The Philippines
July 20, 2011
In a major discovery, the International Rice Research Institute (IRRI) uncovered important genetic information on what makes rice chalky - an undesirable trait that can devalue the grain by up to 25%.
The discovery could lead to higher quality “chalk-free” rice. A chalk-free rice has higher milling recovery, which means better returns for farmers.
Chalk, the white, opaque portion in rice, increases the chances of the rice grain breaking when milled. This reduces the amount of rice recovered, and downgrades the quality assessment rating of rice.
“Two things cause chalkiness in a rice grain: genetics and environment,” explains Dr. Melissa Fitzgerald, leader of IRRI’s grain quality and nutrition research.
Farmers cannot answer for the genetics of rice; neither can they do anything about the environment. But one thing is clear -farmers want to keep their grains translucent and appealing to consumers to gain more from their field.
“Until now, rice scientists did not know where in the rice genome the genes for chalkiness resided,” asserts Dr. Fitzgerald. For more than 15 years, Dr. Fitzgerald has been trying to understand what makes rice chalky because understanding this will pave the way to creating chalk-free rice varieties.
“Currently, there are only a few commercially available rice varieties that have genuinely low chalkiness,” says Dr. Fitzgerald. “Our discovery can help us improve on this.”
Dr. Fitzgerald’s team, which includes Dr. Xiangqian Zhao, a postdoctoral research fellow, Dr. Adoracion Resurreccion, Ms. Venea Dara Daygon, and Mr. Ferdinand Salisi, worked with many lines of rice with different chalkiness properties.
In 2010, crucial data from field tests in eight different countries each with different growing environments came in. These field test results showed three groups of rice: rice that was always very high in chalkiness, rice that varied in chalkiness depending on the environment, and rice with extremely low chalk.
The third group of rice,the extremely low chalky ones, were further analyzed. From this, scientists were able to identify major regions in the rice genome, or candidate genes, that are responsible for chalkiness. The discovery of these regions puts IRRI scientists one step away from identifying the actual genes that give rice its chalky trait.
“We are now working with the extremely low-chalk rice to generate different breeding lines to develop new chalk-free rice varieties,” declares Dr Zhao. “These can help farmers increase the amount of edible rice they harvest, produce higher quality rice, increase profit, and deliver higher quality rice to consumers.”
This research is supported by the Australian Centre for International Agricultural Research.
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