Golden rice

Golden rice is a variety of Oryza sativa rice produced through genetic engineering to biosynthesize beta-carotene, a precursor of pro-vitamin A in the edible parts of rice.^[1] The scientific details of the rice were first published in Science in 2000.^[1] Golden rice was developed as a fortified food to be used in areas where there is a shortage of dietary vitamin A.^[2] In 2005 a new variety called Golden Rice 2 was announced which produces up to 23 times more beta-carotene than the original variety of golden rice.^[3] Neither variety is currently available for human consumption. Although golden rice was developed as a humanitarian tool, it has met with significant opposition from environmental and anti-globalization activists.^[4]

Creation

A simplified overview of the carotenoid biosynthesis pathway in golden rice. The enzymes expressed in the endosperm of golden rice, shown in red, catalyze the biosyntheis of beta-carotene from geranylgeranyl diphosphate. Beta-carotene is assumed to be converted to retinal and subsequently retinol (vitamin A) in the animal gut

Golden rice was created by Ingo Potrykus of the Institute of Plant Sciences at the Swiss Federal Institute of Technology, working with Peter Beyer of the University of Freiburg. The project started in 1992, and at the time of publication in 2000, golden rice was considered a significant breakthrough in biotechnology, as the researchers had engineered an entire biosynthetic pathway.

Golden rice was designed to produce beta-carotene, a precursor of vitamin A, in the part of rice that people eat, the endosperm. The rice plant can naturally produce beta-carotene, which is a carotenoid pigment that occurs in the leaves and is involved in photosynthesis. However, the plant does not normally produce the pigment in the endosperm, since photosynthesis does not occur in the endosperm.

Golden rice was created by transforming rice with two beta-carotene biosynthesis genes:

1. psy (phytoene synthase) from daffodil (Narcissus pseudonarcissus)
2. crt1 from the soil bacterium Erwinia uredovora

(The insertion of a lyc (lycopene cyclase) gene was thought to be needed, but further research showed it is already being produced in wild-type rice endosperm.)

The psy and crt1 genes were transformed into the rice nuclear genome and placed under the control of an endosperm-specific promoter, so they are only expressed in the endosperm. The exogenous lyc gene has a transit peptide sequence attached so it is targeted to the plastid, where geranylgeranyl diphosphate formation occurs. The bacterial crt1 gene was an important inclusion to complete the pathway, since it can catalyze multiple steps in the synthesis of carotenoids, while these steps require more than one enzyme in plants.^[5] The end product of the engineered pathway is lycopene, but if the plant accumulated lycopene, the rice would be red. Recent analysis has shown the plant's endogenous enzymes process the lycopene to beta-carotene in the endosperm, giving the rice the distinctive yellow colour for which it is named.^[6] The original golden rice was called SGR1, and under greenhouse conditions it produced 1.6 µg/g of carotenoids.

Subsequent development

Golden rice has been bred with local rice cultivars in the Philippines, Taiwan and with the American rice cultivar 'Cocodrie'.^[7] The first field trials of these golden rice cultivars were conducted by Louisiana State University Agricultural Center in 2004.^[7] Field testing will allow a more accurate measurement of the nutritional value of golden rice, and will enable feeding tests to be performed. Preliminary results from the field tests have shown field-grown golden rice produces 4 to 5 times more beta-carotene than golden rice grown under greenhouse conditions.^[8]

In 2005, a team of researchers at biotechnology company, Syngenta, produced a variety of golden rice called "Golden Rice 2". They combined the phytoene synthase gene from maize with crt1 from the original golden rice. Golden rice 2 produces 23 times more carotenoids than golden rice (up to 37 µg/g), and preferentially accumulates beta-carotene (up to 31 µg/g of the 37 µg/g of carotenoids).^[3] To receive the Recommended Dietary Allowance (RDA), it is estimated that 144 g of the most high-yielding strain would have to be eaten. Bioavailability of the carotene from either variety has not been tested in any model.^[9]

In June 2005, researcher Peter Beyer received funding from the Bill and Melinda Gates Foundation to further improve golden rice by increasing the levels of or the bioavailability of pro-vitamin A, vitamin E, iron, and zinc, and to improve protein quality through genetic modification.^[10]

A 2010 article forecast that golden rice would clear final regulatory hurdles and reach the market in 2012.^[11]

Potential use to combat vitamin A deficiency

Prevalence of vitamin A deficiency. Red is most severe (clinical), green least severe. Countries not reporting data are coded blue. Source: WHO

The research that led to golden rice was conducted with the goal of helping children who suffer from vitamin A deficiency (VAD). At the beginning of the 21st century, 124 million people, in 118 countries in Africa and South East Asia, were estimated to be affected by VAD. VAD is responsible for 1–2 million deaths, 500,000 cases of irreversible blindness and millions of cases of xerophthalmia annually.^[12] Children and pregnant women are at highest risk. Vitamin A is supplemented orally and by injection in areas where the diet is deficient in vitamin A. As of 1999, there were 43 countries that had vitamin A supplementation programs for children under 5; in 10 of these countries, two high dose supplements are available per year, which, according to UNICEF, could effectively eliminate VAD.^[13] However, UNICEF and a number of NGOs involved in supplementation note more frequent low-dose supplementation should be a goal where feasible.^[14]

Because many children in countries where there is a dietary deficiency in vitamin A rely on rice as a staple food, the genetic modification to make rice produce provitamin A (beta-carotene) is seen as a simple and less expensive alternative to vitamin supplements or an increase in the consumption of green vegetables or animal products. It can be considered as the genetically engineered equivalent of fluoridated water or iodized salt.

Initial analyses of the potential nutritional benefits of golden rice suggested consumption of golden rice would not eliminate the problems of blindness and increased mortality, but should be seen as a complement to other methods of vitamin A supplementation^[15][16]. Since then, improved strains of golden rice have been developed containing sufficient provitamin A to provide the entire dietary requirement of this nutrient to people who eat about 75g of golden rice per day.^[3]

In particular, since carotenes are hydrophobic, there needs to be a sufficient amount of fat present in the diet for golden rice (or most other vitamin A supplements) to be able to alleviate vitamin A deficiency. In that respect, it is significant that vitamin A deficiency is rarely an isolated phenomenon, but usually coupled to a general lack of a balanced diet (see also Vandana Shiva's arguments below). Hence, assuming a bioavailability on par with other natural sources of provitamin A, Greenpeace estimated adult humans would need to eat about 9 kilograms of cooked golden rice of the first breed to receive their RDA of beta-carotene, while a breast-feeding woman would need twice the amount; the effects of an unbalanced (fat-deficient) diet were not fully accounted for. In other words, it would probably have been both physically impossible to grow enough as well as to eat enough of the original golden rice to alleviate debilitating vitamin A deficiency.^[17] This claim however referred to a prototype cultivar of golden rice; more recent versions have considerably higher quantities of vitamin A in them.^[18]

Intellectual property issues

Golden rice and co-creator Professor Ingo Potrykus on the cover of TIME magazine, 7 August 2000

Potrykus has spearheaded an effort to have golden rice distributed for free to subsistence farmers. This required several companies which had intellectual property rights to the results of Beyer's research to license it for free. Beyer had received funding from the European Commissions 'Carotene Plus' research program, and by accepting those funds, he was required by law to give the rights to his discovery to the corporate sponsors of that program, Zeneca (now Syngenta). Beyer and Potrykus made use of 70 intellectual property rights belonging to 32 different companies and universities in the making of golden rice. They needed to establish free licences for all of these, so Syngenta and humanitarian partners in the project could use golden rice in breeding programs and to develop new crops.^[19]

Free licenses, so called Humanitarian Use Licenses, were granted quickly due to the positive publicity that golden rice received, particularly in TIME magazine in July 2000. Golden rice was said to be the first genetically modified crop that was inarguably beneficial, and thus met with widespread approval. Monsanto Company was one of the first companies to grant the group free licences.^[20]

The group also had to define the cutoff between humanitarian and commercial use. This figure was set at US$10,000. Therefore, as long as a farmer or subsequent user of golden rice genetics does not make more than $10,000 per year, no royalties need be paid to Syngenta for commercial use. There is no fee for the humanitarian use of golden rice, and farmers are permitted to keep and replant seed.

Opposition

Critics of genetically engineered crops have raised various concerns. One of these is that golden rice originally did not have sufficient vitamin A. This problem was solved by the development of new strains of rice.^[3] However, there are still doubts about the speed at which vitamin A degrades once the plant is harvested, and how much would remain after cooking.^[21] A 2009 study of boiled golden rice fed to volunteers concluded that Golden Rice is effectively converted into vitamin A in humans^[22]

Greenpeace opposes the release of any genetically modified organisms into the environment, and is concerned that golden rice is a Trojan horse that will open the door to more widespread use of GMOs.^[23]

Vandana Shiva, an Indian anti-GMO activist, argued the problem was not that the crop had any particular deficiencies, but that there were potential problems with poverty and loss of biodiversity in food crops. These problems are aggravated by the corporate control of agriculture based on genetically modified foods. By focusing on a narrow problem (vitamin A deficiency), Shiva argued, the golden rice proponents were obscuring the larger issue of a lack of broad availability of diverse and nutritionally adequate sources of food.^[24] Other groups have argued a varied diet containing foods rich in vitamin A such as sweet potato, leafy green vegetables and fruit would provide children with sufficient vitamin A.^[25]

Because of lacking real-world studies and uncertainty about how many people will use golden rice, WHO malnutrition expert Francesco Branca concludes "giving out supplements, fortifying existing foods with vitamin A, and teaching people to grow carrots or certain leafy vegetables are, for now, more promising ways to fight the problem"^[26].

References

External links

• Golden Rice Project
• Grains of delusion: golden rice seen from the ground: joint report by Biothai (Thailand), Cedac (Cambodia), DRCSC (India), Grain, Masipag (Philippines), Pan-Indonesia and Ubinig (Bangladesh)

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