DNA-Based Marker Systems to Determine Genetic Diversity of Weedy Species and Their Application to Biocontrol

Abstract

DNA-based molecular markers may provide information about introduced weedy species that would be useful in biological weed control efforts. Chloroplast DNA restriction fragment length polymorphisms (cpDNA RFLP) and random amplified polymorphic DNA (RAPD) analysis are two DNA-based marker techniques that can provide estimates of genetic variation in native and introduced populations of weedy species. Profiles provided by these techniques could furnish the necessary information to determine the geographic origins of introduced species and provide evidence for multiple introductions. Although DNA-based markers would not necessarily identify the genetic basis for host-pest compatibility, they would enable identification of specific host genotypes. Current criteria for selecting a weedy species as a target for biological control are primarily political and economic. The importance of genetic diversity and population structure in determining the vulnerability of plant populations to insects or diseases has not been fully appreciated. Estimates of genetic diversity based on DNA marker analysis could be used as one criteria for determining which plants are targeted for biological control. The success of biological weed control efforts has been limited by the high levels of genetic diversity occurring in target weed specks and the lack of biocontrol agent and target weed compatibilities. DNA-based markers may be used to increase our understanding of these factors and contribute to the success of biological weed control by helping to target the most vulnerable species and provide more realistic expectations of the potential for success given available resources.

Genetic Variation and Molecular Biogeography of a North American Invasive Plant Species (Alliaria petiolata, Brassicaceae)

“…Knowledge of the genetic variability within invasive species can be used to determine the geographic origins of introduced plants and can be used as well to determine whether the populations are the result of single or multiple introductions. This information can then be used to select potential biocontrol agents and to determine which plants will be the most vulnerable to biocontrols (Nissen et al 1995). If populations of an invasive species are highly divergent, indicating that there were multiple introductions from different sources, control attempts using natural enemies from one source population may prove futile (Sun 1997).…”

Chloroplast and microsatellite DNA diversities reveal the introduction history of Brazilian peppertree (Schinus terebinthifolius) in Florida

“…If an invasive species is an intra‐ or interspecific hybrid however, it will no longer have closely co‐adapted natural enemies and so may require more extensive testing with biocontrol agents sampled from the different source regions. Application of molecular techniques for genetically characterizing target weed populations and biological control agents provides opportunities for more precise ‘biotype matching’ and for ascertaining the introduction history of the invasive species (Nissen et al . 1995).…”

Molecular and morphological evidence reveals introgression in swarms of the invasive taxa Fallopia japonica, F. sachalinensis, and F. ×bohemica (Polygonaceae) in the United States

“…With the heightened interest in biological control for these species in the U.S. (Shaw and Sieger, 2002), knowledge of the role of inter-and intraspecific sexual reproduction and hybridization may be critical, and the effectiveness of such control efforts may depend upon genotype-specific interactions (Nissen et al, 1995).…”