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United States Department of Agriculture

Agricultural Research Service

Research Project: Acquisition, Evaluation and Conversation of Temperate Forage Legume Genetic Resources

Location: Plant Germplasm Introduction and Testing

Title: Using molecular markers to guide the in situ conservation of Trifolium thompsonii: a vulnerable endemic of Washington

Authors
item Greene, Stephanie
item Kisha, Theodore

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 1, 2009
Publication Date: November 3, 2009
Citation: Greene, S.L., Kisha, T.J. 2009. Using molecular markers to guide the in situ conservation of Trifolium thompsonii: a vulnerable endemic of Washington. Agronomy Abstracts. American Society of Agronomy, Madison, WI. 2009-53127.

Interpretive Summary: Thomson clover (Trifolium thompsonii) is an attractive endemic found within a 150 km sq area on the east sides of the Cascade Mountains, bordering the Columbia River. Only 9-14 populations have been documented, and only two sites are protected. The objective of this study was to assess the genetic structure within and between populations to determine if existing strategies to protect this species are sufficient. DNA molecular marker analysis was carried out on 50 plants from 4 populations sampled in 1995 and 2004. We found that the populations at the four sites were genetically distinct. Over fifteen years, the population genetic structure had changed, but not substantially. Based on the analysis, we believe that existing in situ reserves are sufficient to protect the species, but that further work needs to be carried out to confirm this.

Technical Abstract: Thomson clover (Trifolium thompsonii) is a narrow, endemic legume species found on the east side of the Cascade Mountains. Only 9-14 populations have been documented, and only two sites are protected. The objectives of this study were to gain a preliminary understanding of the genetic structure of representative Thompson clover populations by estimating genetic diversity, differentiation and gene flow. We also wanted to examine if population genetic structure had changed over the course of 15 years. AFLP analysis was carried out on 50 plants from 4 populations sampled in 1995 and 2004. The preliminary analysis was based on 2 primer pairs and 45 scored bands. We found that average percent polymorphic loci was 91.88% and no fragments were unique to any population. Genetic variation was generally higher in BADGER and RNA then TENAS and KEYSTONE, although the small number of loci used may result in statistical bias. AMOVA indicated that individual plant variation within sites explained 92% of the total variation, variation among sites explained 6 % of the variation, and sampling year explained only 2% of the total variation. An admixture was evident among populations, yet each population was differentiated. A likely explanation is that Thompson clover has historically been contiguously distributed across the area, but now remains as fragmented populations that may have little or no gene flow. Based on this preliminary analysis, the in situ reserves (RNA and KEYSTONE) appear to conserve species diversity. However, it’s important to carry out further research that uses more markers and examines the presence of unique rare alleles before we can adequately identify the Relevant Genetic Unit for conservation.

Last Modified: 9/10/2014
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