Nitrate facilitates cadmium uptake, transport and accumulation in the hyperaccumulator Sedum plumbizincicola

Abstract

The aims of this study are to investigate whether and how the nitrogen form (nitrate (NO 3 -) versus ammonium (NH 4 + )) influences cadmium (Cd) uptake and translocation and subsequent Cd phytoextraction by the hyperaccumulator species Sedum plumbizincicola. Plants were grown hydroponically with N supplied as either NO 3 -or NH 4 + . Short-term (36 h) Cd uptake and translocation were determined innovatively and quantitatively using a positron-emitting 107 Cd tracer and positron-emitting tracer imaging system. The results show that the rates of Cd uptake by roots and transport to the shoots in the NO 3 -treatment were more rapid than in the -promoted the major steps in the transport route followed by Cd from solution to shoots in S. plumbizincicola, namely its uptake by roots, xylem loading, root-to-shoot translocation in the xylem and uploading to the leaves. S. plumbizincicola prefers NO 3 -nutrition to NH 4 + for Cd phytoextraction.

Influence of nitrogen form on the phytoextraction of cadmium by a newly discovered hyperaccumulator Carpobrotus rossii

“…However, in hydroponic experiments, supplying NO 3 − doubled Cd concentration in the shoots of Noccaea caerulescens, compared with NH 4 + supply (Xie et al 2009). Similar results were found for Sedum plumbizincicola in solution culture; NO 3 − stimulated Cd uptake by roots, xylem loading, shoot-to-root translocation, and uploading to the leaves and thus enhanced Cd phytoextraction (Hu et al 2013). Monsant et al (2008) showed that NO 3 − nutrition improved Zn phytoextraction in solution culture by increasing the biomass and Zn concentration of shoots of N. caerulescens.…”

“…The results are inconsistent with those of Xie et al (2009) and Hu et al (2013). By using a positronemitting 107 Cd tracer, Hu et al (2013) showed that Cd transport was 1.5-fold and 3.7-fold faster in the roots and shoots, respectively, in the Cd hyperaccumulator S. plumbizincicola supplied with NO 3 − than with NH 4 + . The concentration of Cd was 2.63 times higher in shoots of the NO 3 − -than NH 4 + -fed plants in nutrient solution.…”

Phytoremediation of Heavy Metals: The Use of Green Approaches to Clean the Environment

“…The Cd and P phytoavailability of kangkong ( Ipomoea aquatica Forsk.) with Alfred stonecrop ( Sedum alfredii Hance) can be induced while inoculated with arbuscular mycorrhizal fungi (Hu et al 2013 ).…”

“…Whereas, in case of hyperaccumulators roots effi ciently transport metals to the shoots, e.g., in case of Sedum alfredii ecotype, xylem plays an important role in Cd uptake as compared to the non-hyperaccumulating ecotypes (Lu et al 2009 ). The translocation of Cd uptake and Cd phytoextraction has been recently studied by Hu et al ( 2013 ) in another species of Sedum plumbizincicola . In this study they found that the rate of Cd uptake was more from roots to the shoots when NO 3-treatment was given.…”

Burkholderia sp. cadmium tolerance mechanism and its influence in phytoremediation

“…Therefore,the presence of Cd can also not influence MT expression, this was described in tomato (present work and OUZIAD et al, 2005) and sugarcane (GUO et al, 2013), only the combination Nitrogen is an essential macronutrient, responsible for the biosynthesis of all aminoacid, protein and enzymes, despite of the decrease in nitrogen content in the presence of the bacteria, inoculated plants grew more, presenting a higher biomass, and consequently a total protein and nitrogen higher than non inoculated plants. Hu et al (2013) reported that nitrate (not ammonium) induce Cd and Zn uptake (increasing fitoextraction). In the pot assay of the present work, we used a fertilizer with nitrate, enhancing Cd uptake, finding a high concentration of Cd in leaves, the addition of SCMS54:gfpdecreased Cd absorption, decreasing phytoextraction potential, but on the other hand, increasing plant tolerance.…”