Phytoextraction of lead (Pb) is a challenging task due to its extremely low mobility within soil and plant systems. In this study, we tested the influence of some novel chelating agents for Pb-phytoextraction using sunflower. The Pb was applied at control (0.0278mM) and 4.826mM Pb as Pb(NO3)2 through soil-spiking. After 10days of Pb addition, four different organic ligands (aspartic, ascorbic, tartaric, and pantothenic acids) were added to the soil at 1mM concentration each. respectively. In the absence of any chelate, sunflower plants grown at 4.826mM Pb level accumulated Pb concentrations up to 104µgg-1 DW in roots, whereas 64µgg-1 DW in shoot. By contrast, tartaric acid promoted significantly Pb accumulation in roots (191µgg-1 DW; + 45.5%) and shoot (131.6µgg-1 DW; + 51.3%). Pantothenic acid also resulted in a significant Pb-uptake in the sunflower shoots (123µgg-1 DW; + 47.9%) and in roots (177.3µgg-1 DW; + 41.3%). The least effective amongst the chelates tested was aspartic acid, but it still contributed to + 40.1% more Pb accumulation in the sunflower root and shoots. In addition, plant growth, biochemical, and ionomic parameters were positively regulated by the organic chelates used. Especially, an increase in leaf Ca, P, and S was evident in Pb-stressed plants in response to chelates. These results highlight that the use of biocompatible organic chelates positively alters plant physio-biochemical traits contributing to higher Pb-sequestration in sunflower plant parts.
Read full abstract