Golden Rice: An Example of Biotechnology in Agriculture

Rice is the staple food in the diet of many people in the world today, including many of those in Asia and Africa. Unfortunately, due to the process in which the rice is milled and made ready for consumption, it is lacking in some nutrients which are essential to good health. One of the nutrients that is missing from rice is Vitamin A. When a person's diet is made up primarily from rice, therefore, this can lead to that individual having a Vitamin A deficiency.

Vitamin A is needed for many functions of the human body, including reproduction, growth, vision and the immune system. As such, a diet which lacks this essential component can cause many long term health problems. These issues can include conditions such as night blindness, corneal ulcers, and other ocular problems, as well as fertility issues, and a diminished ability to fight off infection. Due to the prevalence of rice as a staple food across the globe, these issues are a very real risk for a large percentage of the world's population, especially those living in developing countries.

Scientists have been working for a long time for a solution to this global concern. To that end, they have developed two different strains of a plant called "Golden Rice". Golden rice is a strain of rice that has been genetically modified to help fight this kind of vitamin deficiency. Golden rice earned its name due to the golden yellow hue the rice takes on as a result of the addition of beta-carotene.

Beta-carotene is a precursor of Vitamin A and can safely be a primary part of the diet. It is impossible to overdose on it because of the body's natural regulation. This is unlike Vitamin A which can be toxic in high enough levels. The body stores beta-carotene and converts it to vitamin A only when needed. The endosperm of normal rice, the part that people consume, does not contain beta-carotene, though other parts of the rice plant do produce it. Golden rice has been genetically altered so that the endosperm now accumulates beta-carotene. This has been done using recombinant DNA technology.

Two beta-carotene biosynthesis genes were used to create the new golden strain of rice. These were psy, which comes from daffodils, and crt1, which comes from a soil bacterium called Erwinia uredovora. Lycopene cyclase was originally thought to be needed but as more experiments were conducted it turned out not to be required after all. Due to the process used and the use of an endosperm specific promoter, these are expressed only in the endosperm. The result is of course easily seen in the yellow color of the rice grains.

The combination of the two genes psy and crt1 should have produced lycopene, not beta-carotene. Lycopene remained unobserved in the golden rice, however. The exact reason why this was the case could initially not be determined satisfactorily. It has now been discovered, however, that apparently some of the rice plant's enzymes naturally process the lycopene into beta-carotene inside the endosperm. Were it not for the rice plant's natural enzymes, then, lycopene would be produced rather than the resultant beta-carotene.

The development of golden rice was originally begun in 1992, with a breakthrough coming in 1999, though the search for a viable golden rice can be traced back to 1982. It was created by Professor Ingo Potrykus from the Institute of Plant Sciences at the Swiss Federal Institute of Technology, and Professor Peter Beyer from the University of Freiburg. The details of the genetic alteration of the rice and the process of creating it were not published in Science until the year 2000 and this paper proved that the rice grain could produce beta-carotene to help supplement the diet. Before this time it was believed that this was an impossibility. Even Peter Beyer had his doubts about the success of the project at first. The strain was created with public funding and to aid in the prevention of vitamin A deficiency in poverty-stricken areas. Therefore, the people behind it took steps to ensure that the technology would be readily available to those who needed it.

To better help fight the vitamin deficiency that golden rice was created to combat, higher levels of beta-carotene per grain would be needed. A second variety of golden rice, dubbed Golden rice 2, was created by a biotechnology company in the private sector named Syngenta . This strain uses crt1 from the bacterium but combines it not with the original daffodil psy gene but instead a homologous gene from maize. The production of beta-carotene in golden rice 2 is 23 times as much as that in the original golden rice. Again, this beta-carotene enriched rice, created in 2005, will be available to any who wish to use it, as the private company has given out access to the technologies without cost.

As of this writing, however, almost nine years since the publication in Science of the details of Golden Rice, neither Golden Rice nor Golden Rice 2 are available for human purchase or consumption. This is partially due to the controversy surrounding it as a genetically modified crop, something which garners great opposition from varied sources, but also due to the large amount of testing required of said genetically altered crops. Genetically modified and engineered food crops must undergo many highly-detailed tests before they can be considered safe and ready for market. For instance, it is necessary to make certain that no new allergens have been created by the crossing of genes.

Ingo Potrykus remains a vocal champion of golden rice, insisting that modified food items have received an unearned bad reputation. Meanwhile, opponents of golden rice mention that there are perhaps better ways of supplementing the diet of those who are likely to suffer from a deficiency in vitamin A. As of right now, it is unknown when, and in fact if, golden rice will finally be allowed to be grown in the field.

Sources

Al-Balili, Salim and Beyer, Peter December 2005 Golden Rice - Five Years on the Road - Five Years to Go? TRENDS in Plant Science Vol. 10 Num. 12

Kryder D, Kowalsi SP, Krattiger AF. 2000. 'The Intellectual and Technical Property Components of pro-Vitamin A Rice (GoldenRice™): A Preliminary Freedom-To-Operate Review', ISAAA Briefs No 20. ISAAA: Ithaca, NY. 56 p.

Potrykus, Ingo "Golden Rice and Beyond" Plant Physiology March 2001, Vol. 125, pp. 1157-1161

Schaub, Patrick; Al-Balili, Salim; Drake, Rachel; Beyer, Peter April 2005 Biochemical Processes and Macromolecular Structures Why is Golden Rice Golden (Yellow) Instead of Red? Plant Physiology 138:441-450

Science. 2000 Jan 14;287(5451):241-3

Science. 2000 Jun 16;288(5473):1966-7

Sommer, Alfred, MD, MHS 2001 "Vitamin A Deficiency Disorders: Origins of the Problem and Approaches to Its Control"