Oxidative Stress in Soybean: Role of Iron.

GALATRO A; PUNTARULO S

Soybeans: Cultivation Uses and Nutrition

Nova Publishers

Lugar: New York, USA; Año: 2010; p. 1 - 18

Plants are naturally exposed to a variety of environmental and physiological stress situations, such as the oxidative stress associated to growth and development. Soybeans require Fe as a nutrient, in a concentration higher than 10-8 M in solution, to meet their needs. Fe plays critical roles in biological processes, including photosynthesis, respiration and nitrogen assimilation. However, Fe has a dark side because it is toxic to the cell due to its capacity of being an active catalyst for the generation of reactive oxygen radical species that causes lipid peroxidation, DNA strand breaks, oxidation of proteins, and degradation of other biomolecules. Fe homeostasis is maintained by the coordinated regulation of its transport, utilization and storage. Fe traffic has to be strictly controlled, and ferritin is one of the main proteins involved. Moreover, ferritin can prevent Fe toxicity because of its ability to sequester several thousand of Fe atoms in their central cavity in a soluble, non-toxic bio-available form. However, anytime Fe uptake exceeds the metabolic needs of the cell and the storage capacity is overwhelmed, a low molecular weight Fe pool, referred to as the labile iron pool is increased. The Fe in this pool represents the catalytic active Fe, and its size needs to be closely restricted, mostly in chloroplasts and mitochondria since besides being important sites for Fe utilization, they also are specific places for free radical production through the electron transfer chains. The general aspects linked to oxidative metabolism in soybean embryonic axes both, under physiological and stress conditions, will be analyzed mostly in the early stages of growth. Fe function, its cellular distribution, and its participation in free radical reactions leading to cellular damage will be described and also analyzed under Fe overload condition. An integrative overview of these topics will provide information that could be the key to elaborate strategies to improve soybean development, and also human nutrition through bio-fortification strategies.