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Golden rice



  Golden rice is a variety of rice (Oryza sativa) produced through genetic engineering to biosynthesize the precursors of beta-carotene (pro-vitamin A) in the edible parts of rice. 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.

Additional recommended knowledge

Contents

Creation of golden rice

 

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 that 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 that they are only expressed in the endosperm. The exogenous lyc gene has a transit peptide sequence attached so that 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.[4] The end product of the engineered pathway is lycopene, but if the plant accumulated lycopene the rice would be red. Recent analysis has shown that 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.[5] The original Golden rice was called SGR1, and under greenhouse conditions it produced 1.6µg/g of carotenoids.

Subsequent development

Golden rice has been bred with local rice cultivars in the Philippines, Taiwan and with the American rice variety Cocodrie. The first field trials of these golden rice cultivars were conducted by Louisiana State University AgCenter in 2004.[6] 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 that field grown Golden rice produces 3 to 4 times more beta-carotene than Golden rice grown under greenhouse conditions.[7]

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 37µg/g), and preferentially accumulates beta-carotene (up to 31µg/g of the 37µg/g of carotenoids).[3] To receive the Recommended Dietary Allowance (RDA), it is estimated that 144 g of this rice would have to be eaten. Bioavailiability of the carotene from either variety has not been tested in any model.[8]

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.[9]

Golden rice and vitamin A deficiency

  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.[10] 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.[11] However UNICEF and a number of NGOs involved in supplementation note that more frequent low-dose supplementation should be a goal where feasible.[12]

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.

Theoretical analyses of the potential nutritional benefits of golden rice show that 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.[13]

Golden rice and intellectual property issues

  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 that Syngenta and humanitarian partners in the project could use golden rice in breeding programs and to develop new crops.[14]

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 was one of the first companies to grant the group free licences.

The group also had to define the cutoff between humanitarian and commercial use. This figure was set at USD$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. At present, Syngenta has no interest in commercial use of the plant.

Opposition

Critics of genetically engineered crops, such as Greenpeace, raised various concerns. Originally, golden rice did not have sufficient vitamin A, but new strains were developed that solve this problem. However, Greenpeace opposes all genetically modified organisms, and is concerned that golden rice is a Trojan horse that will open the door to more widespread use of GMOs.[15]

Vandana Shiva, an Indian anti-GMO activist, argued that the problem was not particular deficiencies in the crops themselves, but 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.[16] Similarly other groups have argued that a varied diet containing vitamin A rich foods like sweet potato, leafy green vegetables and fruit would provide children with sufficient vitamin A.[17] While this is true, others also contend that a varied diet is beyond the means of many of the poor, which they say is why they subsist on a diet of rice. The poorest people may not have an option to eat a varied diet, necessarily relying on one or few foods to provide complete nutrition. Opponents of genetically modified foods, however, have yet to propose or act upon a viable solution to the problem of malnutrition. The work at ECHO may be a good step towards such solutions, as they support development workers by providing healthy, albeit non-standard food crops and related knowledge to poor (semi)tropical regions of the world.

The aleurone layer that surrounds the rice endosperm is removed by a process called milling or polishing in most countries, to improve the shelf life of the rice. Brown rice with the aleurone intact contains more B vitamins, iron, manganese, selenium, zinc and phosphorus than milled rice. The Institute of Science in Society claims that if rice was not milled that supplementation would not be necessary.[18] However USDA data shows that brown rice does not contain any more beta carotene than milled rice.[19][20] Scientists at the International Rice Research Institute are screening rice germplasm, and trying conventional breeding approaches for breeding varieties with increased beta carotene in the aleurone.[21]

References

  1. ^ Ye et al. 2000. Engineering the provitamin A (beta-carotene) biosynthetic pathway into (carotenoid-free) rice endosperm. Science 287 (5451): 303-305 PMID 10634784
  2. ^ One existing crop, genetically engineered "golden rice" that produces vitamin A, already holds enormous promise for reducing blindness and dwarfism that result from a vitamin-A deficient diet. - Bill Frist, physician and politician, in a Washington Times commentary - November 21, 2006 [1]
  3. ^ a b Paine et al. 2005. Improving the nutritional value of Golden Rice through increased pro-vitamin A content. Nature Biotechnology doi:10.1038/nbt1082
  4. ^ Hirschberg, J. 2001. Carotenoid biosynthesis in flowering plants. Current Opinion in Plant Biology 4:210-218
  5. ^ Schaub, P. et al. 2005. Why Is Golden Rice Golden (Yellow) Instead of Red?. Plant Physiology 138:441–450
  6. ^ LSU AgCenter Communications. ‘Golden Rice’ Could Help Reduce Malnutrition, 2004
  7. ^ Goldenrice.org [2]
  8. ^ Datta, S.K. et al. 2007. Golden rice: introgression, breeding, and field evaluation. Euphytica. 154 (3): 271-278
  9. ^ Grand Challenges in Global Health, Press release, June 27, 2005
  10. ^ Humphrey, J.H., West, K.P. Jr, and Sommer, A. 1992. Vitamin A deficiency and attributable mortality in under-5-year-olds. WHO Bulletin 70: 225-232
  11. ^ UNICEF. Vitamin A deficiency
  12. ^ Vitamin A Global Initiative. 1997. A Strategy for Acceleration of Progress in Combating Vitamin A Deficiency
  13. ^ Dawe, D., Robertson, R. and Unnevehr, L. 2002. Golden rice: what role could it play in alleviation of vitamin A deficiency? Food Policy 27:541-560
  14. ^ Potrykus, I. 2001. Golden Rice and Beyond. Plant Physiology 125:1157-1161
  15. ^ Greenpeace. 2005. All that Glitters is not Gold: The False Hope of Golden Rice
  16. ^ Shiva, V. The Golden Rice Hoax
  17. ^ Friends of the Earth. Golden Rice and Vitamin A Deficiency
  18. ^ Institute of Science in Society. The 'Golden Rice' - An Exercise in How Not to Do Science
  19. ^ USDA National Nutrient Database for Standard Reference. Rice, brown, long-grain, cooked
  20. ^ USDA National Nutrient Database for Standard Reference. Rice, white, long-grain, regular, cooked
  21. ^ International Rice Research Institute. 2005. Program 3, Annual Report of the Director General 2004-05
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Golden_rice". A list of authors is available in Wikipedia.
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