Establishment of transgenic tobacco hairy roots expressing basic peroxidases and its application for phenol removal

Transgenic hairy root (HR) systems constitute an interesting alternative to improve the efficiency of phytoremediation process. Since peroxidases (Px) have been associated with phenolic compounds removal, in the present work, transgenic tobacco HR, which expressed basic Px genes from tomato (tpx1 and tpx2), were established and assayed for phenol removal. Tobacco HR clones were obtained, including those transgenic for TPX1 or TPX2, those double transgenic (DT) for both Px and the corresponding controls. Based on growth index, the presence of rol C sequence, tpx1 and/or tpx2 genes and the coded proteins, as well as Px activity determinations, we selected 10 tobacco HR clones for phenol removal assays. The removal efficiencies were high for all the HR, although, some transgenic HR showed significantly higher removal efficiencies compared with controls. The results demonstrate that TPX1 is involved in phenol removal not only when it was overexpressed in tomato, but also when it was expressed in other plant, such as tobacco. The higher efficiency of TPX2 transgenic HR showed that this Px also participates in the process. The contribution of other mechanisms (adsorption, H2O2 independent enzymatic processes) could be considered depreciable, which establishes the great implication of Px in phenol removal.