Effect of cadmium on the physiological parameters and the subcellular cadmium localization in the potato (Solanum tuberosum L.)

• The highest Cd accumulation organ was the leaf of the potato.
• Cd mainly deposited in the spongy and palisade tissues of the leaf.
• Cd was detected in the cortex and the adjacent phloem of the stem.
• Cd was detected on the surface of the starch granules of the tuber.
• Cd in the leaf induced the increase of MDA and reduction of the chlorophyll.

The pollution of agricultural soils with cadmium (Cd) has become a serious problem worldwide. The potato (Solanum tuberosum L.) was used to investigate how different concentrations of Cd (1, 5, and 25 mg kg−1) affected the physiological parameters and the subcellular distribution of Cd in the potato. The analyses were conducted using scanning electron microscopy coupled with energy dispersive X-ray (SEM-EDX). The results suggest that the leaf is the organ with the highest accumulation of Cd. The malondialdehyde (MDA) content increased and the chlorophyll content decreased in response to high level of Cd. The SEM-EDX microanalysis revealed that Cd was primarily deposited in the spongy and palisade tissues of the leaf. Furthermore, Cd was also detected in the cortex and the adjacent phloem and was observed inside the intercellular space, the interior surface of the plasma membrane, and on the surface of the elliptical starch granules in the tubers of the potato. Although low concentrations of Cd migrated from the root to the tuber, the accumulation of Cd in the tuber exceeded the standard for food security. Therefore, the planting of potato plants in farmland containing Cd should be seriously evaluated because Cd-containing potatoes might present high health risk to humans.