Nickel translocation, toxicity, and its effect on the expression of genes associated with nickel resistance in red pine (Pinus resinosa)

Abstract

The main objectives of this study were to 1) investigate metal accumulation and translocation in Pinus spp ., 2) evaluate the level of P. resinosa resistance to nickel; and 3) determine the effects of different concentrations of nickel on gene expression in Pinus resinosa . Seedlings were treated with different concentrations of nickel nitrate (16 mg, 160 mg, and 1,600 mg of nickel per 1 kg of dry soil) and corresponding salt controls in growth chamber screening tests. In general, collected data revealed that P. resinosa is resistant to nickel. The expression of 1-aminocyclopropane-1-carboxylic acid deaminase (ACC deaminase), glutathione-S-transferase (GST), High-affinity Ni transporter (NiCoT or AT2G16800), and natural resistance-associated macrophage protein 3 (NRAMP3) and Serine acetyltransferase (SAT) were analyzed using RT-qPCR. The expression of ACC in samples treated with 1,600 mg/kg of Ni was significantly supressed as it was half of that observed in the water control samples. AT2G16800, and SAT expression were significantly upregulated under 16 mg/kg and 160 mg/kg Ni treatments. But the expression of these genes was repressed in seedlings exposed to 1,600 mg/kg of Ni. The 1,600 mg/kg of Ni induced a GST expression level that was 6.65-fold greater than that of the water control. Overall, low level of nickel ions induce an increase in the expression of ACC, GST, AT2G16800, NRAMP3, and SAT. The levels of bioavailable Ni in soils contaminated with metals was low while Ni concentrations in roots, branches, and needles of P. resinosa exposed to Ni for several years were similar.