Molecular Analysis of Red Oak (Quercus rubra) Populations from a Metal Contaminated Region in Northern Ontario (Canada).

Metal toxicity is a major cause of abiotic stress in plants. Several taxa have developed overtime different coping mechanisms to soil metal contamination to maintain physiological concentrations of essential plant nutrients and to avoid toxicity. The main objective of the present study was to characterize red oak (Quercus rubra) populations from a metal-contaminated region in Northern Ontario. Overall, 10 populations that include seven contaminated and three reference sites were targeted. There were significant differences in soil metal content between metal contaminated and uncontaminated sites for the main elements (nickel, copper and zinc). Small differences between these two groups of sites were also observed for cation exchange capacity (CEC). But no significant differences were found for global DNA methylation among the 10 targeted sites. Genetic variation was determined using Random Amplified Polymorphic DNA (RAPD) markers. The level of polymorphic loci ranged from 61 % to 72 %. The mean values of observed number of alleles (Na), Expected number of alleles (Ne), Neis gene diversity (h) and Shannons information index (I) were 1.69, 1.30, 0.19 and 0.29, respectively. The level of population differentiation (GST) was low (0.17) and the estimated gene flow (Nm) was high (2.39). The total gene diversity (HT) and the mean gene diversity between populations (HS) were 0.22 and 0.19, respectively. Eleven candidate genes that have been known to be involved in nickel and copper tolerance in other plant species have been selected. Regulation of these genes in red oak (Quercus rubra) populations from Northern Ontario is being investigated using qRT-PCR.