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Winner of a 2009 Outstanding Academic Title (OAT) award
Trees continue to maintain a unique significance in the social, ecological and economic systems of the world - as large, long-lived perennials covering 30% of land on Earth; their very nature dictates their importance. An understanding of forest genetics is essential for providing insight into the evolution, conservation, management and sustainability of both natural and managed forests.
Providing a comprehensive introduction to the principles of genetics as important to forest trees, this text integrates the varied sub-disciplines of genetics and their applications in gene conservation, tree improvement and biotechnology. Topics discussed include genetic variation in natural forest trees, the application of genetics in tree improvement and breeding programs, and genomic sciences and molecular technologies.
10-60 base pairs is repeated many times and is dispersed throughout the genome. Minisatellites of variable lengths, called variable number tandem repeats (VNTRs), were first discovered in humans and have been used for DNA fingerprinting (Jeffreys et al., 1985a,b). Polymorphic minisatellite sequences have been detected in both angiosperm and gymnosperm tree species (Rogstade/a/., 1988, 1991;KvarnhedenandEngstrom, 1992). Fig. 2.7. Fluorescent in situ hybridization (FISH) in Picea glauca (2N = 24).
genotypes (DD, Dd and dd) are found in the 1:2:1 ratio, respectively. However, only two phenotypes are found, tall and dwarf, in the ratio of 3:1, respectively. Finally, Mendel proposed that the 3:1 ratio observed in the progeny of selfed FI plants is expected if the D and d alleles are transmitted from each parent to the offspring at random (Law 3, Table 3.1). The frequencies of the offspring genotypes are the products of the frequencies of the alleles transmitted from each parent. The frequency
inherited strictly from the paternal parent. Box 3.4. Estimation of genetic linkage between two allozyme loci in Pinus rigida. Genetic linkage in forest trees can be illustrated using an example from an allozyme study by Guries et al. (1978). Allozymes are codominant genetic markers (Chapter 4) and the two alleles at a heterozygous locus are often designated as fast (F) and slow (S), based on their mobility difference on gels following electrophoresis. Guries et al. (1978) assayed a number of
amplification products were assayed by denaturing gradient gel electrophoresis (DGGE). 74 Genetic Markers structural gene loci whereas the others generally reveal variation in non-coding regions of the genome. Such structural gene markers are called genie markers versus non-genie markers. This distinction can be important for some applications of genetic marker analysis, such as candidate gene mapping and the discovery of single nucleotide polymorphisms (SNPs) within candidate genes. SNPs are
each genotype by the total number of individuals sampled (e.g. the frequency of Gdh-ll, written f(Gdh-ll), is 21/64 = 0.328). To calculate allele frequencies, remember that each genotype of a diploid tree carries two alleles. Therefore, the total number of alleles is twice the number of individuals sampled, and allele frequency is the proportion of all alleles that are of the specified type. In this example, the frequency of allele Gdh-l, written f(Gdh-l), is [2(21) + 36]/[2(64)] = 0.609, and