D. R. Dimmel, J. MacKay, E. M. Althen
Feb 28, 2001
Journal of Wood Chemistry and Technology
Mutant loblolly pine trees that are deficient in the enzyme cinnamyl alcohol dehydrogenase (CAD) have been obtained through directed breeding. The lignin in the wood of CAD-deficient trees has a different pool of precursors, resulting in high levels of pulping-resistant C-5 linkages. Wood from a 12-year-old CAD-deficient tree has been pulped under soda and kraft conditions in microdigestors. In comparison to a normal 12-year-old loblolly pine, the CAD-deficient wood was much more easily delignified. In addition, the pulp from CAD-deficient wood was as easy to bleach as a control pulp. The high reactivity of CAD-deficient wood may be related to the lignin size and phenolic content. The molecular weight of an isolated milled wood lignin from CAD-deficient pine was ∼35% less than that from a normal pine tree.