Brown midrib mutant maize with reduced levels of phenolic acids ether-linked to the cell walls

Abstract

Cell wall composition and rumen degradability of leaf blade, leaf sheath and stem of normal and brown midrib mutant 3 (bmr3) maize ( Zea mays L.) phenotypes were determined in this study. Concentrations of ether-linked phenolic acids were determined by acid and alkaline hydrolysis of whole cell wall materials. The bmr3 maize had higher rumen degradability and lower contents of cellulose, lignin, ferulic and p-coumaric acids esterified and/or etherified to the cell walls, and a lower ratio of xylose to arabinose residues as compared with the normal phenotype. Cellulose degradability was inversely correlated with the acetyl bromide lignin, but not with the acid detergent lignin or Klason lignin. The contents of ether-linked ferulic and p-coumaric acids, whether determined by acid or by alkaline hydrolysis, were inversely correlated with degradability. The bmr3 mutation is characterized not only by a lower lignin content, but also by a reduced level of total ether-linked ferulic acid which is thought to play an important role in cross-linking lignin and cell wall polysaccharides.