Use of microsatellite markers in management of conifer forest species

Abstract

Within the past ten years a new class of genetic marker¹ has risen to prominence as the tool of choice for many geneticists. Microsatellite DNAs, or simple sequence repeats (SSRs), were first characterized as highly informative genetic markers in humans (Weber and May, 1990; Litt and Luty, 1990), and have since been found in practically all organisms. SSRs are short stretches of repeated DNA sequence, where the repeats are composed of a particular 2 to 5 DNA nucleotide motif, and are organized in tandem arrays of 4 to >40 repeat units. Compared to other types of DNA sequence variation, such as single nucleotide substitutions, SSRs tend to be more mutable. The mutations are generally manifested as gain or loss of individual repeat units, referred to as step-wise mutations, thus giving rise to a series of alleles that have discrete size differences (Figure 1). Within most species' genomes, that is, within their complement of chromosomal DNA, SSRs are abundant, widely distributed, and frequently surrounded by non-repetitive, unique DNA sequences. It is this latter property that allows use of the PCR (polymersse chain reaction) technique to amplify a specific single SSR locus from a small, sample of DNA. Following PCR amplification, alleles of the locus can be scored as phenotypically codominant bands on a gel. By use of PCR methodology many informative SSR loci can be genotyped very quickly from small amounts of tissue, and for comparatively reasonable costs.

Citation

Echt, Craig S. 1999. Use of microsatellite markers in management of conifer forest species. In: Strategies for improvement of forest trees. Council for Forest Reasearch and Development: 75-82. (1999)