Effects of iron deficiency on subcellular distribution and chemical forms of cadmium in peanut roots in relation to its translocation

• Peanut cultivars differ in shoot Cd accumulation and subcellular distribution.
• Fe deficiency increases Cd accumulation but decreases its translocation to shoots.
• Fe deficiency alters subcellular distribution and chemical forms of Cd in roots.
• High proportion of Cd in soluble fraction contribute to low Cd accumulation in shoot.
• High proportion of NaCl extractable Cd associated with decreased Cd translocation.

Effects of iron deficiency on subcellular distribution and chemical forms of Cd in four peanut (Arachis hypogaea L.) cultivars were investigated by a hydroponics experiment, at low Cd level (0.2 μM CdCl2). The results show that, compared with high Cd accumulating cultivars, the low Cd accumulating cultivars show higher biomass production, more chlorophyll, and less Cd accumulation in shoots. Higher proportion of Cd in the soluble fraction was also observed in low Cd accumulating cultivars that may contribute to low Cd accumulation in their shoots. Fe deficiency increases Cd uptake and accumulation in plants, but decreases Cd translocation from roots to shoots. It was also observed that Fe deficiency increase the proportion of Cd in the soluble fraction and the proportion of NaCl extractable Cd, which were negatively correlated with shoot Cd concentration. The percentage of NaCl extractable Cd was negatively and exponentially related to the percentage of Cd in shoots and translocation factors of Cd to shoots. It seems that a high proportion of Cd in the soluble fraction (mainly in vacuoles) and a high proportion of NaCl extractable Cd (pectate and protein-bound Cd) are responsible for the decreased Cd translocation by Fe deficiency.