White rice and golden rice

Creation of golden rice

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 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 1.6 µg/g of carotenoids.

Subsequent development

Golden rice has been bred with local rice cultivars in the Philippines, Taiwan and with the American rice variety Cocodrie. The first field trials of these golden rice cultivars were conducted by Louisiana State University Agricultural Center 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 4 to 5 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 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 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

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

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

Golden rice and co-creator Professor Ingo Potrykus on the cover of TIME magazine, 2000-08-07

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 have raised various concerns. One of these is that golden rice oringally did not have sufficient vitamin A, but new strains were developed that solve this problem.

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] 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 contend that a varied diet is beyond the means of many of the poor, which they say is why they subsist on a diet mainly 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.

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

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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