Identification and Use of Rare Natural Genetic Sequence Variation to Improve Levels of β-Carotene in Maize

Sufficient vitamin A is not provided by a diet based mainly on corn Association mapping, validated by linkage mapping and expression studies, has been used to boost the nutritional value of corn. Corn, or maize, is a staple crop for many people in developing countries, but lacks sufficient micronutrients to provide a balanced diet by itself, particularly for growing children. Corn contains carotenoids, some of which the body can convert to vitamin A. Beta-carotene is the best provitamin A (vitamin A precursor), but only a very small percentage of corn varieties have naturally high beta-carotene levels. Markers found linked to genes encoding high levels of provitamin A in corn could speed the efficient development of corn cultivars that have the potential to reduce the number of children in developing countries who become blind, develop weakened immune systems, and die because of vitamin A deficiencies (VAD). In Africa alone, this number stands in the hundreds of thousands every year. Improving the micronutrient balance of staple crops such as maize through biofortification is an economically and socially sound way to address micronutrient malnutrition, including VAD, on a global scale. Daily dietary intake of maize with 15 μg g-1 provitamin A carotenoids could greatly alleviate VAD.1 Maize exhibits considerable natural variation for kernel carotenoids, with total carotenoid content ranging from virtually zero to nearly the 15 μg g-1 suggested levels; however most maize grown and consumed throughout the world has only 0.5 – 1.5 μg g-1 of β-carotene.