Metal hyperaccumulator plants are able to accumulate extremely high concentrations of Heavy Metals (HMs) in shoots, in contrast with non-accumulator species. Among them, the european species Noccaea caerulescens, member of the Brassicaeae family, represents an interesting model, because it shows a great variability between different ecotypes in metal tolerance and accumulation, considering, for instance, Zinc (Zn), Nickel (Ni) and Cadmium (Cd), alone or in combination. This work focused on the ecotype Monte Prinzera (MP, Italy) of N. caerulescens, autochthonous in a Natural Reserve in the Tosco-Emilian Appennins (Italy) characterized by serpentine soil; this particular ecotype is able to tolerate and accumulate Ni and Zn, a property that is shared with two other species of the same genus, i.e. N. goesingense and N. japonica. Molecular mechanisms responsible for Ni tolerance and accumulation are still unknown, although different genes seem to play a role in these processes. Metal transporter proteins are essential for metal homeostasis and different studies have demonstrated a fundamental role in HM tolerance and accumulation. In this work, we analysed and compared the response of N. caerulescens MP to different Ni concentrations with that of T. arvense (non-accumulator) and N. caerulescens ecotype Ganges (GA, Zn and Cd hyperaccumulator). Particularly, Real time PCR analysis was performed to evaluate the response of two vacuolar transporters, MTP1 and NRAMP4, and a plasma membrane transporter, ZNT1, to different Ni concentrations. This assay demonstrated that MTP1, which encode for a vacuolar Zn transporter, was highly expressed, suggesting a role in Ni tolerance and/or accumulation. In both GA and MP ecotypes, at least two different forms of MTP1 have been identified, possibly encoding proteins with different metal specificity; the shorter version of MTP1 lacks the highly conserved cytoplasmic His-loop necessary for metal binding specificity. Protoplasts transfection with constructs harbouring the two MTP1 coding sequences fused to a GFP reporter is ongoing to visualize the subcellular localization of both proteins. Tests with yeast mutants will be performed in order to determine whether the genes under investigation have a different role in heavy metal detoxification.
5.42 IDENTIFICATION AND ANALYSIS OF GENES INVOLVED IN NICKEL TOLERANCE IN NOCCAEA CAERULESCENS
ZORZI, GIANLUCA;DAL CORSO G.;FURINI A.
2017-01-01
Abstract
Metal hyperaccumulator plants are able to accumulate extremely high concentrations of Heavy Metals (HMs) in shoots, in contrast with non-accumulator species. Among them, the european species Noccaea caerulescens, member of the Brassicaeae family, represents an interesting model, because it shows a great variability between different ecotypes in metal tolerance and accumulation, considering, for instance, Zinc (Zn), Nickel (Ni) and Cadmium (Cd), alone or in combination. This work focused on the ecotype Monte Prinzera (MP, Italy) of N. caerulescens, autochthonous in a Natural Reserve in the Tosco-Emilian Appennins (Italy) characterized by serpentine soil; this particular ecotype is able to tolerate and accumulate Ni and Zn, a property that is shared with two other species of the same genus, i.e. N. goesingense and N. japonica. Molecular mechanisms responsible for Ni tolerance and accumulation are still unknown, although different genes seem to play a role in these processes. Metal transporter proteins are essential for metal homeostasis and different studies have demonstrated a fundamental role in HM tolerance and accumulation. In this work, we analysed and compared the response of N. caerulescens MP to different Ni concentrations with that of T. arvense (non-accumulator) and N. caerulescens ecotype Ganges (GA, Zn and Cd hyperaccumulator). Particularly, Real time PCR analysis was performed to evaluate the response of two vacuolar transporters, MTP1 and NRAMP4, and a plasma membrane transporter, ZNT1, to different Ni concentrations. This assay demonstrated that MTP1, which encode for a vacuolar Zn transporter, was highly expressed, suggesting a role in Ni tolerance and/or accumulation. In both GA and MP ecotypes, at least two different forms of MTP1 have been identified, possibly encoding proteins with different metal specificity; the shorter version of MTP1 lacks the highly conserved cytoplasmic His-loop necessary for metal binding specificity. Protoplasts transfection with constructs harbouring the two MTP1 coding sequences fused to a GFP reporter is ongoing to visualize the subcellular localization of both proteins. Tests with yeast mutants will be performed in order to determine whether the genes under investigation have a different role in heavy metal detoxification.
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