(cm) Substitute the daffodil gene with the maize gene; with this recipe British scientists have succeeded in considerably raising the content of provitamin-A in Golden Rice. The starting point for the researchers was the original Golden Rice developed five years ago by Ingo Potrykus at ETH Zurich. In the new plant, known as Golden Rice 2, the provitamin-A content of the original rice is increased by up to 23-fold. This is significant, as one of the main criticisms levelled at the first version was that the level of provitamin-A in an average daily portion of rice did nothing to alleviate the serious problems caused by vitamin A deficiency.

For their study, which is published in the science magazine "Nature Biotechnology“ (1), the researchers started from the hypothesis that the daffodil gene responsible for encoding phytoene synthase was the limiting factor in the production of beta-carotene (a precursor of vitamin A) in Golden Rice. In order to test their hypothesis the researchers introduced the gene for the critical enzyme from various organisms into the maize cell, which subsequently developed a cell cluster called callus. They discovered that the maize version of the phytoene synthase gene leads to a greater enrichment of beta-carotene, while the daffodil variant fares the least well. In between there was the production, for example, which released the aradopsis thaliana gene....

When the researchers introduced the highly promising maize gene into the Golden Rice it led to a massive increase in provitamin A content in this new environment. Therefore the grains of rice glint more orange than golden. In a first estimation the researchers conclude that 72 grams of Golden Rice 2 would cover 50 per cent of the daily requirement of beta-carotene in a child's diet. Nonetheless, in their article the authors of the study warn that it is too early to deliver definite statements on the usefulness of Golden Rice 2, as the absorption of beta-carotene in the body still needed to be investigated.

In a press release Ingo Potrykus, as President of the Golden Rice Humanitarian Board, welcomes the development of Golden Rice 2. More research was needed to show how vitamin A deficiency could be combated with the new version. For all the success, Golden Rice was simply one tool in a far bigger toolbox.