Development of iron-rich rice and improvement of its absorption in humans by genetic engineering

Rice, the major food staple for most people in Southeast Asia, is characterised by a very low content of iron. Furthermore, its absorption in human is also very poor. Iron deficiency is still the most prevalent micronutrient deficiency world-wide and it has been estimated that about 1.3 billion of the world's 5.7 billion inhabitants suffer from nutritional iron deficiency anaemia. Here we present approaches that aim to increase the iron content of the rice endosperm (Oryza sativa) and to improve its absorption in the human intestine. The experimental strategy is to transfer genes for iron improvement into rice by means of genetic engineering. To increase the iron content in the endosperm we first introduced a ferritin gene from Phaseolus vulgaris into rice. In addition, two attempts to improve the iron absorption in the human intestine have been adopted. First, the level of the main inhibitor of iron absorption, the phytic acid, will be decreased in the diet with a heat-tolerant phytase from Aspergillus fumigatus. Second, as cysteine peptides are considered a major enhancer of iron absorption, we overexpressed the endogenous cysteine-rich metallothionein-like protein. In this way the daily iron intake and absorption could be improved in populations where rice is the staple food.