Coupling Nicotiana tabaccum transgenic plants with Rhizophagus irregularis for phytoremediation of heavy metal polluted areas

Abstract

Several studies have shown that hairy roots (HRs) can increase the phytoextraction of organic and inorganic pollutants. In addition, microorganisms colonizing the rhizosphere of hairy roots have demonstrated the efficacy of HRs either in removing or in stabilizing of pollutants. This growth chamber study aimed to determine the effect of colonization by the arbuscular mycorrhizal (AM) fungus (Rhizophagus irregularis) on the HRs of tobacco (Nicotiana tabaccum L. cv. Virginia gold) under heavy metals (Cu, Pb and Zn) conditions. Seedlings of N. tabacum were grown in contaminated substrate without infection caused by Agrobacterium rhizogenes expressed in the form of HRs disease, a second one with infection, and the third treatment contained AM fungus beside the A. rhizogenes infection. In the order they have been described, these treatments were coded with C, CT and CTM. The experiment demonstrated that HRs mutants resisted better in terms of higher biomass content in the contaminated soil than the normal plants. Even more, the transgenic plants also had a very strong interaction with mycorrhizal fungi. Thus, soil respiration, biomass and some biochemical variables such as assimilating pigments, protein content and lipid peroxidation indicate a decrease in stress due to the presence of heavy metals in the CTM treatment. Furthermore, CTM treatment significantly alleviated the concentration of toxic elements in plants, compared with the CT treatment, in which a significant increase was registered when compared to treatment C.