The 1980s saw the development of the technologies required to introduce (transform) and express genes in plants. Transformation and regeneration of monocots (i.e. the group of plants that includes cereals, grasses, lillies, etc) was harder to obtain than that of their dicot counterparts and were achieved by the end of the decade. This was the area of expertise of Ingo Potrykus, who was a professor at the Swiss Federal Institute of Technology in Zurich.

Most of the science required to engineer the carotenoid pathway in the rice (a monocot) grain was developed in the 1990s. This is the area of expertise of Peter Beyer, where he has notably contributed to a better understanding of the underlying biochemical mechanisms involved.

The breakthrough achievement of 1999 showed that it was possible to reconstitute the carotenoid pathway in rice grains, something even many experts did not believe was possible. After the proof of concept was achieved, the project entered into the product development phase. One of the tasks during product development is to obtain regulatory approval, which is required by every country for the release of genetically modified plants into the environment. This is a mandatory step, which at present is overly lengthy and costly—it can cost several million dollars because of the extensive toxicity and allergenicity testing involved, comparable to those applicable to the pharmaceutical industry.

Access to Intellectual Property Rights (IPR) —which many thought would be the main technology access barrier to the Golden Rice technology— was achieved in 2000, a process that took less than six months of negotiations. The deal involved the creation of a private-public partnership between the inventors and the agrichemicals company Syngenta. This partnership facilitated the access to a number of key technologies held by multiple players in the field of biotechnology. The required material transfer agreements (MTAs) were signed in 2001.

The next necessary step consisted in identifying a partner capable of producing hundreds of transgenic rice lines from which regulatory clean events could be identified. The term regulatory clean refers to individual transformants (plants derived from one singly genetically modified cell) capable of complying with the multitude of regulatory requirements. A number of such events are still being tested to decide which one will reach the farmers in the end.

It was shown early in the process that the Golden trait could be transferred to indica rice varieties, which are widely grown and eaten SE Asia, where vitamin A deficiency is rampant. But these varietie are also technically the most difficult to transform. Once a useful transformation event has been obtained in a rice variety belonging to any of the cultivated varietal groups (japonica, indica, javanica), the trait can be transferred from one variety to the other by conventional breeding techniques. Alternatively, the necessary genes can be introduced directly by genetic transformation. The latter is the less preferred option, at least as long as the regulatory approval procedures remain as demanding as they are at present, i.e. the whole regulatory package must be produced for each transformation event, even if the same genes are introduced.

The first regulatory clean event was obtained in 2002, and a regulatory clean line with a β-carotene content of 1.6 µg/g was obtained in 2003.

The first Golden Rice field trial in the world was harvested in September 2004 in Louisiana, USA. It may sound surprising to many that five years went by before Golden Rice could be planted in an open field. A main reason for this delay was that target countries for Golden Rice —i.e. those with high rice consumtpion and a high vitamin A deficit— did not have biosafety regulations in place at the time. A necessary condition attached to the agreement with Golden Rice licensees is that no field releases may take place in the absence of a national a regulatory framework. The delay shows how complicated life has become for developing countries. Even in the face of human misery, that could be alleviated with the help of a transgenic plant, developing countries are still struggling with multiple pressures that make access to the technology almost impossible.

The reason the first field trial was carried out in collaboration with Louisiana State University, is that the USA is one of the few countries in the world where field trials with transgenic plants can be carried out after complying with an acceptable, well-defined set of regulatory requirements.

In the field, the transgenic Golden Rice plants were indistinguishable from their parent variety, while β-carotene accumulation was higher than for parental materials grown in the greenhouse. While β-carotene in first generation Golden Rice was not high enough to cover the recommended daily requirements of people with acute vitamin A deficiency, the experiment showed that, in the field, grains accumulated about four times more β-carotene than in the greenhouse, possibly due to better growth conditions. An average of 6 µg/g β-carotene was obtained for the grains from the 2004 field trial. The same year, new experimental lines (GR2) with more than six times as much β- carotene were obtained in the greenhouse!, which is 23 times more than in the prototype Golden Rice obtained in 1999 (If you are interested in that new development follow this link).

A recount of the Golden Rice story by Ingo Potrykus can be found at "The Golden Rice Tale".