Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/7/2005
Publication Date: 6/8/2005
Citation: Slotta, T.A., Foley, M.E., Horvath, D.P. 2005. Homology of microsatellite and ISSR markers in Cirsium (Asteraceae). [Abstract]. Society of Systematic Biologists Meeting. Interpretive Summary: Canada (Cirsium arvense) and Bull (C. vulgare) thistle are European native species that invade rangeland, agriculture and natural areas throughout North America. Canada thistle is classified as a noxious weed in 41 states and can cause severe land use and economic losses. Previous efforts to find biological control agents (insects or fungi) had limited success. For example, insects released to feed on Canada or Bull thistle attacked several thistle species native to North America, one of which is considered endangered. The current study is looking at genetic markers to determine how closely related the introduced, weedy thistles are to the native species. Several genetic markers have been developed for Canada thistle and were tested for variation in the other thistle species. Most of these genetic markers successfully worked for the native species. There was limited overlap in the comparison of DNA sequences in the native European (Canada and Bull) and native North American (Swamp, Flodman’s and Wavy-leaf) thistles. Less genetic diversity was detected in the North American thistles than in the European species. Results of this project will be an asset in the search and development of more effective control measures for Canada thistle.
Technical Abstract: Canada (Cirsium arvense) and Bull (C. vulgare) thistle are Eurasian species that invade rangeland, agriculture, and natural areas throughout North America. Canada thistle is classified as a noxious weed in 41 states and can cause severe habitat and economic losses. To assess the level of genetic diversity within and gene flow between Cirsium arvense and relatives in the Northern Great Plains, microsatellite markers were designed and compared to ISSRs (inter-simple sequence repeats). A set of 17 ISSR markers were screened, seven of which consistently amplified polymorphic loci in C. arvense populations across North America and indicate 24.4% genetic variation, on average. Among Cirsium species sampled, C. vulgare had the greatest homology to C. arvense ISSR loci. From 31 microsatellite loci identified in C. arvense, four consistently amplified polymorphic alleles in C. arvense and indicate 22.4% genetic variation, on average. These four microsatellites were also surveyed in congeners of C. arvense. As with the ISSR markers, C. vulgare had the greatest homology among loci. The level of diversity detected in C. arvense populations in North Dakota (HT=24.92) was less than that previously reported for Europe (HT=71.5). Alleles homologous within Cirsium were sequenced and surveyed for utility as phylogenetic tools. Several regions were conserved between Eurasian and North American thistles. Sequences were also obtained for the ITS and ETS regions and maximum parsimony and neighbor joining analyses conducted. The relationships inferred from the various genetic markers were compared. Greater resolution was obtained using the ISSR and microsatellite markers.