Improved cadmium uptake and accumulation in the hyperaccumulator Sedum alfredii: the impact of citric acid and tartaric acid

Abstract

Abstract:The elucidation of a natural strategy for metal hyperaccumulation enables the rational design of technologies for the clean-up of metal-contaminated soils. Organic acid has been suggested to be involved in toxic metallic element tolerance, translocation, and accumulation in plants. The impact of exogenous organic acids on cadmium (Cd) uptake and translocation in the zinc (Zn)/Cd co-hyperaccumulator Sedum alfredii was investigated in the present study. By the addition of organic acids, short-term (2 h) root uptake of 109 Cd increased significantly, and higher 109 Cd contents in roots and shoots were noted 24 h after uptake, when compared to controls. About 85% of the 109 Cd taken up was distributed to the shoots in plants with citric acid (CA) treatments, as compared with 75% within controls. No such effect was observed for tartaric acid (TA). Reduced growth under Cd stress was significantly alleviated by low CA. Long-term application of the two organic acids both resulted in elevated Cd in plants, but the effects varied with exposure time and levels. The results imply that CA may be involved in the processes of Cd uptake, translocation and tolerance in S. alfredii, whereas the impact of TA is mainly on the root uptake of Cd.

Exogenous glycinebetaine alleviates the detrimental effect of Cd stress on perennial ryegrass

“…In addition, tartaric and oxalic acid chelated the heavy metal ions which are detrimental to plants (Li et al 2007). Our results also illustrated that tartaric acid and oxalic acid were increased after GB application and were correlated with the heavy metal stress tolerance in perennial ryegrass (Lu et al 2013). Organic acids excreted by roots could reduce the bio-availability of Cd, and protect the roots from toxicity effects (Liao and Xie 2004;Schwab et al 2005).…”

The role of organic acids in heavy metal tolerance in plants

“…In a study on Brassica napus plants in water culture, it was found that citrate application at a concentration of 2.5 mM in medium containing 10 or 50 µm Cd contributed to the 1.5-times increase in the accumulation of Cd in roots, stems, and leaves of canola (Ehsan et al, 2014). Stimulation of Cd accumulation under the effect of exogenous citrate (but not tartrate) was shown for Cd/Zn hyperaccumulator Sedum alfredii (Lu et al, 2013) and for Spinacia oleracea plants (Degryse, Smolders, and Parker, 2006).…”

“…Durrett, Gassmann, and Rogers (2007) emphasize that citrate plays a role in the chelation of Fe 2+ during the transport of these ions in the xylem, while FRD3 mediates the efflux of citrate to the root vessels to maintain the transfer of iron to the shoot. Data have been presented on joint xylem transport of Cd and citrate for Zn/Cd hyperaccumulator Sedum alfredii, which increases the transfer and accumulation of Cd in the leaves (Lu et al, 2013).…”

“…Less information is available about the specificity of Cd hyperaccumulation; however, there is evidence that in the Zn/Cd hyperaccumulator Sedum alfredii, citrate is involved in Zn hyperaccumulation and Zn tolerance (Yang et al, 2006), whereas Cd in shoots is up to 85% associated with malate and only 15% with citrate (Lu et al, 2013). A positive correlation was found between citrate content and water soluble Cd content in the leaves of Cd hyperaccumulator Solanum nigrum L., which suggests that citrate is responsible for high accumulation of Cd in the leaves of this plant and the plants' resistance to it (Sun, Zhou, and Jin, 2006).…”

Variation in copper and zinc tolerance and accumulation in 12 willow clones: implications for phytoextraction

“…Phytoremediation is the process of using trees, shrubs, and grasses to de-contaminate soil and water, and is considered to be a promising, cost-effective solution to heavy-metal pollution (Licht and Isebrands, 2005;Vangronsveld et al, 2009;Xing et al, 2012;Lu et al, 2013). Generally, phytoremediation and especially phytoextraction rely on plants known as hyperaccumulators; however, these are species that often have a low biomass and slow growth rate, leading to a long time periods required for metal removal (Tanhan et al, 2007).…”