Kalubi K N, Mehes-Smith M, Narendrula R, Michael P, Omri A
Department of Biology, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON, P3E-2C6, Canada.
Ecotoxicology. 2015 Apr;24(3):636-47. doi: 10.1007/s10646-014-1411-7. Epub 2015 Jan 6.
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.
红枫（Acer rubrum）是北美东部分布最广的落叶（硬木）树种之一。它是安大略省北部土地复垦后占主导地位的树种之一。迄今为止，采矿活动产生的重金属污染对陆地生态系统的影响尚不清楚。本研究的主要目的是：（1）确定土壤中植物可利用金属的含量以及红枫中的积累量；（2）比较安大略省北部不同金属含量地区红枫种群之间以及种群内部的遗传变异水平。研究发现，重金属总量较高，但这些金属的有效性要低得多。我们发现，红枫不像其他硬木树种那样在叶片中积累重金属。铜、镍、铁、锌和镁的转运因子分别为0.05、0.21、0.38、0.90和2.8。安大略省北部开垦土地上红枫种群的遗传变异水平为中度至高度，因为多态位点的百分比在51%至67%之间变化。观察到的等位基因数（Na）、有效等位基因数（Ne）、Nei基因多样性（h）和香农信息指数（I）的平均值分别为1.60、1.24、0.15和0.24。尽管基因流水平较高（Nm = 1.28），但碎片化种群之间的种群分化（GST）仍然很高（0.28）。然而，目标区域内的所有种群在遗传上密切相关。在参考地点的所有样本中都能识别出的一个特定ISSR标记，在大多数受金属污染的样本中都不存在。这个特定条带被克隆并测序。总体而言，本研究证实，尽管土壤中金属总含量较高，但安大略省北部的红枫种群在遗传上是可持续的。
