Genetically modified rice are rice strains that have been genetically modified (also called genetic engineering). Rice plants have been modified to increase micronutrients such as vitamin A, accelerate photosynthesis, tolerate herbicides, resist pests, increase grain size, generate nutrients, flavors or produce human proteins. The natural movement of genes across species, often called horizontal gene transfer or lateral gene transfer, can also occur with rice through gene transfer mediated by natural vectors. Transgenic events between rice and Setaria millet have been identified. The cultivation and use of genetically modified varieties of rice remains controversial and is not approved in some countries.
History In 2000, the first two GM rice varieties both with herbicide-resistance, called LLRice60 and LLRice62, were approved in the United States. Later, these and other types of herbicide-resistant GM rice were approved in Canada, Australia, Mexico and Colombia. However, none of these approvals triggered commercialization. Reuters reported in 2009 that China had granted biosafety approval to GM rice with pest resistance, but that strain was not commercialized. As of December 2012 GM rice was not widely available for production or consumption. Research suggests that since rice is a staple crop across the world, improvements have potential to alleviate hunger, malnutrition and poverty. In 2018, Canada and the United States approved genetically modified golden rice for cultivation, with Health Canada and the US Food and Drug Administration declaring it safe for consumption. As of 2021, salt-tolerant "seawater" rice in China had been planted on 400,000 ha (990,000 acres) in soils with up to 4 grams of salt per kilogram, with yields averaging 8.8 tons per hectare, according to Qingdao Saline-Alkali Tolerant Rice Research and Development Center.
Traits
Herbicide resistance In 2000–2001 Monsanto researched adding glyphosate tolerance to rice but did not attempt to bring a variety to market. Bayer's line of herbicide resistant rice is known as LibertyLink. LibertyLink rice is resistant to glufosinate (the active chemical in Liberty herbicide). Bayer CropScience is attempting to get their latest variety (LL62) approved for use in the EU. The strain is approved for use in the US but is not in large-scale use. Clearfield rice was bred by selection from variations created in environments known to cause accelerated rates of mutations. This variety tolerates imidazole herbicides. It was bred by traditional breeding techniques that are not considered to be genetic engineering. Clearfield is also crossbred with higher yielding varieties to produce an overall hardier plant.
Nutritional value
Golden rice with higher concentrations of Vitamin A was originally created by Ingo Potrykus and his team. This genetically modified rice is capable of producing beta-carotene in the endosperm (grain) which is a precursor for vitamin A. Syngenta was involved in the early development of Golden Rice and held some intellectual property that it donated to non-profit groups including the International Rice Research Institute (IRRI) to develop on a non-profit basis. The scientific details of the rice were first published in Science Magazine in 2000.
The World Health Organization stated that iron deficiency affects 30% of the world's population. Research scientists from the Australian Centre for Plant Functional Genomics (ACPFG) and IRRI to are working to increase the amount of iron in rice. They have modified three populations of rice by over expressing the genes OsNAS1, OsNAS2 or OsNAS3. The research team found that nicotianamine, iron, and zinc concentration levels increased in all three populations relative to controls.
Pest resistance
Bt rice BT rice is modified to express the cryIA(b) gene of the Bacillus thuringiensis bacterium. The gene confers resistance to a variety of pests including the rice borer through the production of endotoxins. The Chinese Government is doing field trials on insect resistant cultivars. The benefit of BT rice is that farmers do not need to spray their crops with pesticides to control fungal, viral, or bacterial pathogens. Conventional rice is sprayed three to four times per growing season to control pests. Other benefits include increased yield and revenue from crop cultivation. China approved the rice for large-scale use as of 2009. Resistance management is needed in southeast Asia to prevent loss of efficacy of Bt in rice.
Allergy resistance Researchers in Japan are attempting to develop hypoallergenic rice cultivars. Researchers are trying to repress the formation of allergen AS-Albumin. Japanese researchers tested genetically modified rice on macaque monkeys that would prevent allergies to cedar pollen, which causes hay fever. Cedar allergy symptoms include itchy eyes, sneezing and other serious allergic reactions. The modified rice contains seven proteins from cedar pollen (7Crp) to block these symptoms by inducing oral tolerance. Takaiwa is conducting human clinical trials with this 7Crp protein as an oral vaccine.
C4 photosynthesis In 2015 a consortium of 12 laboratories in eight countries developed a cultivar that displayed a rudimentary form of C4 photosynthesis (C4P) to boost growth by capturing carbon dioxide and concentrated it in specialized leaf cells. C4P is the reason corn and sugarcane grow so rapidly. Engineering C4 photosynthesis into rice could increase yields per hectare by roughly 50 percent. The current cultivar still relies primarily on C3 photosynthesis. To get them to completely adopt C4P, the plants must produce specialized cells in a precise arrangement: one set of cells to capture the carbon dioxide and to surround other cells that concentrate it. Some (possibly dozens of) genes involved in producing these cells remain to be identified. Other C3P crops that could exploit such knowledge include wheat, potatoes, tomatoes, apples and soybeans.
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