Genetic technologies to enhance crop nutritional value under climate change.

At present, more than 700 million people live with caloric hunger, and more than two billion suffer from micronutrient deficiencies, known as 'hidden hunger'. From an agricultural viewpoint, three major objectives need to be worked towards simultaneously to achieve zero hunger (the United Nations Sustainable Development Goal 2): (1) enhanced yield; (2) higher vitamin and mineral density to sustain recommended daily intake (multi-biofortification); and (3) enhanced climate-change resilience. Although the Green Revolution increased global calorie production, it exacerbated hidden hunger by prioritizing high yield over nutritional quality. Stress from global climate change has been shown to reduce the densities of several micronutrients. CRISPR-Cas, which allows genome editing with extremely high precision, has emerged as a groundbreaking breeding technology that has already been adopted by many countries. Here we examine how CRISPR-Cas-based approaches could be used to achieve biofortification targets by enhancing micronutrient densities to the levels necessary to alleviate dietary vitamin and mineral deficiencies. Given the limited time frame available to achieve zero hunger, we argue that CRISPR-Cas technologies should be combined with metabolic engineering based on transformation and other technologies. We also consider untapped resources beyond metabolic pathways and current CRISPR-Cas methodologies to address one of the most important societal issues of the twenty-first century.