substrates tested. Corn plants were harvested at the tassel emergence stage of development to examine the temporal and spatial relationships of pCA and pCAT activity with respect to lignification within developing corn stem tissue. Accumulation of pCA and pCAT activity paralleled lignin deposition in cell walls of corn stem. Maximum pCAT activity was found in the middle region of the corn stem (internodes 10-12). The transferase maintained significant levels of activity in the most mature internodes, and detectable levels indicated initiation even in immature tissues. Warm season grasses (C4) and cool season grasses (C3) did not form two distinct classes with respect to their degree of acylation and pCAT activity as expected. This variation in C3 and C4 grasses suggests an independent relationship between cell wall p-coumaroylation and enzyme activity. Corn stems had the most pCA per kg of cell wall, but sorghum had higher pCAT activity. A more in-depth understanding of the pCAT enzyme activity and gene expression in grasses requires further investigation.