Cell Wall Degradability of Transgenic Tobacco Stems in Relation to Their Chemical Extraction and Lignin Quality

The down regulation of cinnamyl alcohol dehydrogenase (CAD) activity in tobacco stems resulted in improved degradability without changes in cell wall composition. In this study, some changes were evidenced in cell wall solubilization by NaOH, cellulase, and DMSO treatments. Transgenic plants had an altered cell wall structure, the components of which were more accessible to alkali extraction. In plants at the same stage of maturity, cell wall degradability was linked to the yield of acid-precipitated fraction of the NaOH-soluble extract. Aldehydes that should have been incorporated in the cell wall were possibly detected in the different extracts. Guaiacyl and syringyl monomers were distributed differently in the controls and the antisense saponified residues and acid-precipitated fractions. It is suggested that polymeric lignin structure differs. These findings may help in the understanding of the improvement of cell wall digestibility.