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 i n tobacco stems resulted in improved degradability without changes in cell wall composition. In this study, some changes were evidenced in c ell wall solubilization by NaOH, cellulase, and DMSO treatments. Trans genic plants had an altered cell wall structure, the components of whi ch were more accessible to alkali extraction In plants at the same sta ge of maturity, cell wall degradability was linked to the yield of aci d-precipitated fraction of the NaOH-soluble extract. Aldehydes that sh ould have been incorporated in the cell wall were possibly detected in the different extracts. Guaiacyl and syringyl monomers were distribut ed differently in the controls and the antisense saponified residues a nd 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.