Genomic Approaches to Manipulating Lignin Composition and Amount in Wood, 1996 Pulping Conference Proceedings

O’Malley, David M., MacKay, J. Whetten, R., Campbell, M.,Liu, B.-H., Sederoff, R.R. - North Carolina State University

The effectiveness of tree improvement through selective breeding could be enhanced by advances in genomic science. Genomic science has revolutionized genetic approaches to understanding human physiology and disease. In contrast with the traditional genetic approaches for plants that are based on controlled breeding, genetic studies of humans are population-based, and rely on naturally occurring DNA sequence variation. Segregating molecular markers in families, pedigrees, and populations can be used to define genetic components of phenotypic variation. Ultimately, these genetic effects can be precisely located in small regions of the genome, and associated with specific genes. For forest trees, knowledge of physiology and biochemistry of wood can be integrated with these approaches to identify genetic variants that could be useful for manipulating chemical composition and properties through breeding. One example is the discovery of a nonexpressed allele of the gene coding for cinnamyl alcohol dehydrogenase in loblolly pine. Homozygotes for this allele have properties similar to those obtained through genetic engineering. Plants generated through genetic engineering must be extensively tested, a laborious and time-consuming effort in trees. Genetically engineered trees also face regulatory restraints to deployment. In contrast to genetic engineering approaches, the effects of naturally occuring variants on industrial wood properties, viability, and growth are more readily evaluated using existing plant material for retrospective studies. Furthermore, these genetic variants could be used immediately in conventional breeding programs. The level of genetic variability in populations of forest trees is high, and the potential of this approach as an alternative to genetic engineering of trees should be explored.