ROLE OF FERULIC ACID BRIDGES BETWEEN LIGN IN AND POLYSACCHARIDES IN THE GROWTH OF WHEAT (TRITICUM-AESTIVUM) INTERNODES

The internodes and leaf sheath walls of isogenic and near-isogenic lin es of wheat (Triticum aestivum L. em Thell) with varying dosages of dw arfing genes have been analyzed for lignin contents and monosaccharide and hydroxycinnamic acid compositions. Both lignin and glucose conten ts of the first four internodes from the top showed a clear positive c orrelation with the length of the first internode (topmost, used as an index of dwarfism), but the ratio of syringyl nuclei to guaiacyl nucl ei (S/V ratio) of lignin, determined by alkaline nitrobenzene oxidatio n, and xylose contents were independent of the first internode length. When compared with lines carrying dwarfing genes, wall components of normal (taller) wheat plants were characterised by a greater content o f etherified ferulic acids which also are esterified to form bridges b etween lignin and polysaccharides, and a smaller content of ferulic ac id linked only by esterification. It is suggested that matrix componen ts of the wall are reinforced with bridging by ferulic acid etherified to lignin and to polysaccharides and that they are quantitatively mor e numerous in normal (taller) lines.