According to the World Health Organization, approximately two billion people suffer from iron deficiency. They tire easily, experience problems in metabolizing harmful substances in their bodies and eventually suffer from anemia.
Women and children are particularly affected in developing countries, where rice is the major staple food. Peeled rice, also called polished rice, does not have enough iron to satisfy the daily requirement, even if consumed in large quantities. For many people, a balanced diet or iron supplements are often unaffordable.
Rice actually has a lot of iron, but only in the seed coat. Because unpeeled rice quickly becomes rancid in tropical and subtropical climates, however, the seed coat - along with the precious iron - has to be removed for storage. Researchers working with Christof Sautter and Wilhelm Gruissem in the laboratory of plant biotechnology at ETH Zurich have now succeeded in increasing the iron content in polished rice by transferring two plant genes into an existing rice variety. Their work was published today in the online edition of "Plant Biotechnology Journal".
The rice plants express the two genes to produce the enzyme nicotianamin syn-thase, which mobilizes iron, and the protein ferritin, which stores iron. Their synergistic action allows the rice plant to absorb more iron from the soil and store it in the rice kernel. The product of nicotianamine synthase, called nicotianamin, binds the iron temporarily and facilitates its transportation in the plant. Ferritin acts as a storage depot for iron in both plants and humans. The researchers controlled the genes introduced in such a way that nicotianamin synthase is expressed throughout the rice plant, but ferritin only in the rice kernel. Together, the expression of the genes has a positive impact on iron accumulation in the rice kernel and increases the iron content more than six-fold compared to the original variety.