Expression of A rabidopsis acyl- CoA-binding proteins AtACBP1 and AtACBP4 confers Pb( II) accumulation in B rassica juncea roots.

In A rabidopsis thaliana, the expression of two genes encoding acyl- CoA-binding proteins ( ACBPs) AtACBP1 and AtACBP4, were observed to be induced by lead [ Pb( II)] in shoots and roots in qRT- PCR analyses. Quantitative GUS ( β-glucuronidase) activity assays confirmed induction of AtACBP1pro::GUS by Pb(II). Electrophoretic mobility shift assays ( EMSAs) revealed that Pas elements in the 5′-flanking region of AtACBP1 were responsive to Pb( II) treatment. AtACBP1 and AtACBP4 were further compared in Pb( II) uptake using B rassica juncea, a potential candidate for phytoremediation given its rapid growth, large roots, high biomass and good capacity to accumulate heavy metals. Results from atomic absorption analyses on transgenic B . juncea expressing AtACBP1 or AtACBP4 indicated Pb( II) accumulation in roots. Subsequent Pb( II)-tracing assays demonstrated Pb( II) accumulation in the cytosol of root tips and vascular tissues of transgenic B . juncea AtACBP1-overexpressors ( OXs) and AtACBP4- OXs and transgenic A rabidopsis AtACBP1- OXs. Transgenic A rabidopsis AtACBP1- OXs sequestered Pb( II) in the trichomes and displayed tolerance to hydrogen peroxide ( H2 O2) treatment. In addition, AtACBP1 and AtACBP4 were H2 O2-induced in the roots of wild-type A rabidopsis, while lipid hydroperoxide ( LOOH) measurements of B . juncea AtACBP1- OX and AtACBP4- OX roots suggested that AtACBP1 and AtACBP4 can protect lipids against Pb( II)-induced lipid peroxidation. [ABSTRACT FROM AUTHOR]