Biofortification of rice grains for increased iron content

Abstract

Dietary iron (Fe) deficiency affects 14% of the world population with significant health impacts. Biofortification is the process of increasing the density of vitamins and minerals in a crop, through conventional breeding, biotechnology approaches, or agronomic practices. This process has recently been shown to successfully alleviate micronutrient deficiency for populations with limited access to diverse diets in several countries. The Fe breeding target in the HarvestPlus program was set based on average rice consumption to fulfil 30% of the Estimated Average Requirement of Fe in women and children. In this review, we present the reported transgenic approaches to increase grain Fe. Insertion of a single or multiple genes encoding iron storage protein, metal transporter, or enzyme involved in the biosynthesis of metal chelator in the rice genome was shown to be a viable approach to significantly increase grain-Fe density. The most successful approach to reach the Fe breeding target was by overexpression of multiple genes. Despite this success, a significant effort of 8-10 years needs to be dedicated from the proof of concept to varietal release. This includes large-scale plant transformation, event selection, collection of data for premarket safety assurance, securing biosafety permits for consumption and propagation, and collection of data for variety registration.