BROWN MIDRIB MUTANT MAIZE WITH REDUCED LEVELS OF PHENOLIC-ACIDS ETHER-LINKED TO THE CELL-WALLS

Cell wall composition and rumen degradability of leaf blade, leaf shea th 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 degrada bility and lower contents of cellulose, lignin, ferulic and p-coumaric acids esterified and/or etherified to the cell walls, and a lower rat io of xylose to arabinose residues as compared with the normal phenoty pe. Cellulose degradability was inversely correlated with the acetyl b romide lignin, but not with the acid detergent lignin or Klason lignin . The contents of ether-linked ferulic and p-coumaric acids, whether d etermined 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-linke d ferulic acid which is thought to play an important role in cross-lin king lignin and cell wall polysaccharides.