From: Editor, ENN
Published August 23, 2012 02:29 PM

Rice Genes

Rice is a cereal grain, it is the most important staple food for a large part of the world's human population, especially in Asia and the West Indies. It is the grain with the second-highest worldwide production, after maize (corn), according to data for 2010. Since a large portion of maize crops are grown for purposes other than human consumption, rice is the most important grain with regard to human nutrition and caloric intake, providing more than one fifth of the calories consumed worldwide by the human species Scientists have now pinpointed a gene that enables rice plants to produce around 20% more grain by increasing uptake of phosphorus, an important, but limited, plant nutrient. The discovery unlocks the potential to improve the food security of rice farmers with the lowest value phosphorus-deficient land allowing them to grow more rice to add to global production, and earn more.

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As of 2009 world food consumption of rice was 531,639 thousands metric tons of paddy equivalent , while the far largest consumers were China consuming 156,312 thousands metric tons of paddy equivalent (29.4 % of the world consumption) and India consuming 123,508 thousands metric tons of paddy equivalent (23.3% of the world consumption). Between 1961 and 2002, per capita consumption of rice increased by 40%.

The studied gene — called PSTOL1 which stands for Phosphorus Starvation Tolerance — helps rice grow a larger, better root system and thereby access more phosphorus. Farmers can apply phosphorus fertilizers to increase productivity but on problem soils phosphorus is often locked in the soil and unavailable to plants.

Also, phosphorus fertilizer is often unaffordable to poor farmers. Adding to the problem is that phosphorus is a non-renewable natural resource and rock phosphate reserves — the source of most phosphorus fertilizers — are running out.

"We have now hit the jackpot and found PSTOL1, the major gene responsible for improved phosphorus uptake and understand how it works," Heuer (author) said.

According to Dr. Wricha Tyagi at the School of Crop Improvement at the Central Agricultural University in the Indian state of Meghalaya, knowledge of the exact gene will be critical for future breeding programs suited to Eastern and North-Eastern — parts of India where rice productivity is less than 40% of the national average due to acidic soil and poor availability of phosphorus.

Dr. Joko Prasetiyono, of the Institute for Agricultural Biotechnology and Genetic Resources Research and Development in Indonesia, is breeding rice plants with the PSTOL1 gene. The plants are not genetically modified just bred using smart modern breeding techniques.

"In field tests in Indonesia and the Philippines, rice with the PSTOL1 gene produced about 20% more grain than rice without the gene," said Heuer.

"In our pot experiments," she added, "when we use soil that is really low in phosphorus, we see yield increases of 60% and more, suggesting it will be very effective in soils low in phosphorus such as in upland rice fields that are not irrigated and where farmers are often very poor."

The discovery also demonstrates the importance of conserving the genetic diversity of traditional crop varieties such as Kasalath. IRRI conserves more than 114,000 different types of rice in the International Rice Genebank.

For further information see New Gene.

Rice image via Wikipedia.

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