Present and future of folate biofortification of crop plants.

Improving nutritional health is one of the major socio-economic challenges of the 21st century, especially with the continuously growing and ageing world population. Folate deficiency is an important and underestimated problem of micronutrient malnutrition affecting billions of people worldwide. More and more countries are adapting policies to fight folate deficiency, mostly by fortifying foods with folic acid. However, there is growing concern about this practice, calling for alternative or complementary strategies. In addition, fortification programmes are often inaccessible to remote and poor populations where folate deficiency is most prevalent. Enhancing folate content in staple crops by metabolic engineering is a promising, cost-effective strategy to eradicate folate malnutrition worldwide. Over the last decade, major progress has been made in this field. Nevertheless, engineering strategies have thus far been implemented on a handful of plant species only and need to be transferred to highly consumed staple crops to maximally reach target populations. Moreover, successful engineering strategies appear to be species-dependent, hence the need to adapt them in order to biofortify different staple crops with folate.