Chromium accumulation and changes in plant growth, selected phenolics and sugars of wild type and genetically modified Nicotiana langsdorffii

Chromium accumulation, dry weight (DW) biomass yield, water content and concentrations of someselected phenolic compounds and carbohydrates were determined in root and shoot of Nicotiana langs-dorffii, either wild type (WT) or genetically modified by the insertion of GR and rolC genes, in response tothe presence of Cr(VI) in the growth medium. A biomass decrease was observed for WT plants, but not for GR and rolC transformations, in response to Cr(VI) in the growth medium, highlighting a stress situation only in WT line. Shoot chromium concentrations were in all cases about 300 mg kg−1DW. In root higher concentrations were found in rolC than in GR and WT (3843, 2600 and 2751 mg kg−1DW, respectively). Based on the DW biomass, GR and WT accumulated higher chromium quantities than rolC, both in root(330 and 424 versus 85 g Cr per plant) and shoot (282 and 275 versus 121 g Cr per plant). Therefore,GR should be preferred to WT as a promising candidate for chromium phytoremediation. Metabolic shifts of sugars and phenolics were generally observed in response to either gene insertionsor exposure to Cr(VI), being the latter more related to the resistance to Cr(VI) than the former.