Exogenous abscisic acid application decreases cadmium accumulation in Arabidopsis plants, which is associated with the inhibition of IRT1-mediated cadmium uptake

Abstract

Cadmium (Cd) contamination of agricultural soils is an increasingly serious problem. Measures need to be developed to minimize Cd entering the human food chain from contaminated soils. We report here that, under Cd exposure condition, application with low doses of (0.1–0.5 μM) abscisic acid (ABA) clearly inhibited Cd uptake by roots and decreased Cd level in Arabidopsis wild-type plants (Col-0). Expression of IRT1 in roots was also strongly inhibited by ABA treatment. Decrease in Cd uptake and the inhibition of IRT1 expression were clearly lesser pronounced in an ABA-insensitive double mutant snrk2.2/2.3 than in the Col-0 in response to ABA application. The ABA-decreased Cd uptake was found to correlate with the ABA-inhibited IRT1 expression in the roots of Col-0 plants fed two different levels of iron. Furthermore, the Cd uptake of irt1 mutants was barely affected by ABA application. These results indicated that inhibition of IRT1 expression is involved in the decrease of Cd uptake in response to exogenous ABA application. Interestingly, ABA application increased the iron level in both Col-0 plants and irt1 mutants, suggesting that ABA-increased Fe acquisition does not depend on the IRT1 function, but on the contrary, the ABA-mediated inhibition of IRT1 expression may be due to the elevation of iron level in plants. From our results, we concluded that ABA application might increase iron acquisition, followed by the decrease in Cd uptake by inhibition of IRT1 activity. Thus, for crop production in Cd contaminated soils, developing techniques based on ABA application potentially is a promising approach for reducing Cd accumulation in edible organs in plants.

Inhibition of DNA demethylation enhances plant tolerance to cadmium toxicity by improving iron nutrition

“…This conclusion was further supported by our pharmacological study in which the treatment with 5-aza, a DNA methyltransferase inhibitor that could also result in DNA hypomethylation (Goffin & Eisenhauer, 2002;Griffin et al, 2016), aggravated Cd toxicity in the plants (Figure 3d could be classified as "avoidance" and "tolerance" strategies (Choppala et al, 2014). "Avoidance" by which plants prevent Cd entering into cells from contaminated medium, serves as a basic strategy to relieve Cd toxicity (Choppala et al, 2014;Fan et al, 2014). After Cd enters plant cells, "tolerance" strategy, which includes compartmentalization of Cd in the vacuole or cell walls and chelation of Cd by phytochelatins or metallothioneins, plays a major role in mitigating Cd toxicity (Lux et al, 2011).…”

“…Several plants have evolved protective mechanisms against Cd toxicity, which could be classified as “avoidance” and “tolerance” strategies (Choppala et al, ). “Avoidance” by which plants prevent Cd entering into cells from contaminated medium, serves as a basic strategy to relieve Cd toxicity (Choppala et al, ; Fan et al, ). After Cd enters plant cells, “tolerance” strategy, which includes compartmentalization of Cd in the vacuole or cell walls and chelation of Cd by phytochelatins or metallothioneins, plays a major role in mitigating Cd toxicity (Lux et al, ).…”

Abscisic acid-deficient sit tomato mutant responses to cadmium-induced stress

“…Taichung Native 1, TN1) (Hsu and Kao 2003). Additionally, a molecular mechanism of interaction between Cd and ABA has been clarified in Arabidopsis, with a decrease in Cd accumulation in the presence of exogenous ABA, by inhibiting the IRON-REGULATED TRANSPORTER 1 (IRT1) (Fan et al 2014), a broadspectrum transporter in roots, which is involved in the absorption of several other divalent cations, including Cd (Vert et al 2002). Additionally, we have been able to show that the mechanisms by which ABA interacts with Cd is followed by evident histological and biochemical alterations.…”

Plant ABC transporters: time for biochemistry?

“…These results therefore point towards the hypothesis that the pathogen-and lead-related phenotypes are indirect effects of the ABA-transport function of AtPDR12. Indeed, since then, several reports have linked ABA to both heavy metal tolerance and plant-pathogen responses [12][13][14][15]. This example highlights the importance of performing thorough and, most importantly, direct transport assays before assigning a substrate to an ABC transporter.…”