Grantee Research Project Results
1999 Progress Report: Ecosystem Monitoring via Genetic Diversity Surveys of Dandelions using VNTR multi-locus DNA probes
EPA Grant Number: R826602Title: Ecosystem Monitoring via Genetic Diversity Surveys of Dandelions using VNTR multi-locus DNA probes
Investigators: Rogstad, Steven , Keane, Brian
Institution: University of Cincinnati
EPA Project Officer: Hahn, Intaek
Project Period: July 14, 1998 through July 13, 2001 (Extended to July 13, 2003)
Project Period Covered by this Report: July 14, 1999 through July 13, 2000
Project Amount: $291,045
RFA: Ecological Indicators (1998) RFA Text | Recipients Lists
Research Category: Aquatic Ecosystems , Ecological Indicators/Assessment/Restoration
Objective:
New methodologies in molecular genetics may provide novel types of ecological indicators for monitoring the integrity of natural ecosystems and the sustainability of ecosystems that are affected by anthropogenic influences. One type of ideal ecological indicator would be an organism that grows in a wide variety of habitats that could easily be used to monitor for the presence of mutagens or anthropogenic factors that alter population genetics. We are investigating dandelions (Taraxacum officinale Weber; Asteraceae) as a potential model, ecological indicator organism because: (1) dandelions have an extremely wide ecological amplitude, growing almost worldwide from sea-level to alpine biomes, and from the tropics to north-temperate habitats; (2) dandelions grow rapidly, and populations can be easily manipulated and monitored; (3) it has been documented that a variety of pollutants can be sequestered in dandelion tissues; (4) dandelion seeds are produced asexually rendering the detection of mutations easy; and (5) we have generated preliminary data using variable-number-tandem-repeat (VNTR) DNA probes (used in DNA fingerprinting) that suggest that mutation rates and population genetic diversity parameters can be analyzed successfully with dandelions. The specific hypothesis to be tested is: dandelions can be used as a sensitive ecological indicator species through comparative analyses of VNTR genetic markers since differences in: (1) mutation rates, and/or (2) population genetic structure, can be detected between pollution impacted versus non-impacted populations.Progress Summary:
Twenty-nine study sites in the Midwestern United States were selected to span a range of pollution exposure as determined by analyses of PM10 (equals the amount of airborne particulate matter < 10 micrometers; see www.epa.gov/airsweb/), or as determined by a known history of intense exposure (four sites). Soils and dandelion tissues from these sites have been analyzed for eight metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn). A positive, statistically significant correlation exists between the mean annual PM10 recorded for sites and each metal. However, only three of the metals (Mn, Pb, and Zn) exhibited positive, statistically significant correlations between soil and fall leaf concentrations. Further, sampling dandelion tissues at eight of the sites in both spring versus fall revealed that leaf tissue metal concentrations increased for five of the metals over the growing season. These results indicate that the amount of a metal at a site does not always predict the amount sequestered in the dandelion tissues, other factors such as site seasonal climate history, substrate characteristics, and/or dandelion genotypes present at a site possibly interacting with uptake. However, we have now analyzed the transmission of well over 40,000 VNTR genetic markers in over 100 parent to clonal offspring arrays from 11 sites (average mutation rate = 0.0089, or 1 mutant transmission per 113 markers transmitted), and have found a positive, statistically significant relationship between the concentration of five of the metals (Cd, Cr, Fe, Mn, and Ni) in the leaf tissue and the mutation rate. Analysis of VNTR marker variation in populations (three large transects, and sampling at two polluted versus two relatively pristine sites) indicates that some dandelion clones are distributed very widely, although clones with narrow distributions (e.g., restricted to a site) have also been found.
The above is a preliminary description of our major results to date (at least four more sites will be similarly examined during the remaining year). If the above trends hold, we will conclude the following: (1) PM10 is a good indicator of the degree of soil contamination for the metals examined; (2) dandelions are not effective biomonitors in the sense that their tissues sequester metals in proportion to the concentration of metals in the soil; and (3) dandelions may be good ecosystem biomonitors in the sense that they reflect metal bioavailability, that is, how the plant population at a site is interacting with the metals to sequester them. Further, dandelions thus far appear to be good mutation stressor biomonitors, indicating that as the tissue exposure to metals, or possibly other mutagen stressors, increases, mutation rates at a site increase.
By the end of this project, we expect to determine whether VNTR markers in dandelions can be used as sensitive indicators of anthropogenic changes in population genetic diversity due to either altered mutation rates or stressor induced selection. If mutation rates or genetic diversity vary in correlation with increasing pollution, dandelions provide an easily utilized biomonitor to survey the ecological integrity and sustainability of a wide range of habitats across multiple spatial scales throughout the world.
Future Activities:
Besides completing the above projects, we intend to grow dandelions in controlled media spiked with mixtures of metals reflecting the range found in this study to investigate whether mutation rates increase with increasing metal concentrations. Further, we have initiated experiments to determine whether dandelions from the worst polluted sites have higher fitness when competing with dandelions from more pristine sites when both are grown in polluted and non-polluted soils.Journal Articles on this Report : 3 Displayed | Download in RIS Format
| Other project views: | All 27 publications | 15 publications in selected types | All 13 journal articles |
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Keane B, Pelikan S, Toth GP, Smith MK, Rogstad SH. Genetic diversity of Typha latifolia (Typhaceae) and the impact of pollutants examined with tandem-repetitive DNA probes. American Journal of Botany 1999;86(9):1226-1238. |
R826602 (1998) R826602 (1999) R826602 (2000) R826602 (2001) R826602 (Final) |
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Lim HW, Pelikan S, Rogstad SH. Genetic diversity among populations and size classes of buckeyes (Aesculus: Hippocastanaceae) examined with multilocus VNTR probes. Plant Systematics and Evolution 2002;230(3-4):125-141. |
R826602 (1998) R826602 (1999) R826602 (2000) R826602 (2001) R826602 (Final) |
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Rogstad SH, Keane B, Beresh J. Genetic variation across VNTR loci in central North American Taraxacum surveyed at different spatial scales. Plant Ecology 2002;161(1):111-121. |
R826602 (1999) R826602 (2000) R826602 (2001) R826602 (Final) |
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Supplemental Keywords:
air, soil, risk assessment, ecological effects, genetic polymorphisms, population responses, bioavailability, sensitive populations, mutagens, cumulative effects, particulates, integrated assessment, conservation, phytoremediation, bioremediation, environmental chemistry, monitoring, ecology, genetics, measurement methods, Midwest, CO, IN, KY, OH, PA, Colorado, Indiana, Kentucky, Ohio, Pennsylvania, midwest., RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Ecology, Ecosystem/Assessment/Indicators, Ecosystem Protection, exploratory research environmental biology, Ecological Effects - Environmental Exposure & Risk, Environmental Monitoring, Ecology and Ecosystems, Ecological Risk Assessment, Ecological Indicators, ecological exposure, risk assessment, anthropogenic stresses, dandelions, molecular genetics, genetic polymorphism, multiple spatial scales, survey, ecosystem indicators, assessment methods, DNA, genetic diversityRelevant Websites:
http://www.biology.uc.edu/faculty/rog/steve.htm
http://www.enn.com/enn-news-archive/1999/10/102899/cattail_6793.asp
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.