अप्रैल-जून 2012

Achieving food security is one of the priorities on the national agenda. At the current rate of population growth, it would be a challenging task to ensure food security which, as per the Food and Agriculture Organization, 'Exists when all people at all times have both physical and economic access to sufficient, safe and nutritious food that meets their dietary needs for an active and healthy life'.

Presently, more than half of world's population is malnourished particularly in the developing countries. As for India, the problem of micronutrient malnutrition is quite rampant especially in pregnant women and pre-school children. More than 50% pregnant women are anaemic and three out of four children below 5 years also suffer from iron deficiency. Similarly, millions of young children suffer from vitamin A deficiency leading to blindness. To be healthy and active, the human body needs more than 20 mineral elements and about 40 essential nutrients like vitamins and amino acids. Most commonly observed deficiencies in unbalanced diet are iron (Fe), zinc (Zn), calcium (Ca), iodine (I), magnesium (Mg), selenium (Se) and vitamin A. One of the approaches to address micronutrient malnutrition is through food fortification, such as enrichment of corn flakes with iron and calcium. Another practical way of combating hidden hunger would be through a novel way of 'Bio-fortification' of staple food crops. Bio-fortification refers to the genetic enrichment of food crops with enhanced level of desirable nutrients. Bio-fortified foods can supply essential nutrients year after year to the consumers, without much additional cost. Thus, bio-fortification is a cost-effective, long-lasting and sustainable approach to combat the problem of micronutrient malnutrition. Bio-fortification is attempted in staple food crops that are deficient in certain micronutrients by incorporating the gene(s) to synthesize a particular nutrient which is deficient in that particular crop. For example, enrich rice with higher vitamin A content which is not available in rice. The strategy of bio-fortification to supply micronutrients especially in developing countries involves making the staple foods they eat more nutritious by using both conventional plant breeding and biotechnological approaches. Conventional plant breeding could be successful when there is good variability for the traits of our interest between the crop species and within the crop itself. Several studies have indicated that there are considerable genetic variations in the mineral concentrations of most of the crops. Even in cereals, enormous genetic variability for protein, iron and zinc has been observed, as for example, there is 4- to 5-fold variation for iron content in rice.

Nutritional content of various food crops; animal foods and fish in Indian context

Nutritional content of various food crops; animal foods and fish in Indian context
Food Protein (g/100 g) Iron (mg/100 g) Zinc(mg/100 g)
Cereals 2.5- 10.5 1.3- 6.5 1.1- 2.2
Pulses 11.0-25.1 3.9- 5.9 2.0- 2.6
Fruits 0.2- 1.1 ~0.1 ~0.1
Vegetables 0.6- 3.0 ~0.3 ~0.2

Conventional plant breeding has good potential to increase the micronutrient density in staple food crops by careful screening of diverse genotypes, identifying the potential donors, making crosses and selection of genotypes having higher micronutrient content. This variability allows the plant breeders to improve the levels of micronutrients through simple breeding programmes. The success of developing quality protein maize (QPM) is one of the best examples of bio-fortification through conventional breeding programmes. Several QPM hybrids are now available and similar efforts are under progress in other crops as well.

Presently, several organizations are making concerted efforts to enhance the contents of iron, zinc, vitamin A and other minerals in staple food crops. Orangeflesh sweet potato lines with high levels of α- carotene (> 200 μg/g) and high-yielding beans with 50-70% higher iron content have been developed by conventional plant breeding. These conventional plant breeding approaches may be complemented with molecular marker-assisted selection to hasten the process of breeding. Such markers were identified for iron and zinc in rice which could be utilized in MAS. In cases where the genetic variability for the micronutrients is limited, efforts are needed to introduce such traits from related species and other sources. The popular example of this kind of bio-fortification is 'Golden Rice' which is enriched with α-carotene. Two versions of Golden rice have been developed and were donated to Golden Rice Humanitarian Board and among the six events of Golden Rice, 2 were developed in the background of the American Kaybonnet variety. Marker-assisted introgression of these genes through backcross breeding in the background of Indian popular varieties is under progress at the Indian Agricultural Research Institute, New Delhi; Directorate of Rice Research, Hyderabad; and Tamil Nadu Agricultural University, Coimbatore. Efforts are also being made to improve α- carotenoid content in cassava, sweet potato, maize, wheat and banana. The concept of bio-fortified food is new to our society and therefore, besides intensifying research efforts on bio-fortified crops, it is not only necessary to create awareness about these cost-effective healthy foods but also to conduct impact assessment of these bio-fortified foods. Public acceptance of the bio-fortified food is also important especially in view of the change in colour of the products, for example Golden colour of vitamin A rich rice. Proper awareness campaigns have to be conducted to sensitize the consumers about the importance of micronutrient-rich foods in their diets. Efforts are also needed to reward the farmers who grow nutririch crops with higher price to encourage them to grow such bio-fortified crops. Initially research efforts of agriculture were prioritized for achieving the self-sufficiency for foodgrains and now the scope is also extended to the biofortification of staple food crops as a strategy to address the malnutrition problem. With a view to provide thrust to the bio-fortification, the ICAR, in the ongoing XII Five-Year Plan, is contemplating a research platform on bio-fortification wheat, maize, sorghum and millets. The programme would focus on evaluation of diverse genotypes as potential sources of micronutrients and introgression of high micronutrient in high-yielding popular varieties of staple food crops. The research products would also require a strong policy and public support for their popularization which in the long run, could effectively be used to overcome micronutrient deficiencies in the human diet.