Authors: VANITA PANDEY, SEWA RAM, SNEH NARWAL, RINKI & PRIYANKA CHANDRA
The micronutrient deficiencies, particularly arising from zinc and iron, have been reported to cause serious health problems for more than two billion people worldwide. Iron deficiency anemia is by far the most widespread micronutrient deficiency, and it results in impaired physical growth, mental development, and learning capacity ( WHO, 2012). Numerous health problems link zinc deficiency to retarded growth, skeletal abnormalities, delayed wound healing, increased abortion risk, and diarrhea. The situation is even more adverse in developing countries where more than half of the children and pregnant women are suffering from iron and zinc deficiencies (Carter et al. 2010). This condition is largely attributed to the high consumption of cereal based foods, like rice, wheat and maize in these countries as the edible parts (endosperms) of modern cereal cultivars are inherently poor in iron and zinc minerals (Bouis et al., 2011). Iron and zinc concentration in whole grain of wheat are in the range of 29 to 73 mg/kg and 7 to 85 mg/kg, respectively. However, more than 75% of these nutrients are located in the seedy parts other than endosperm is lost during milling, ensuing in mineral deficient end products. Several strategies can be employed to alleviate the prevailing micronutrient deficiency, like:
- Dietary diversification
- Increasing the overall mineral content in seed grains.
- Increasing the levels of nutrients and compounds that promote bioavailability of essential minerals.
- Reducing the level of antinutrients in the food staples which reduce the bioavailability of dietary essential minerals.
Importance of biofortification in cereals
Wheat and rice are the major food crops of the world, contributing most to the edible dry matter production and up to 90% of the daily energy intake in several developing and developed countries (Wang et al., 2011). Therefore, the composition and nutritional quality of the cereal grains have a significant impact on human health and the enhancement of their nutritional profile which can significantly alleviate malnutrition for the economically weaker section of the society ( Welch and Graham, 2004). Biofortification in cereals can be successfully achieved through genetic or agronomic interventions.
- Genetic biofortification
Another aspect of genetic biofortification involves reduction of inhibitors of mineral absorption or availability like phytic acid ( Bouis, 2003). This involves increased expression of its degradation genes like phytase or silencing of the genes involved in phytic acid biosynthesis and transport. Both the strategies are under consideration and significant research is being done.
Genetic biofortification is more cost effective than food fortification, supplementation or dietary diversification in the long run, because it requires only one period of (breeding) investments.
- Agronomic Biofortification
Agronomic biofortification is often considered as a short-term solution to increase micronutrient availability and is mainly used to complement genetic biofortification (breeding). Agronomic biofortification through fertilizer approaches could complement the existing breeding approach; for instance, foliar application of zinc fertilizer can increase grain zinc above the breeding target set by nutritionists.
Biofortification of cereals is the most promising intervention to overcome iron and zinc malnutrition due to its cost-effectiveness. Bioavailability of iron and zinc from cereal grains can be increased by genetic interventions by modulating accumulation of either anti-nutrient agents or prebiotics. Enhanced accumulation of iron and zinc in cereal grains can be achieved by fertilization or genetically manipulating iron and/or zinc homeostasis-related genes. Future research should involve analyzing the accumulation of iron and zinc in the edible parts of cereal grains rather than whole grains. It is also advised that the impact of genetic modifications on the agronomic performance of crops, including grain yield, drought tolerance, insect resistance, disease resistance, and so on should also be assessed. In addition, the focus should be on studies involving field crop trials and human beings as experimental subjects to analyze the effectiveness of agronomic or genetic biofortification.
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About Author / Additional Info:
VANITA PANDEY and RINKI are Scientist, SEWA RAM and SNEH NARWAL are Principal Scientist at ICAR-IIWBR, Karnal; and PRIYANKA CHANDRA is Scientist at ICAR-CSSRI, Karnal.