More iron in polished rice

A glimmer of hope in the fight against iron deficiency in Asia

Genetically modified rice plants © ETH Zurich
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Husked rice does not contain enough iron to meet the daily needs of humans. Now scientists have succeeded in increasing the iron content in polished rice grains sixfold. The researchers transferred two plant genes into an existing rice variety. In the future, the plants will alleviate iron deficiency, especially in African and Asian developing countries.

According to the World Health Organization, around two billion people suffer from iron deficiency. These people tire quickly, can only inadequately reduce pollutants in the body and become ill over an extended period of anemia. Particularly affected are women and children in developing countries, who mainly feed on rice. Because the husked rice grains of polished rice do not contain enough iron and do not even cover the daily requirement of a person, even with high consumption. A balanced diet or iron supplements are unaffordable to many people in these countries.

The rice is actually a lot of iron - but only in the husk of rice grain. However, since paddy rice quickly becomes rancid in tropical and subtropical climates, it is necessary to remove the rice hull together with the valuable iron for storage. Scientists led by Christof Sautter and Professor Wilhelm Gruissem in the Laboratory of Plant Biotechnology at ETH Zurich have now succeeded in increasing the iron content in husked rice grains sixfold. Their work is presented in the current online edition of the "Plant Biotechnology Journal".

Genes mobilize and store iron

The rice plant uses the introduced genes to produce more and more of the enzyme nicotianamine synthase, which mobilizes the iron, and the protein ferritin, which stores the iron. Their interaction ensures that the rice plant absorb more iron from the soil and can accumulate and store this iron in the rice grain. The product of nicotianamine synthase, the

Nicotianamine temporarily binds the iron mobilized from the soil and makes the iron transportable in the plant. display

Ferritin is a depot for iron in the plant as well as in humans. The researchers have controlled the activity of the inserted genes so that nicotianamine synthase is formed in the whole rice plant, but the ferritin only in the interior of the rice grain. Thus, the interaction of the two genes has a positive effect on the iron content of the husked rice grain and increases it in the polished grain up to six times compared to the original rice variety.

No negative effects expected

The ETH scientists expect a lot from the new rice variety. The prototypes in the greenhouse are externally indistinguishable from normal plants and give no indication of possible disadvantages such as crop losses. "Next we have to test in field experiments, if the rice plants can also exist under agricultural conditions, " says Gruissem. The ETH Zurich researcher sees no danger that genetically modified plants could have a negative impact on their environment. It is unlikely that the rice plants will leach the soil due to improved iron absorption, because iron is the most common metallic element in the soil.

From agricultural cultivation still years away

However, before the ferrous rice can be cultivated, the researchers in the greenhouse and in the open field must carry out many biosafety investigations and agronomic tests. Until then, the prototypes are not suitable for agricultural cultivation. Although the new rice variety already contains levels of iron that are physiologically effective in nutrition, Gruissem wants to further increase the iron content in the rice grains. Because many people who suffer from iron deficiency can only afford one meal a day. If the scientists succeeded in increasing the iron in the rice grain ten to twelve times, a rice meal would already be sufficient to cover the daily iron needs of a human being.

The experiences with the "Golden Rice" containing vitamin A, which are being studied at ETH Zurich and the University of Freiburg i.Br. showed that it takes years to genuinely grow rice. The regulatory burden and cost are high to provide genetically modified crops for agriculture and consumers. The goal of the ETH scientists is to make the genetically modified rice available to small farmers and self-sufficient farmers free of charge.

(Swiss Federal Institute of Technology Z rich (ETH Zurich), 21.07.2009 - NPO)