Micronutrient deficiency is a global health problem that concerns nearly 2 billion people worldwide. Researchers developed a promising approach that could greatly improve the nutritional quality of agricultural crops, by modifying multiple nutritional traits in a single rice variety for the very first time.
In a world where a third of the population suffers from hidden hunger, better known as micronutrient malnutrition, food fortification seems like a promising solution. The practice of deliberately increasing the amount of essential micronutrients in food has a profound impact on developing countries, where almost 50% of the populations´ daily calorie intake is met with rice. As an answer to the existing situation, researchers from Laboratory of Plant Biotechnology, ETH Zurich, have developed a new enriched rice variety.
Rice represents the main dish in Asia and its consumption is rapidly increasing in Africa as well. Although it does help with stopping hunger, rice is generally a poor source of essential nutrients (black rice being a possible exception), especially vitamins and minerals. Consequently, people relying on rice tend to not consume enough iron, zinc and vitamin A to meet daily health recommendations. While zinc plays an essential role in numerous biochemical pathways, insufficient iron intake results in anemia, delays brain development and increases mortality among women and infants. Deficiency of vitamin A can cause blindness and can weaken the immune system, making people more vulnerable to measles, diarrhea, and malaria.
To battle this emerging crisis, rice can be fortified by addition of a micronutrient powder that adheres to the grains, or by spraying a vitamin and mineral mix directly over the plant´s surface in several layers. An even better solution is biofortification of rice, which increases its mineral concentration. To fight malnutrition, ETH researchers previously developed a rice variety known as “Golden Rice“, which is a genetically modified variety that produces beta-carotene, a precursor of vitamin A, in the endosperm of the rice grain. Golden Rice was since improved and is now used in breeding programs in several countries. To address other micronutrient deficiencies researchers also developed varieties with increased iron and zinc levels in rice and wheat grains.
So far, all transgenic rice varieties could only provide one particular micronutrient. A new variety developed by the group led by Navreet Bhullar represents the first multi-nutrient rice. In their recently published paper, the group reports they were able to produce the novel rice variety by engineering a gene cassette containing four genes for micronutrient amplification that could be inserted into the plant´s genome as a single genetic locus. This way, iron, zinc, and beta-carotene levels can be simultaneously increased by genetic crosses in rice varieties of various countries. A lesser alternative would be to cross rice lines with individual micronutrients to achieve improved micronutrient content in rice grains.
“Our results demonstrate that it is possible to combine several essential micronutrients — iron, zinc and beta-carotene – in a single rice plant for healthy nutrition,” explains Bhullar.
Their plants have been grown in a greenhouse and analyzed for their micronutrient content. Starting next year, the researchers intend to test the plants in confined field trials, to determine if the micronutrient traits and agronomic properties are equally robust in the field as they were in the greenhouse. “It will probably be five years before the multi-nutrient rice can be used to reduce hidden hunger,” she says. For now, the grains of the multi-nutrient rice lines have more beta-carotene than the original Japonica rice variety and less than in the improved variant of Golden Rice. “We will improve the lines further,” says Bhullar.
“If one would substitute 70 percent of the currently consumed white rice with the multi-nutrient variety, this could markedly improve vitamin A supplementation already in addition to sufficient iron and zinc in the diet,” Bhullar emphasizes.
The mission of Dr. Bhullar´s and similar endeavors is to hopefully one day greatly reduce the number of malnourished people with dietary deficiencies and bring a stop to the ever-growing concern of third-world hunger.
Learn more about golden rice in the video below:
By Andreja Gregorič, MSc