In 1997, the total cultivated area of GM crops was 1.7 million ha and increased gradually to reach 185.1 million ha in 26 countries in 2016 19 of these are developing countries beside 7 industrial countries. World cultivation of commercialized GM crops However, a conventionally bred variety with longer shelf-life prevented the product from becoming profitable. It was welcomed by consumers who purchased the fruit at high price. Calgene took the initiative to obtain the Food and Drug Administration (FDA) approval for its release in 1994. Tomato was the first commercially grown genetically modified whole food crop (called FlavrSavr) which was modified to ripen without softening by a Californian company, Calgene (Martineau 2001). In 1994, the European Union approved the commercial production of the plant as resistant to the herbicide bromoxynil (Martineau 2001). The first produced genetically modified plant in the laboratory was tobacco in 1983 and was tested in 1986 as herbicide-resistant in France and the USA. Recently, with the reached high technology, advanced techniques are carried out in laboratory to transfer genes that express the desired traits from a plant to a new plant (Martineau 2001). For example, a plant with a desired trait is selected and bred to produce more plants with such a trait. There are different methods to transfer genes to animals and plants where the old and most traditional one is through the selective breeding. When a gene from one organism is transferred to improve or induce desired change in another organism, in laboratory, the result is a genetically engineered (or modified) organism (which may also called transgenic organism). Others, however, are against Bt crops as they may cause risk to human. Some researchers support the cultivation of Bt crops depending upon the results of their laboratory and field studies on the safety of such crops. This review shows that there is a worldwide controversy about the safety of Bt crops to the environment and mammals. In 2016, the total world area cultivated with genetically modified crops (GM crops) reached about 185 million ha. Such Cry toxins are toxic to specific species of insects belongs to orders: Lepidoptera, Coleoptera, Hymenoptera, Diptera, and Nematoda. The crystal, referred to as Cry toxins, is proteins formed during sporulation of some Bt strains and aggregate to form crystals. Currently, the most common Bt crops are corn and cotton. In 1995, the Environmental Protection Agency (EPA) in USA approved the commercial production and distribution of the Bt crops: corn, cotton, potato, and tobacco. Bacillus thuringiensis ( Bt) crops are plants genetically engineered (modified) to contain the endospore (or crystal) toxins of the bacterium, Bt to be resistant to certain insect pests.
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