THE MECHANICAL-PROPERTIES OF XYLEM TISSUE FROM TOBACCO PLANTS (NICOTIANA-TABACUM SAMSUN)

Tobacco plants (Nicotiana tabacum 'Samsun') have been grown with an an tisense CAD (cinnamyl alcohol dehydrogenase) gene. This modifies ligni n production, resulting in lignin with a greater aldehyde content whic h is easier to extract chemically. This lignin probably has a reduced crosslink density. The changed properties of the lignin affect the lon gitudinal tensile modulus of the xylem tissue (wood), reducing it by o ne third, from 2.8 GPa to 1.9 Gpa. Tobacco xylem tissue cell walls are more sensitive to changes in the properties of the matrix than can be predicted using current cell wall mechanical models. (C) 1998 Annals of Botany Company.