The use of electrophoretic markers in seed orchard research

Abstract

Gene flow is a critical determinant of population genetic structure, playing an important role in forest tree improvement, conservation genetics, and the potential for the escape of engineered genes. A review of gene flow among plant populations yields the following generalization: although gene flow varies substantially among species, populations, seasons, and even individual plants, at physical isolation distances of hundreds to thousands of meters, gene flow levels are frequently sufficient to counteract genetic drift and moderate levels of directional selection. Gene flow will be hard to predict a priori. Therefore, any project or management plan depending on a given level of gene flow or reproductive isolation should include a genetically-based method to measure the actual gene flow among the populations involved.Abstract.Biochemical markers are ideally suited for addressing questions concerning genetic or parental identity. For production seed orchards, such questions are common as a consequence of the uncertainty of paternity in non-controlled cross situations. During the last decade, electrophoretic procedures have been used extensively to investigate issues such as:-clonal identification, -pollen contamination levels, -mating systems, -supplemental mass pollination (SMP) verification, -patterns of gene flow, and -levels of pollen competition.A number of patterns have emerged from this work. Most notable, contamination rates are disturbingly high, clonal phenology and pollen application methodology influence SMP success, and phenology and proximity are important in determining paternal success. Results are discussed with reference to orchard management prescriptions.This paper was distibuted within Weyerhaeuser Company as an internal research report.

DNA Profiling, Pedigree Lineage Analysis and Monitoring in the Australian Breeding Program of Radiata Pine

“…The first checkpoint would be the correctness of the ramets of clones in breeding arboreta on which crosses are going to be made for progeny trials from which new selections will eventually be made. On average about 10 % of ramets were found to have the incorrect genotype in species such as Douglas-fir, Scots pine and loblolly pine (ADAMS, 1983;HARJU and MUONA, 1989;WHEELER and JECH, 1992). The average figure in this study of 2.6 % is therefore low, especially when it is considered that overall PI values with the microsatellites are so low that all errors should be detected unequivocally, unlike perhaps with isozyme markers used in earlier studies.…”

Pollen contamination in a maritime pine polycross seed orchard and certification of improved seeds using chloroplast microsatellites

“…Several studies using genetic markers have demonstrated that a large proportion of a young orchard's seed crop is fertilized by unselected contaminant sources (Stoehr et al 1998;Harju and Nikkanen 1996;Paule et al 1993;Wheeler and Jech 1992;Yazdani and Lindgren 1991). It is also the case in mature seed orchards (reviewed by Adams et al 1997).…”

Complex patterns of mating revealed in a Eucalyptus regnans seed orchard using allozyme markers and the neighbourhood model

“…Understanding levels of pollen gene flow is important for evolutionary and conservation biologists (Neigel 1997; Sork et al . 1999), but also for the practical management of gene pools in commercial agriculture crops and forest populations (Wheeler & Jech 1992; Orson & Oldfield 1999; Adams & Burczyk 2000), especially as more transgenic species are introduced (Rogers & Parkes 1995). Direct estimation methods using genetic markers and paternity exclusion are considered reliable tools for assessing contemporary pollen gene flow (Bossart & Prowell 1998; Sork et al .…”