Having identified genes in rice that are responsible for a low glycaemic index, IRRI scientists are now breeding new varieties adapted to global health problems such as diabetes.
Photo: © Shutterstock/Elamaran Elan Photography

A scientific breakthrough for low and ultra-low glycaemic index rice

In an effort to help curb the rising cases of diabetes globally, scientists from the International Rice Research Institute (IRRI), a CGIAR Research Center, have identified the genes responsible for low and ultra-low glycemic index (GI) in rice. This new discovery will be able to convert popular rice varieties into low and ultra-low GI for refined white rice, through conventional breeding methods, keeping high-quality grain and without compromising yield.

The first batch of ultra-low GI rice samples, developed from the Samba Mahsuri x IR36ae, was formally presented to Philippine President Ferdinand Marcos, Jr. at the opening ceremony of the 6th International Rice Congress, which took place from the 16th–23rd October. At the opening in Manila, Marcos said that the Congress was an important platform for promoting the development and use of more quality rice varieties and technologies such as the ultra-low glycaemic index or ultra-low GI rice.

IRRI has previously identified two low GI Philippine varieties, IRRI 147 and IRRI 125, that were already released in the Philippines as salt-tolerant varieties. Based on clinical validation on human volunteers in a cohort study, IRRI 147 depicted a GI value of 55 and IRRI 125 had a GI value of 51.1.

Diabetes growing globally at an epidemic rate

According to the International Diabetes Federation, there were 537 million people with diabetes in 2021 and this figure is expected to increase by 47 per cent by 2047. Many cultivated rice varieties have a GI ranging from 70 to 92, which is not considered healthy for people with diabetes.

IRRI classifies GI levels below 45 as ultra-low, 46-55 as low GI, 56-69 as intermediate GI, and high GI at 70 and above. The newly discovered ultra-low GI line has a GI level of 44, with translucent backgrounds.

In 2019, IRRI found highly significant marker-trait association markers for distinguishing intermediate versus high GI. The breakthrough comes in IRRI having now defined the genetics for low GI and ultra-low GI and developed pre-breeding lines in a high-yielding background with low GI and ultra-low GI characteristic features.

“IRRI's latest discovery offers the opportunity to develop rice varieties with low GI, and for the first time ever, ultra-low GI levels, to meet the health needs and dietary preferences of consumers,” said Dr Nese Sreenivasulu, Head of IRRI’s Consumer-driven Grain Quality and Nutrition Research Unit and lead of this discovery, adding that in collaboration with relevant institutions in different countries, these lines could also be used as donors to transfer low and ultra-low GI traits to popular rice varieties with different grain size and shape, as well as in different maturity backgrounds.

The low GI has a much lower glucose peak, and the ultra-low GI lines release glucose at an extremely slow rate, compared to high-quality conventional rice, which spikes sugar levels significantly within the same 40-minute window.

This scientific breakthrough comes from a wider South-South collaboration between IRRI scientists in the IRRI global headquarters hosted by the Philippines government and IRRI South Asia Regional Centre in Varanasi in India.

“These research breakthroughs possess much-needed health benefits and tremendous market potential. We look to partnering with as many national systems as possible to help fast track the release of low and especially the ultra-low GI rice varieties,” said IRRI Interim Director General Dr. Ajay Kohli, adding that the ultra-low GI variety would be market-ready within two years through a collaboration scheme between IRRI and PhilRice.


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