Researchers identify gene that improves rice yields in poor soil

A gene that raises rice yields by enhancing root growth and nutrient absorption in low quality soils has been identified in a species of rice in India and successfully introduced into other rice varieties, researchers reported on Thursday.

Scientists and rice breeders have known for years that Kasalath rice is unusually efficient at nutrient absorption, but only now have they succeeded in identifying the gene responsible for this important trait.

In a paper published in the journal Nature, they described how they identified the gene after analyzing part of the Kasalath DNA where it was thought to be located and comparing it with other rice varieties without the trait.

Using conventional breeding methods, they introduced the gene into a few rice types in Indonesia, the Philippines and Japan and found that it raised yields by up to 20 percent.

"We found a gene that enhances phosphorus uptake in low phosphorus conditions. We have been looking for it for many years," said lead author Sigrid Heuer at the International Rice Research Institute in Manila.

Heuer said the superior breeding lines could be released to farmers in Indonesia in about 2-3 years. These have already been developed using conventional breeding methods -- by pollinating the flowers of a native Indonesian rice species with pollen from the Kasalath.

"As for other Asian countries, we will get them to put the gene into their local varieties through conventional breeding," said Heuer, adding that this would take about 4-5 years.

By using conventional breeding techniques, in this case, cross-pollination, there are no issues related to genetic modification. Food safety concerns and regulatory hurdles for transgenic rice -- where a gene is physically inserted into plant DNA in a laboratory -- can translate into years or even decades of testing before the strain reaches markets

The gene, PSTOL1, allows rice crops to thrive in soil that has low levels of phosphorus, a nutrient that promotes root growth, winter hardiness and hastens maturity. Plants deficient in phosphorus are often stunted.

"Fifty percent of world's arable land is too low in phosphorus. It's not like if you have this gene that the plants don't need phosphorus anymore," said Heuer.

"They (rice plants with the gene) may be able to exploit the soil a little better so the harvest is better. They may make better use of fertilizer because they can take it up more efficiently ... If you have a bigger root system, then the plant can take it up better and they can have better access to the patches where the phosphorus is."

[Source: By Tan Ee Lyn, Reuters, Hong Kong, 22Aug12]

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