Distinct deposition of ester-linked ferulic and -coumaric acids to the cell wall of developing sorghum internodes.

Sorghum is important as a cereal crop, and also as livestock feed and a renewable energy crop because it produces a large amount of biomass. In grass plants like sorghum, hydroxycinnamates such as ferulic acids (FA) and -coumaric acids (CA) are characteristically ester-linked to the cell wall, and are believed to affect cell wall digestibility. Genetic manipulation of the esterification of FA and CA to the cell wall appears to be one of the solutions to increase the digestibility of the cell wall so as to utilize sorghum biomass effectively. In this study, we measured esterified FA and CA in each stage of internode elongation and determined the accumulation pattern of each hydroxycinnamate. The results revealed that FA were mainly accumulated during the cell elongation stage, and that CA accumulation was increased after the cell elongation stage. Furthermore, 6 of the 12 sorghum BAHD acyltransferase genes were significantly expressed in the elongating internodes, suggesting that these genes might be involved in the feruloylation and/or -coumaroylation of the cell wall in sorghum internodes.