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item Slotta, Tracey
item Horvath, David
item Foley, Michael

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/6/2006
Publication Date: 11/1/2006
Citation: Bodo Slotta, T.A., Rothhouse, J.M., Horvath, D.P. Foley, M.E. 2006. Genetic diversity of Canada thistle (Cirsium arvense)in North Dakota. Weed Science. 54:1080-1085.

Interpretive Summary: Canada thistle is a highly invasive introduced weed that is found throughout North America in a wide variety of locations. It is especially problematic in agriculture and recreation areas, since no herbicide or biological control safely destroys populations. In this project, the amount of genetic variation in Canada thistle populations was surveyed for North Dakota. The level of genetic variation can be an indication of how the plants are spreading and how they may adapt to future control efforts. Our results show that seeds, not roots, are the dominant mechanism for the continued spread of Canada thistle. Furthermore, pollen and seed movement between populations is contributing to the genetic diversity and continued success of Canada thistle in North America.

Technical Abstract: Canada thistle, Cirsium arvense, is a noxious weed that occurs in a wide range of habitats and is difficult to control due to its extensive root system and prolific seed production. Here, we focused on estimating the level of genetic diversity between populations in North Dakota as a first step in examining diversity across North America. Two types of genetic markers, inter-simple sequence repeats (ISSRs) and microsatellites were used. Both markers types resulted in polymorphic alleles suitable for assessing diversity. Analysis of molecular variance (AMOVA), molecular diversity analyses and cluster analysis were conducted. Highly significant variation was detected between populations (P<0.01). The greatest variance recovered was between individuals within populations. Gene flow among populations in the Northern Great Plains was indicated by the presence of shared alleles between the ND and MN populations and in cluster formation. Multiple introductions and continued gene flow between populations has led to the continued success of Canada thistle as an invasive plant in North America.