Production of organic acids and adsorption of Cd on roots of durum wheat (Triticum turgidum L. var. durum)

Abstract

A number of isolines of durum wheat (Triticum turgidum var durum) differ in their translocation of Cd. In the field, the high isolines accumulate twice the Cd in leaves and grain when compared to the low isolines. The hypothesis that differential accumulation of Cd is associated with differential production of organic acids was tested by measuring Cd content in tissues, Cd partitioning within the root, and organic acids in tissues. In solution culture, the high and low isolines of W9261-BG did not differ in any of the variables measured. Within W9260-BC, the low isoline had half the Cd in its shoot, 30% more tightly-bound Cd in the root and higher concentrations of fumaric, malic, and succinic acids in the root compared to the high isoline. Differential Cd accumulation may be linked to differential adsorption and retention of Cd in the roots of the low Cdaccumulating isolines, possibly via chelation with organic acids.

Cadmium uptake and translocation in durum wheat varieties differing in grain-Cd accumulation

“…In contrast, the Cd-concentration of spikes was always higher in Svevo. In Creso, moderate grain- Cd accumulation seemed to be associated with high root retention (Adeniji et al 2010), while, in Svevo, high accumulation could be due to active Cd translocation to shoot and grain, probably related to better mineral use efficiency (Pampana et al 2007, Kubo et al 2008. Cadmium content and partitioning.…”

“…Indeed, durum wheat, from which pasta is prepared, accumulates more Cd in grain than bread wheat (Stolt et al 2003, Greger andLöfsted 2004). The Codex alimentarius commission proposed a limit of 0.2 mg Cd/kg for wheat grain products, but higher Cd-concentrations were recorded in grain of wheat crops grown worldwide (Kubo et al 2008, Adeniji et al 2010.…”

“…Greger and Landberg (2008) found a relationship between high accumulation and the exudation of organic acids that release Cd from soil particles, while Shenker et al (2001) found that phytosiderophores ameliorated Cd mobilisation in soil, but not plant uptake. It was also hypothesised that low and high grain-Cd accumulation depends on differential Cd binding to organic acids in roots (Stolt et al 2003, Adeniji et al 2010. In bread wheat, high grain-Cd was associated with elevated Cd uptake during early growth, and with high root to shoot translocation, while in durum wheat it was associated with high translocation to the shoot, but not with high uptake (Zhang et al 2002, Greger and Löfsted 2004, Kubo et al 2011.…”

Absorption and distribution of cadmium of three maize hybrids in three environments

“…Therefore, the low grain Cd accumulation could be due to several factors: 1) uptake and translocation limitations generated in the root (Adeniji et al, 2010;Yang et al, 2014), which suggests that maize plants appear to have more efficient defence mechanisms than other crops to deal with Cd toxicity, including its accumulation in the root (Adeniji et al, 2010); 2) soil available Zn concentration since Zn is an antagonist to plant Cd uptake (Tanwir et al, 2015); and 3) low Cd concentration could be attributable to the high agronomic efficiency of nutrient use (kg DM produced per kg of applied nutrient) obtained in this experiment (data not shown) compared with other studies cited in the literature, which implied an overall nutrient dilution effect (Fahad et al, 2015). However, applying increasing Cd rates produced an increase of more than 100% in maize grain Cd accumulation when compared with the control with no applied Cd (Arduini et al, 2014;Yang et al, 2014).…”

“…Another factor affecting both Cd availability and uptake by plants is root exudation of organic acids, such as citrate and malate (Adeniji et al, 2010;Seshadri et al, 2015). White lupin (Lupinus albus L.) is defined as a species that exudes elevated levels of organic acids that can increase soil Cd availability, but restricts Cd transport from the roots to the stems and grains (Tejo et al, 2016).…”