Molecular analysis of red maple (Acer rubrum) populations from a reclaimed mining region in Northern Ontario (Canada): soil metal accumulation and translocation in plants

Abstract

Red maple (Acer rubrum) species is one of the most widespread deciduous (hardwood) trees of eastern North America. It is among the dominant tree species in the Northern Ontario after land reclamation. To date, the effects of heavy metal contamination from the mining activities on terrestrial ecosystems are not well understood. The main objectives of the present study are (1) to determine the level of phytoavailable metal in soil and accumulation in A. rubrum, and (2) to compare the levels of genetic variation among and within A. rubrum populations from areas with different metal contents in a Northern Ontario region. The total heavy metal levels were found to be high but the availability of these metals were much lower. We found that red maple does not accumulate heavy metals in their leaves as other hardwood species. The translocation factors were 0.05, 0.21, 0.38, 0.90, and 2.8 for Cu, Ni, Fe, Zn, and Mg, respectively. The levels of genetic variation in red maple populations from reclaimed lands in Northern Ontario were moderate to high since the percentage of polymorphic loci varied between 51 and 67%. The mean values for observed number of alleles (Na), effective number of alleles (Ne), Nei's gene diversity (h), and Shannon's information index (I) were 1.60, 1.24, 0.15 and 0.24, respectively. The population differentiation (GST) among the fragmented populations was high (0.28) despite a high level of gene flow (Nm = 1.28). Nevertheless, all the populations within the targeted region were genetically closely related. A specific ISSR marker that was identified in all the samples from the reference sites was absent in most samples from metal contaminated. This specific band was cloned and sequenced. Overall, the present study confirms that red maple populations in Northern Ontario are genetically sustainable despite the high level of total metal content in soil.

Determination of DNA methylation associated with Acer rubrum (red maple) adaptation to metals: analysis of global DNA modifications and methylation‐sensitive amplified polymorphism

“…2013; Kalubi et al. 2015, 2016). Although the levels of total metals (Ni, Cu, and Zn) were high in contaminated sites, the bioavailable portion was small as reported in the previous studies (Nkongolo et al.…”

“…2014; Kalubi et al. 2015, 2016; Mehes‐Smith and Nkongolo 2015). It is expected that the expression of genes involved in metal avoidance and exclusion is variable within segregating and heterozygous A. rubrum populations targeted in the present study.…”

“…It represents over 30% of all tree species in the region (Kalubi et al. 2015). This species has been reported to be fairly resistant to municipal landfill leachates (Gordon et al.…”

“…2014; Kalubi et al. 2015). Unlike other hardwood species analyzed to date, A. rubrum does not accumulate metals in its leaves (Kalubi et al.…”

Differential levels of gene expression and molecular mechanisms between red maple (Acer rubrum) genotypes resistant and susceptible to nickel toxicity revealed by transcriptome analysis

“…The translocation of nickel from roots to aerial parts is also very small. This species can be therefore classified as a nickel avoider (Kalubi, Mehes-Smith, & Omri, 2016;Kalubi et al, 2015). A. sacharinium, a close relative of A. rubrum, stores Ni in its roots with limited translocation to other plant parts.…”