Expression of Nickel and Copper Resistance Genes in Hardwood Populations from a Metal-Contaminated Region.

Metal toxicity is a major abiotic stressor of plants. It has been established that changes in genetic variation occur very rapidly in plants in response to environmental stressors such as increased levels of metals. The objective of the study was to assess the level of gene expression of candidate genes for nickel and copper resistance. We have identified genes associated with nickel and copper resistance in model and non-model plant species. They include for nickel 1-aminocyclopropane-1-carboxylic acid deaminase (ACC), high affinity nickel transporter family protein (AT2G16800), glutathione reductase (GR), glutathione-s-transferase (GST), iron-regulated protein (IREG), nicotianamine synthase (NAS3), metal transporters (NRAMP), putative transmembrane protein (TMP), serine-acetyltransferase (NAS3), thioredoxin family protein, a zinc transporter of Arabidopsis thaliana (ZAT11), and  Ton B receptor/family protein. Genes involved in Cu resistance include copper transporter protein (COPT1), multi-drug resistance associated protein (MRP4), metallothionein (MT2B) and copper-transporting ATPase (RAN1).  We have investigated the expression of these genes in hard wood populations of Betula papyrifera, Quercus rubra, Acer rubrum, and Populus tremuloides under metal stress conditions. High expression of some of these genes  in genotypes exposed to high doses of nickel under growth chamber conditions was observed. No association between nickel and copper contamination and gene expression was found in samples from metal contaminated sites under field conditions. Results of genes regulation will be discussed