Synergetic effects of DA-6/24-EBL and NTA on uptake, subcellular distribution and chemical form of Cd in Amaranthus hybridus L

Abstract

ABSTRACT Plant growth regulators(PGR)-assisted phytoremediation is a technique which could improve the efficiency of heavy metal accumulation in hyperaccumulator plants. The aim of this study was to explore the effects of PGR combination with nitrilotriacetic acid (NTA) on Cd extraction and distribution in Cd hyperaccumulator. To achieve this objective, a pot experiment was carried out to investigate the effects of the diethyl aminoethyl hexanoate (DA-6) and 24-epibrassinolide (24-EBL) and/or NTA on Cd phytoextraction, subcellular distribution and chemical forms in Amaranthus hybridus L. Results showed that NTA significantly decreased plant biomass production, but increased shoot and root Cd concentrations. Foliar spray containing DA-6 and 24-EBL alone increased both plant biomass and shoot and root Cd concentrations, the most pronounced effects observed were with 1 μM of DA-6. The combination of DA-6 and NTA inhibited toxicity and synergistically affected Cd uptake/accumulation. The addition of NTA alone enhanced Cd levels in soluble and cellular organelle fractions, whilst DA-6 and 24-EBL counteracted the toxic effects of Cd by promoting Cd retention in the cell walls, with 1 μM of DA-6 being the most effective dose. The NTA promoted metal mobility in shoots, resulting in increased Cd toxicity and stunted plant growth. In contrast, DA-6 and 24-EBL significantly reduced Cd mobility in plants. These results demonstrate that DA-6/24-EBL with NTA overcomes the detrimental effects of NTA on plant growth. Of the concentration ranges assessed, NTA + 1 μM DA-6 was optimal for the improving the remediation efficiency in A. hybridus.