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Golden Rice - I. Potrykus

Federal Institute of Technology (ETH), Zurich, Switzerland


Malnutrition disorders are the cause of 24 000 deaths a day. “Golden Rice” represents a genetic engineering concept for the development of nutrient-dense staple crops which can make an important contribution to the reduction of malnutrition in developing countries. Major micronutrient deficiency disorders concern protein, energy, iron, zinc, vitamin A and iodine. These deficiencies are especially severe in countries where rice is the major staple. Traditional interventions - such as distribution, fortification, dietary diversification and measures against infectious diseases - are very helpful in reducing deficiency disorders, but they have not solved (and probably cannot solve) the problem. Statistics demonstrate that, despite the efforts made to apply these traditional interventions, every year there are 2.4 billion women and children suffering from iron deficiency, and 400 million children suffering from vitamin A deficiency. Nutrient-dense staple crops represent an opportunity to complement traditional interventions in a sustainable manner; and genetic engineering has the potential to substantially enhance breeding for nutrient-dense staple crop varieties.


Protein deficiency

Protein deficiency relates to both quantity and quality (the content of essential amino acids) of dietary protein. Rice is rich in carbohydrates (energy), but low in protein, vitamins and minerals, and a typical daily diet of 300 g provides only 10 percent of the requirement of essential amino acids. Genetic engineering to create an ideal balanced mixture of the ten missing essential amino acids (isoleucine, leucine, lysine, methyonine, cysteine, phenylalanine, tyrosine, threonine, tryptophane and valine) is beyond the capacity of currently available technologies. However, Asp-1, a synthetic gene developed by Jesse Jaynes, and coding for an ideal high-quality storage protein (providing a balanced mixture of all ten essential amino acids) offered the solution. In order to verify whether the rice endosperm could provide the biochemical background required to assemble such a protein and to obtain information required, the Asp-1 gene was placed under endosperm-specific control, linked to an appropriate target sequence for import into the endosperm protein storage vesicles and transformed into rice (japonica TP309). The Asp-1 transgenic rice plants recovered and, on the basis of Western data, it can be concluded that they accumulate the Asp-1 protein in their endosperm in varying concentrations and thus provide a mixture of the essential amino acids required. Detailed biochemical analysis must verify this preliminary assumption and check whether the concentrations obtained are nutritionally relevant.

Iron deficiency

Iron deficiency resulting from a rice diet is the consequence of:

The genetic engineering task for the endosperm was, therefore to:

Transgenic ferritin (from Phaseolus vulgaris) has so far increased iron content twofold; a transgenic metallothionin (from Oryza sativa) led to a sevenfold increase in an iron resorption-enhancing cystein-rich protein; and transgene coding for a heat-stable phytase

(from Aspergillus fumigatus) produced high inhibitor-degrading phytase activity, which to date has not maintained its heat-stability character. (Lucca et al., 2001). Given that phytate degradation after cooking is essential (to leave the phytate required for germination untouched), alternative strategies are being elaborated and further phytate experiments are in progress.

Vitamin A deficiency

Vitamin A deficiency in rice-consuming populations arises from the fact that milled rice is totally devoid of provitamin A and that poverty prevents a diversified diet. The situation is especially severe when children are raised on rice gruel. The addition of provitamin A to rice endosperm requires the engineering of a complete biochemical pathway - a task initially considered impossible. The goal was finally achieved thanks to:

The introduction of transgenes for phytoene synthase (Narcissus), a phytoene/x-carotene double-desaturase (Erwinia) and lycopene cyclase (Narcissus) completed the biochemical pathway leading from the latest available precursor geranyl-geranly-pyrrhophosphate to b-carotene (provitamin A). Biochemical analysis of the polished rice kernels confirmed that the “golden” colour of the endosperm was due to varying amounts of provitamin A and further terpenoids of dietary interest (such as lutein and zeaxanthin). (Ye et al., 2000). A concentration of 1.6 g/g (according to the calculation of an experienced vitamin A nutritionalist, Prof. Robert Russell, Boston) may be sufficient to prevent vitamin-A-deficiency disorders in a daily diet of 200 g of Golden Rice. The hypothesis is to be tested with nutritional studies using human volunteers; conclusive data, however, will not be available before 2004.

For any “normal” scientist, such success would represent the completion of their work. For scientists motivated to contribute to the reduction of malnutrition in developing countries, this was only the beginning of a series of challenges.


The Golden Rice project is a humanitarian project designed to help poor people in developing countries. In order to relieve the malnutrition suffered by poor populations in developing countries, the new technology must be passed on to subsistence farmers and the urban poor free of charge and without limitations; it was therefore important to use public funding only. Nevertheless, the basic genetic engineering technology used to develop provitamin A rice also used a large number of patented technologies. “Freedom to operate for humanitarian use” - the necessary basis for variety development by partner institutions in developing countries - was therefore applied and an alliance was formed with the ag-biotech industry, based on an agreement which transfers the rights for commercial exploitation to the ag-biotech industry, which in turn supports the humanitarian project. In order to comply with the definition of “humanitarian”, the project aimed to assist where: “income from Golden Rice per farmer or trader in developing countries [was] below US$10 000 per annum” - a definition which safely included the target population. The technology is now available (via free licences) to public research institutions for breeding, variety development and de-novo transformation. Transfer of the technology requires a sub-sub-licence agreement with the inventors (as opposed to with the ag-biotech industry). To date, such agreements have been signed with: IRRI (01) and PhilRice (02) (Philippines); Cuu Long Delta Rice Research Institute (03) (Viet Nam); Department of Biotechnology, Delhi (04), DRR, Hyderabad (05), IARI, New Delhi (06), UDSC, New Delhi (07) and TNAU, Tamil Nadu (08) (India); Institute of Genetics, Academia Sinica, Beijing (09) and National Key Laboratory of Crop Genetic Improvement, Wuhan (10) (China); Agency for Agricultural Research and Development, Jakarta (11) (Indonesia); and DSIR, Brumeria, Pretoria (12) (South Africa). The above institutions constitute the growing International Humanitarian Golden Rice Network.


To ensure proper handling of the GMO (genetically modified organism) material, a “Humanitarian Board” was established to: supervise the choice of partners; support further improvement; oversee needs, availability, biosafety and socio-economic assessments; coordinate activities in the different countries; support fund-raising from public resources; support deregulation; facilitate exchange of information; and mediate information and general support for the humanitarian project. Members of the Board include: G. Toenniessen (Rockefeller Foundation), A. Dubock (Syngenta), W. Padolina (IRRI), R.M. Russell (USDA), H.E. Bouis (IFPRI), G. Khush (IRRI), K. Jenny (Indo-Swiss Collaboration in Biotechnology), A. Kratticker (Cornell University) and the inventors P. Beyer and I. Potrykus (Chairmen). Variety development in the partner institutions takes place either through backcrossing into popular local varieties or via direct transformation. Backcrossing from the experimental japonica rice line into the essential indica rice lines requires approximately eight generations (or 3 years). Direct transformation may be faster and has already been achieved in a series of indica varieties (including the very popular IR 64) by the Vietnamese and Philippine partner institutions.


Golden Rice has become a point of dispute between proponents and opponents of plant biotechnology in food production. Radical GMO opposition is a major constraint and has the potential to prevent the poor in developing countries from benefiting from the project. Greenpeace and numerous other NGOs (non-government organizations) are determined to prevent the development and use of Golden Rice: it is seen as a “Trojan Horse”, opening the road for GMO technology in developing countries. At present, the opposition’s arguments all fail: Golden Rice benefits the poor, not industry; it has been developed in the public domain, not by industry; it will be available for the poor free of charge and without limitations; subsistence farmers can use part of their harvest for subsequent sowings; cultivation does not require additional inputs; there are no real risks for the environment. Furthermore, the public and the media understand the moral dimension of the project and the opposition is therefore in a difficult situation; it is trying to bypass this moral dilemma by claiming that children have to eat 3.75 kg/day of Golden Rice, a condition which would make its widespread adoption unfeasible. Unfortunately, data to prove that 200 g/day are probably sufficient will not be available until early 2004.


It is widely accepted that food derived from transgenic plants must successfully pass all requirements set up by regulatory authorities. However, the existing regulatory framework may severely delay - or even prevent - the use of Golden Rice for the reduction of diseases resulting from malnutrition in the poor populations of developing countries. The regulatory framework has become so extensive and the requirements so sophisticated that the required financial input alone is unrealistic for a “humanitarian” project. Another important limitation is the time factor: Golden Rice has been a reality since February 1999. Since the spring of 2002 the trait has been available in IR 64, a popular indica rice variety grown in many developing countries. New experimental adjustments are, however, required in order that Golden Rice may comply with the regulatory procedure. These factors result in exploitation of the technology being delayed for many years. At stake are not the sensitivities of well-fed European consumers, but the lives and health of large populations who depend upon a sustainable reduction in malnutrition (the cause of 24 000 deaths a day). It must therefore be asked what level of sophistication in regulation is scientifically and morally justified, and to what extent regulation is merely the consequence of politicians giving in to the pressure of activists who operate successfully on an emotional level. The Golden Rice Humanitarian Board is determined to carry out the humanitarian project at the highest regulatory levels, but the question nevertheless remains: is it justified to delay the use of a technology for years because of unconfirmed risks, if the consequence is thousands of deaths and severe health problems (e.g. irreversible blindness) in people who could otherwise live a healthy and productive life? What is more important to our society: a regulatory framework for minor and mostly hypothetical risks or the life and health of underprivileged human beings? Deregulation should balance the risks and benefits. The time has come to reevaluate the regulatory framework (at least in the context of humanitarian projects) in order to identify what is essential and what is merely a response to political pressure.

One plant most probably now contains nine transgenes to combine provitamin A, high iron content, high quality protein content and insect resistance. According to experts in regulatory affairs, deregulation for this transgenic plant is impossible - it will be problematic enough obtaining deregulation for provitamin A rice alone, because the principle of “substantial equivalence” does not apply. Do we really want to ignore the solutions genetic engineering can provide for malnutrition in developing countries because of the sensitivities of a well-fed European minority?


Lucca, P., Hurrell, R. & Potrykus, I. 2001. Genetic engineering approaches to improve the bioavailability and the level of iron in rice grains. Theor. Appl. Genetics, 102: 392-397.

Ye, X., Al-Babili, S., Kloeti, A., Zhang, J., Lucca, P., Beyer, P. & Potrykus, I. 2000. Engineering provitamin A (b-carotene) biosynthetic pathway into (carotenoid-free) rice endosperm. Science, 287: 303-305.

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