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[MANILA] Scientists say they have made a breakthrough in their quest to develop a rice variety to address iron and zinc deficiencies that affect millions of people in poor countries across Asia.
The genetically modified (GM) rice has up to four times more iron than conventional rice and twice as much zinc, Alex Johnson, from the Australian Centre for Plant Functional Genomics (ACPFG) told SciDev.Net.
"The rice has some of the highest iron concentrations that have been described for white rice (up to 19 parts per million). We have also demonstrated that the iron is in the endosperm tissue that makes up white rice," Johnson said. This is important because of the widespread consumption of white rice.
"This new report documents the early and exciting results for one approach for increasing the iron content of the rice grain," said Gerard Barry, leader of the Rice Crop Team of the US-based HarvestPlus, which partially funded the research. "The increase in iron in the polished grain is very important in terms of human nutrition."
HarvestPlus, which promotes biofortification research, usually focuses on conventional plant-breeding methods. But increasing the level of iron in rice is hard to achieve through conventional breeding because there are few naturally occurring varieties of rice with higher concentrations of iron to kick off the breeding process.
Johnson and his team focused on nicotianamine, a substance that occurs naturally in rice and helps it to take up iron from the soil. Normally, it is low levels of iron in the soil that signal to the rice to switch on the genes that control the production of nicotianamine. The scientists have succeeded in keeping these genes switched on all the time.
The method also boosted zinc levels.
Johnson said that, since nicotianamine naturally occurs in rice, consumption was unlikely to have any adverse health effects.
But he said it would take ten years before the new rice variety could be released for human consumption, because of the need for evaluation in the field over several seasons, and the need for bioavailability studies to discover whether animals actually absorb the iron.
Field trials have begun at the Philippines-based International Rice Research Institute (IRRI).
References
PLoS ONE doi:10.1371/journal.pone.0024476
Comments (3)
ironjustice ( Canada )
28 September 2011
Theoretically boosting the iron levels 'may' induce more infection in the plant. Phytic acid / phytate in the plant binds up iron and effectively removes the iron from fungal infection. IF the iron is raised it 'may' raise the levels of iron TO the point fungal infection CAN acquire it ? Therefore leading to loss of crops and high liver cancer rates due to aflatoxin / fungus infection ?
Kumar Pathirana ( Sri Lanka )
3 October 2011
Correct me if I am wrong. Although rice grain is low in protein content (about 7% in the dry grain), the quality of protein is near the top in the protein quality of plant food sources. However, lysin is its 1st limiting amino acid. A source rich in lysin such as dahl, or any lentil family grain apart from animal protein sources would immensely improve its qualty towards the top in plant protein sources. Rice is the main staple in many countries and the population obtain a significant quantity of protein from rice due to the relatively large amount consumed (for e.g. Sri Lankans obtain the highest amount of protein from rice). Therefore, if the lysin content in rice can be increased like high lysine corm bred for cattle), that would be a highly significant achievement.
Kumar K Pathirana
N Sarla ( India )
3 October 2011
One more excellent example of expression of a single gene being sufficient to alter expression of a complex trait.
However,it may not be quite correct to say "But increasing the level of iron in rice is hard to achieve through conventional breeding because there are few naturally occurring varieties of rice with higher concentrations of iron to kick off the breeding process." It is known that deep water rices, aromatic rices and several wild rice accessions have high iron and zinc concentration in seed and conventional, non-transgenic approaches can very well help increase iron and zinc concentration in popular, elite cultivars. Our unpublished results show that advanced backcross lines or introgression lines derived from elite x wild crosses and others derived from crosses between Swarna and deep water rice varieties such as Madhukar and Jalmagna indeed have more than two fold high iron and zinc concentration in brown rice. Whether these high yielding lines breed true for these traits over several generations, the concentration in polished grains and bioavailability needs to be ascertained.
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20 June 2013