In rice, beta-carotene (the pre-cursor of vitamin A), is not present in the grain endosperm, but in the leaves and stalks (apart from minute amounts contained in unmilled brown rice), and does not provide this critical micronutrient in sufficient amounts. Golden Rice, named after its distinctive colour, was developed by Ingo Potrykus of the Swiss Federal Institute of Technology, and his colleague Peter Beyer of the University of Freiburg to try to address the 250 million preschool children who are vitamin A deficient, a state that can lead to blindness and even death.
To create ‘golden rice,’ 2 daffodil and 1 bacterial gene were first transferred into rice as a way of increasing its beta-carotene content. The biochemical pathway leading to beta-carotene is largely present in the rice grain but lacks 2 crucial enzymes: photogene synthase (psy) – provided by a daffodil gene – and carotene desaturise (crt1I) – provided by a bacterium gene. In the greenhouse this transfer elevated beta-carotene levels to 1.6 μg/g, which is significant but not large. Subsequently, scientists at Syngenta have found new versions of the psy gene in maize; which when introduced to rice increasing the beta-carotene levels to 31 μg/g. Given a conversion ratio of beta-carotene to vitamin A of 4:1, the new golden rice (Golden Rice 2) will be able to provide the necessary boost to daily diets, even after 6 months of storage.
Golden Rice 2 has already been developed into locally appropriate varieties in the Philippines and India and in 2010 was forecast to be available in other countries in the next two to four years, but public opposition to genetic modification (GM) continues to delay regulatory approval. The consequent benefits to Asia’s GDP have been estimated at $18 billion annually.