Abstract
Comparative studies conducted on the genetic variat ion of metal-tolerant populations and their non-met altolerant counterparts have been performed on numerous species using isozyme markers. Analysis of genet ic differences among plant populations growing in heavy metal-contaminated and uncontaminated regions are limited. The main objectives of the present study w ere to compare ISSR and microsatellite markers in assessing genetic variation in D. cespitosa populations that colonized metal-contaminated and uncontaminated regions in Northern Ontario, Canada. Total genomic DNA from D. cespitosa samples were amplified with ISSR and SSR primers using optimized PCR conditions. The level of polymorphic loci varies from 46 to 74% for ISSR analysis. The level of observed heterozygosity was moderate to high ranging from 0.44 to 0.68 for the SSR primers used. But no significant difference in genetic variation levels was detected between metal contaminated and uncontaminated sites with SSR markers. There was a significant reduction of polymorphic loci in sample s from highly metal-contaminated areas of the Cobal t region compared to the reference sites based on ISS R analysis. Use of a combination of different marke r systems is recommended to analyse genetic variation in plant populations.
Highlights
Contaminant is a mutagen, genetic variation within the affected population will remain elevated and may Genetic diversity comprises the entire complement of genetic characteristics associated with a population or a species
Genetic variation may be lost as a result of population bottleneck in response to the severe selective pressures acting upon the population and/or the migration of a small subset of individuals into the contaminated areas resulting in a founder effect (Bourret et al, 2007)
The lowest level of polymorphic loci of 46% on the average was observed in samples from the Cobalt region (Cobalt-3, Cobalt-4 and Cobalt-5) which has the highest accumulation of heavy metal (Table 2)
Summary
Contaminant is a mutagen, genetic variation within the affected population will remain elevated and may Genetic diversity comprises the entire complement of genetic characteristics associated with a population or a species. It is crucial for maintaining healthy populations that are able to respond favourably and adapt to changes or disturbances in the environment (Bourret et al, 2007). Previous studies on the genetic diversity of Deschampsia cespitosa, based on allozyme and RAPD (random fragment length polymorphism) analysis, have indicated to some extent the reduced genetic diversity of populations located on contaminated soil (Bush and Barrett, 1993; Nkongolo et al, 2001).
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