PLANT TOLERANCE TO HEAVY METALS, A RISK FOR FOOD TOXICITY OR A MEANS FOR FOOD FORTIFICATION WITH ESSENTIAL METALS: THE ALLIUM SCHOENOPRASUM MODEL

摘要

There is a duality in plant tolerance and response to heavy metal stress. On one hand tolerant plants having heavy metal hyper accumulation potential could be beneficial in phytoremediation for clean-up of soil and water; on the other hand tolerant food crops, if exposed to heavy metals in their growth medium, may be dangerous as carriers of toxic metals in the food chain leading to food toxicity. Tolerant food crops could also be used for enrichment of the diet with essential metals. Heavy metal stress causes oxidative damage, but some reactive oxygen species (ROS) can participate in signal transduction pathways. A new hypothetical mechanism for the interaction of cupric ions and ascorbic acid with proteins in response to metal stress is presented. The dualities mentioned above are discussed. Allium schoenoprasum (Chives) is the model plant to be presented. Like other members of the Allium genus it has a wide spectrum of sulfur-containing compounds in high concentrations, this may render it more tolerant to heavy metals. Some of these compounds may function as reductants and/or chelators to prevent the toxic effect of the metal. The results presented, point to chives phytoremediation potential, but also to the potential risk in accumulation of heavy metals in a commonly edible plant.