New research boosts vitamin A content in maize

By Laura Crowley

- Last updated on GMT

Related tags: Maize, Vitamin a, Genetics

Researchers have identified the genetic markers in corn that are
associated with high levels of vitamin A, providing a simple and
cost-effective way to cultivate maize rich in the nutrient.

The team, which included scientists from Cornell University, the University of Illinois and Boyce Thompson Institute, say that this innovation could help to enhance the nutritional status of millions of people in the developing world. The results from the study are published today in Science. ​The team found a mutant form of an enzyme vital to the cascade of chemical reactions that lead to the vitamin A precursors. This mutant is transcribed in lower quantities than the normal allele and encourages the production of beta-carotene, a form of provitamin A, which is a precursor converted to vitamin A upon consumption. "Maize is the dominant subsistence crop in much of Sub-SaharanAfricaand theAmericas, where between 17 and 30 per cent of children under the age of five are vitamin A deficient,"​ says the report. Maize contains a certain amount of beta-carotene. However, current maize varieties consumed in Africa can have levels of beta-carotene as low as 0.1 micrograms per gram. Vitamin A deficiency is a leading cause of eye disease as well as other health problems in the developing world. About 40m children are inflicted with eye diseases, and another 250m suffer from health problems resulting from a lack of Vitamin A. The researchers looked at 300 different maize lines and discovered an inexpensive way to screen different maize types to use varieties that come close to the target amount of 15 micrograms. Researcher Edward Buckler says in the report that his team's method for analysing the maize is simpler, faster and up to 1,000 times cheaper than some previous methods. For instance, a common technique called high performance chromatography, which assesses the provitamin A content of individual plant lines, costs between $50 and $75 for a single sample, according to the study report. This team of scientists used a variety of more affordable techniques in their analysis. They used quantitative trait loci mapping to identify regions of the maize chromosome that influence production of the provitamin A. They also used association mapping, which involves studying variation in selected genes and tracking inheritance patterns to see which form of a gene coincides with the highest beta-carotene content. Additionally, polymerase chain reaction allowed them to amplify and sequence the different alleles of interest, to find the ones that boosted levels of beta-caratone in the plant. James Collins, assistant director for the Biological Sciences Directorate at the National Science Foundation said: "In a field of thousands of ears of corn, each ear has a slightly different genetic makeup and resulting differences in physical characteristics. Therefore, identifying crops that have high levels of vitamin A precursors has traditionally been like finding a needle in a haystack." ​ The Buckler and Rocheford team is currently working with various international organisations, such as the International Maize and Wheat Improvement Centre to help train plant breeders in developing countries to use their techniques. Source: Science​ 18 January 2008, Volume 319, Pages 330-333, doi: 10.1126/science.1150255 "Natural Genetic Variation in Lycopene Epsilon Cyclase Tapped for Maize Biofortification"​Authors: C.E. Harjes, T.R. Rocheford, L. Bai, T.P. Brutnell, E.S. Buckler

Related topics: Research

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