Effects of nickel toxicity on expression of genes associated with nickel resistance in white spruce (Picea glauca): Nickel translocation in plant tissues.

Abstract

The main objectives of this study were to determine a) nickel accumulation and translocation within tissues and b) nickel effects on gene expression in white spruce (Picea glauca). The results of the study revealed that even at the highest dose of 1,600 mg of Ni /kg of soil, there was no physical evidence of toxicity to P. glauca seedlings screened. P. glauca was found to be a nickel avoider, as the bioaccumulation factor as well as translocation factors for roots to aerial tissues were less than 1.0. Expression of SAT, GR, ACC, NAS, Nramp, and AT2G16800 genes in roots and needles were investigated. Expression of ACC and NRAMP were upregulated in the presence of nickel, whereas GR was downregulated at the lowest dose (150 mg/kg) and upregulated at the highest dose (1,600 mg/kg). There were significant differences between ACC expression in roots and needles. The results of the present study also show that that potassium nitrate (a common plant fertilizer) does have an effect on gene expression and can lead to toxicity in P. glauca plants at high concentrations. Overall, the findings of this research suggest that the low level of bioavailable nickel in mining sites in Northern Ontario and other mining regions can trigger changes in gene expression.