![]() ![]() Mn toxicity is favored in acid soils (Pendias and Pendias, 1992). Thus, Mn has two roles in the plant metabolic processes: as an essential micronutrient and as a toxic element when it is in excess (Kochian et al, 2004 Ducic and Polle, 2005). ![]() However, its excess seems also to be particularly damaging to the photosynthetic apparatus (Mukhopadhyay and Sharma, 1991). Its deficit is dangerous for chloroplasts because it affects the water-splitting system of photosystem II (PSII), which provides the necessary electrons for photosynthesis (Buchanan, 2000). In plants, it participates in the structure of photosynthetic proteins and enzymes. Manganese (Mn) is an essential micronutrient in most organisms. Keywords: Manganese, Mn toxicity, resistance mechanisms The forms and dynamics of this element in soils and the importance of the acidity for this dynamic and availability for plants are also given. The purpose of this review is to show the role of Mn as an essential micronutrient and as a toxic element to higher plants as well as to their transport and tolerance mechanisms. A key role of antioxidative systems in plants in relation to high Mn amounts has also been reported as a defense mechanism. When Mn is inside the cells, mechanisms that can tolerate this toxicity are also observed, being important the compartmentalization of this metal in different organdíes of shoot and leaf plant cells. Some studies on Mn toxicity and Mn translocation from soil to plant cells in Mn 2+ form have demonstrated their importance under low pH and redox potential conditions in the soil. Mn phytotoxicity is manifested in a reduction of biomass and photosynthesis, and biochemical disorders such as oxidative stress. ![]() Nevertheless, an excess of this micronutrient is toxic for plants. Alberdi 4ġPrograma de Doctorado en Ciencias de Recursos Naturales, Universidad de La Frontera, Casilla 54-D, Temuco, Chile.ĢCenter of Plant-Soil Interaction and Natural Resources Biotechnology,Scientific and Technological Bioresource Nucleus (BIOREN), Universidad de La Frontera, Casilla 54-D, Temuco, Chile,ģDepartment of Biology and the Biotron, University of Western Ontario, London, Ontario, N6A 5B7 Canada.ĤDepartamento de Ciencias Químicas, Center of Plant-Soil Interaction and Natural Resources Biotechnology - Scientific and TechnologicalBioresource Nucleus (BIOREN), Universidad de La Frontera, Casilla 54-D, Temuco, Chile.Corresponding author: is an essential element for plants, intervening in several metabolic processes, mainly in photosynthesis and as an enzyme antioxidant-cofactor. MANGANESE AS ESSENTIAL AND TOXIC ELEMENT FOR PLANTS: TRANSPORT, ACCUMULATION AND RESISTANCE MECHANISMS ![]()
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