Status of biofortification in tropical root and tuber crops

Hidden hunger is a form of malnutrition, afflicting one-third of the world's population. It is caused due to the lack of micronutrients, mainly iron, zinc and vitamin A, in the human diet and can lead to mental impairment, poor health, low productivity and even death. It is common in many developing and developed countries. A change in research focus from increased agricultural production of calorie-rich staple crops to nutrient-dense staple crops is crucial to address the above problem. Biofortification is a process of increasing the density of vitamins and minerals in a crop through plant breeding, transgenic or recombinant DNA technology or agronomic practices. Biofortification through breeding has been taken up as a challenge by HarvestPlus for cassava and sweet potato, which has resulted in the release of many biofortified varieties that could fight hidden hunger and ensure food security in many Sub-Saharan African countries. The BioCassavaPlus project adopted transgenic strategies for biofortification in cassava. Transgenic approaches serve as an alternative for biofortification in sweet potatoes. HarvestPlus has not included yam in its biofortification programme, though increasing the provitamin A carotenoid content of yam is much needed. Bioavailability of micronutrients has been thoroughly studied in sweet potatoes. In India, the ICAR-Central Tuber Crop Research Institute (CTCRI), Thiruvananthapuram has been involved in the biofortification of tropical tuber crops and has released many biofortified varieties in sweet potato, cassava and yam. In a collaborative work plan with CIP, ICAR-CTCRI is at present involved in the development of biofortified varieties of sweet potato. The need to release and adopt transgenic biofortified crops is discussed here, as sweet potato is a naturally transgenic crop.