Jonathan O’Sullivan - 42899268
Due to the high demand for an increased food supply and better food quality throughout the world, an alternative food source, Genetically Modified (GM) Food or transgenic food, has been developed. GM foods are made by inserting genes of other species into plant genomes (Kartha, 2010). GM plants have additional advantages such as having a greater tolerance to environmental stresses, having a better taste, looking more aesthetically pleasing, having increased shelf life or increased nutritional value, such as Golden Rice (Kartha, 2010; Villano, 2000). The GM food, Golden Rice is biofortified with β-carotene, a precursor of Vitamin A. This nutrient-enhanced strain of rice offers people in developing countries a valuable and affordable choice in the fight against malnutrition and Vitamin A deficiency (Mayer, 2005; Welch, 2004)(See Figure 1).
Figure 1: Example of fully grown Golden Rice in a field
According to the World Health Organization, dietary vitamin A deficiency causes 250,000 to 500,000 children in developing countries to become visually impaired each year (Reece, et al, 2012; Welch, 2004; Mayer, 2005). More than half the children who lose their sight die within a year of becoming blind. Vitamin A deficiency also compromises the immune system, increasing disease and infection susceptibility in children and thus increasing the mortality rate (Graham, 2010; Welch, 2004). The genetically modified Golden Rice offers people in these countries, where rice is the staple diet, a lifesaving commodity (Reece, et al, 2012; Mayer, 2005)(See Figure 2).
Figure 2: A child who has become visually impaired due to vitamin A deficiency
Golden Rice is a genetically modified strain of rice which has had two β-carotene biosynthesis genes inserted into the rice genome (Reece, et al, 2012). The first gene was for the enzyme, Phytoene synthase, or PSY, from the daffodil (Narcissus pseudonarcissus) and the second gene for the enzyme, carotene desaturase, crt1, is taken from the soil bacterium, Erwinia uredovora (Reece, et al, 2012; Graham, 2010; Allen, et al, 2010). These two genes were then placed under the control of an endosperm-specific promoter, so that the genes were only expressed through the edible endosperm (Graham, 2010; Villano, 2000). The crt1 gene can catalyse multiple steps in the synthesis of carotenoids. This manipulation of the rice’s genome causes the production and accumulation of β-carotene, a precursor to Vitamin A, in the endosperm of the grain (Reece, et al, 2012; Rao, 2008; Sterger, 2011). When the rice is consumed, some carotenoids are converted into Vitamin A in the body. The modification of these genes affects the colour of the grain, causing the golden coloration. The intensity of the golden colour is an indicator of the concentration of β-carotene expressed in the grain (Graham, 2010; Rao, 2008). The first prototype of Golden Rice (SGR1) was developed in 1999, which produced 1.6μg/g of carotenoids, but in 2005 a new type with up to 23 times higher β-carotene content (37 μg/g) than SGR1 was generated (Reece, et al, 2012; Graham, 2010; Allen, et al, 2010). In the second generation of Golden Rice, they combined the Phytoene synthase gene from maize with the original crt1 from the soil bacterium (Allen, et al, 2010)(See Figure 3).
Figure 3: Flow chart of the chemical pathways involved in producing β-carotene in Golden Rice
The latest advances in genetic modification of crops now allows for fast, easy and efficient production of desirable traits in these foods and is far superior to all other alternatives. Genetically Modified Foods can greatly help the global community with the development of nutritionally-enhanced crops, such as Golden Rice. Golden Rice can help to reduce chronic health issues involved with vitamin A deficiency and it is critical that this life-saving food source is introduced on a global scale. However, this cutting-edge branch of Genetic Engineering requires further research to alleviate the concerns of the general public and hopefully this will allow greater use of Golden Rice and other GM foods, especially in developing countries.
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