What can rice scientists offer to a sugary world?

By Nese Sreenivasulu
Head of Grain Quality and Nutrition Centre, International Rice Research Institute (IRRI)

Countries undergoing economic transitions are also going through nutritional transformations. Along with rising disposable incomes and urbanisation, consumers are showing a propensity for convenient but highly processed foods, and for an increasingly sedentary lifestyle. Due to these factors, the world’s population is becoming progressively susceptible to “modern lifestyle” disorders – formally known as non-communicable diseases (NCDs) –  such as obesity, cardiovascular ailments, diet-related cancers and diabetes.


Obesity has become a global pandemic, affecting 5.5 billion people around the world. Approximately 420 million people worldwide suffer from Type 2 diabetes, which has been described as a “ticking time bomb.” The number of cases of cardiovascular ailments and diet-related cancers is also rapidly escalating in developing countries. Together, these ailments account for about 80 per cent of deaths caused by NCDs (WHO, 2011).

The global rise in modern lifestyle diseases calls for urgent attention to diet-based nutritional interventions across the entire socioeconomic consumer spectrum.

For consumers, making the right changes in their diets – for example, cutting down on junk food, sugary drinks and saturated fats – can bring about significant impact on their health in the long term.

However, the solution isn’t found in supermarkets, nor at dining tables; the problem needs to be addressed at an earlier stage: It is necessary to review the status quo in crop-breeding programmes, in order to diversify into more food products with greater health benefits.

The rapid turnover of starch, resulting in higher glucose spikes in the bloodstream, is a serious concern. This will lead to the development of Type 2 diabetes if the body cannot produce enough insulin, or is unable to properly use the insulin to control glucose levels in the bloodstream. An important avenue to explore is the development of staple grains with “healthy carbohydrates,” which are digested by the body more slowly. Grains that have higher dietary fibre and less digestible starch have a weaker effect on blood sugar levels.

The immense diversity of rice varieties in the International Rice Genebank could offer solutions in expanding breeding products with added value to healthy diet options. Recently, the International Rice Research Institute (IRRI) utilised high-throughput genomic resources to identify a genetic region in rice that enhances pure amylose, resulting in slower digestibility with unaltered cooking properties (Butardo et al., 2016). The study revealed the diagnostic markers for elevated pure amylose, which influences low glycaemic index (GI) response (based on k-value estimation of starch hydrolysis, by percentage) with acceptable cooking quality. This will create a unique opportunity to breed rice with low GI to provide consumers of rice with greater health benefits in combating type 2 diabetes and other “modern lifestyle” diseases.

Characterisation of digestibility and the cooking property of selected rice lines belonging to different haplotypes (groups of genes that were inherited together from a single parent), represented from chromosome 7, are shown in the graph below.


Photo credit: International Rice Research Institute (IRRI)

The k-values from cooked milled rice flour of representative lines from haplotypes 1, 4, and 8 are compared using a line graph. The k-values were overlaid with amylose fractions. Note that haplotype 1 represented lines showing rapid digestibility, haplotype 4 intermediate digestibility, and haplotype 8 slower digestibility. Representative seeds from haplotypes 1, 4, and 8 reveal that lines containing haplotype 8 are colored rice from Bangladesh and Sri Lanka.

These can be considered for precision breeding, which will facilitate the production of healthier cereal grains and processed food items to mitigate the impact of undernutrition and NCDs, which fuel some of the biggest health challenges of our time.

The International Rice Research Institute (IRRI) is the world’s premier research organisation dedicated to reducing poverty and hunger through rice science; improving the health and welfare of rice farmers and consumers; and protecting the rice-growing environment for future generations. IRRI is an independent, non-profit, research and educational institute, founded in 1960 by the Ford and Rockefeller foundations, with support from the Philippine government. The institute, headquartered in Los Baños, Philippines, has offices in 17 rice-growing countries in Asia and Africa, and over 1,000 staff.

Working with in-country partners, IRRI develops advanced rice varieties that yield more grain and better withstand pests and disease, as well as flooding, drought and other harmful effects of climate change.

Nese Sreenivasulu has 15 years of research experience in plant functional genomics of seed biology. Since 2013, he has led IRRI's Grain Quality and Nutrition Center and managed research programmes on grain quality. He provides scientific leadership for IRRI's research on the physical, sensory, cooking and nutritional qualities of rice grain. Leading a team of more than 30 staff members, he is currently focused on exploring the untapped genetic diversity of rice, to address grain quality using a multidisciplinary genomics strategy.

References 


Butardo VM Jr, Anacleto R, Parween S, Samson I, de Guzman K, Alhambra CM, Misra G, Sreenivasulu N. 2017. Systems Genetics Identifies a Novel Regulatory Domain of Amylose Synthesis. Plant Physiol. 173(1):887-906. doi: 10.1104/pp.16.01248.


Global status report on noncommunicable diseases 2010. 2011. WHO Press. World Health Organization. 


Published on 01 Feb 2017