Naturally occurring genetic variants at the crtRB1 gene ― involved in synthesis of beta-carotene, a precursor of vitamin A ― are associated with increased levels of beta-carotene in maize, according to a report published online this week in Nature Genetics. These favorable variants are presently being bred into tropical maize grown in developing countries where vitamin A is needed to improve health.
In developing countries, vitamin A deficiency (VAD) leads to blindness in several hundred thousand children each year, half of whom die from VAD-related problems. Vitamin A biofortification of crops using naturally occurring genetic variants is one solution in combating VAD and other micronutrient malnutrition.
Using maize, Torbert Rocheford and colleagues surveyed naturally occurring variants of beta-carotene hydroxylases ― enzymes known to be involved in the synthesis of beta-carotene. The scientists identified a combination of genetic variants at crtRB1 that led to an average increase of beta-carotene in maize from a baseline level of 0.5 micrograms/gram to approximately 9 micrograms/gram.