Researchers at the Philippines’ International Rice Research Institute (IRRI) recently made a major genetics breakthrough, having discovered the genes responsible for “chalkiness" —an undesirable trait that can devalue rice by as much as 25 percent.
The high presence of “chalk" —the white, opaque portion of rice grains— increases the possibility of breakage during milling, thereby downgrading the quality assessment rating of rice.
Conversely, “chalk-free" rice is less likely to break, boosting potential returns for farmers by increasing the potential amount of rice that can be recovered.
Causes of chalkiness
“Two things cause chalkiness in a rice grain: genetics and environment," explains Dr. Melissa Fitzgerald, leader of IRRI’s grain quality and nutrition research.
But because the genetic factors were largely unknown, farmers could only do so much to the environment to provide optimal conditions for the growth of commercially-viable translucent rice grains.
Over 15 years of research
“Until now, rice scientists did not know where in the rice genome the genes for chalkiness resided," asserts Dr. Fitzgerald, a scientist who has been working on uncovering the genome behind chalkiness for more than 15 years.
“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. AdoracionResurreccion, Ms. VeneaDaraDaygon, and Mr. Ferdinand Salisi, worked with a number of rice varieties exhibiting various degrees of chalkiness.
Classification of rice varieties
Their research led them to group the varieties into three classifications: rice that was always very high in chalkiness; rice that varied in chalkiness depending on the environment; and rice with extremely low chalkiness. The groups were identified after data came from field tests done in eight countries with different growing environments.
The scientists, after analyzing the third group —the extremely low chalky ones— were able to identify major regions in the rice genome, or candidate genes responsible for chalkiness. The discovery puts IRRI scientists closer to identifying the actual genes causing 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." — TJD
