Arsenic (As) is potentially toxic to plants and animals. Because of its chemical similarity to the plant-available form of phosphorus, As can be taken up by roots and transported within the plant. It can thus accumulate in edible plant parts and enter the food chain, posing a risk to human health. One of the plants that causes a risk of As intake is peanut (Arachis hypogaea L.), which is an important crop in the province of Córdoba, Argentina, where several cultivated areas contain high background concentrations of As. In addition, occasional local flooding episodes further aggravate the As-contamination problem. The aim of this thesis was to evaluate the uptake and partitioning of As in the peanut plant and to determine the tissue-specific localisation of As in roots and nodules under flooded and non-flooded conditions. Using X-ray fluorescence, the highest concentration of As was measured in roots, followed by nodules, and the lowest concentration was measured in stems and leaves. Tissue-specific localisation of As was determined using micro-particle-induced X-ray emission. No tissue-specific accumulation of As was observed in nodules. In roots, most As was accumulated in specific parts of the vascular tissue, where we observed co-localisation of As and sulphur (S), suggesting the complexation of As with sulphydryl groups of peptides, which presumably limits As mobility within the plant. Flooding did not affect As uptake but resulted in the formation of iron-plaque on the root surface, which represents a barrier to which As can be adsorbed. The proposed strategies to reduce the uptake and transport of As to the aerial parts of the plant are thus the supplementation of peanut crop with S and flooding management. Further, ideally field investigations are required to determine these two potential practices as efficient in a realistic agricultural situation.
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