Phosphorus uptake gene 'could boost rice yields'
[MANILA] A rice gene that could significantly raise the rate of phosphorus uptake in rice varieties has been discovered by a team of international researchers, who claim that it could increase rice yields by up to 20 per cent.
The gene is called PSTOL1, which stands for Phosphorus Starvation Tolerance. It enhances the root growth of rice plants, enabling them to acquire more phosphorous and other nutrients locked in soils.
Sigrid Heuer, a senior scientist at the International Rice Research Institute (IRRI) in the Philippines, and leader of the team that published the study in Nature last week (22 August), said low phosphorus availability in soils affects about half of the world's farmlands. Affected soils require additional applications of phosphorous fertiliser to make them productive.
However, the global demand for such fertiliser is increasing. As a result, prices have almost tripled since 2005. For poor farmers who cannot afford the high prices, yields remain very low.
The discovery of the PSTOL1 gene will make it easier for breeders to develop new rice varieties with enhanced phosphorus uptake using breeding techniques, such as marker-assisted selection, since they will have confidence that the new varieties contain the gene.
Heuer told SciDev.Net that the PSTOL1 gene was found in Kasalath, a traditional rice variety from India. Kasalath belongs to the aus-type rice group that is also the source of the submergence tolerance gene, which IRRI has used to breed varieties suitable for growth under water that are being widely adopted in Asia.
She credited Matthias Wissuwa, a senior scientist at the Japan International Research Center for Agricultural Sciences, with initially discovering Kasalath's superior performance under poor soil conditions.
IRRI has yet to incorporate the gene into commercial varieties, but says it has enough seeds to act as breeding lines for use in trials.
According to Heuer, the most advanced breeding lines have been developed in Indonesia, by IRRI's partners at the Indonesian Center for Agricultural Biotechnology and Genetic Resources Research and Development. IRRI's own breeding lines are now being tested in India, and "if they perform well, they can be given to farmers within the next two or three years", Heuer says.
Emil Q. Javier, president of the National Academy of Science and Technology, and one of the Philippines' most prominent scientists, said that because phosphorus is a mineral nutrient required by all plants, other crops like corn could also benefit from the rice gene.
"This should be possible now, with genetic engineering," Javier said, as the desired gene could, in principle, be inserted into corn and other crops.
But Wilhelmina Pelegrina, senior campaigner for sustainable agriculture for Greenpeace International, suggested that caution was needed about transferring such a gene to other crops.
"While advancements in science make this possible, the question is whether it is necessary," Pelegrina said.
She added that many unanswered questions remain pertaining to genetically modified crops — particularly related to their long-term effects on humans and the environment — and reiterated that it would be wise to proceed with caution.