Abstract
Internodes of the maize cell line W401 and bm 1 and bm 3 mutants expressed in W401 were harvested 5 days after anthesis (A5) and at silage (S) stage. The normal maize had a higher total phenolic (TP) content (80.5-90.5 g kg -1 cell wall DM) than both bm 1 and bm 3 mutants (74.4-86.4 and 66.0-84.2 g kg -1 cell wall DM, respectively). TP were inversely related to cellulase digestibility with values of 85.4-91.5, 89.3-92. and 91.3-94.1% for normal, bm 1 and bm 3 . Marked differences in p-coumaric acid concentrations were found ranging from 20.9 to 26.3 g kg -1 cell wall DM for normal, 14.9 to 15.3 g kg -1 for bm 1 to 10.1 to 14.4 g kg -1 for bm 3 . The ferulate pattern was entirely different with the bm 1 genotype providing the lowest tota1 (9.1-10.7 g kg -1 ) and etherified (1.9-2.3 g kg -1 ) values. Although the bm 3 contained more total ferulate (11.5-13.1 vs 10.9-11.7 g kg -1 ), the normal variety had a significantly greater amount of etherified ferulate (2.8-3.4 vs 3.2-4.1 g kg -1 ) implying a greater extent of cross-linking between wall polymers. Recovery of guaiacyl and syringyl residues was greatest in the normal maize with the bm 1 occupying the middle position between the two extremes. Calculated S: G ratios from 4 M NaOH digestion and NMR were in good agreement with the normal line giving the highest ratio, bm 1 intermediate and bm 3 the lowest. Colorimetric analysis revealed a large increase in the aldehyde content of the in situ bm 1 lignin compared to normal and bm 3 genotypes although NMR failed to reveal significant numbers of aldehydic resonances.
Published Version
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