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Genes Identified to Boost Vitamin A in Corn

Orange corn

Orange corn, naturally high in carotenoids (Natalie van Hoose, Purdue University)

6 October 2014. Agricultural researchers at Purdue University identified a few key genes that can increase ingredients in corn for building vitamin A in humans. And because these genes are already found in some corn varieties, say the authors, new types of corn can be developed without transferring genes from other species. The team led by Purdue agronomist Torbert Rocheford — with colleagues from Purdue, Cornell, and Michigan State universities — published its findings last week in the journal Genetics.

Vitamin A deficiency is a condition that can lead to vision problems and according to World Health Organization is the main cause of preventable blindness, particularly in low income countries. It is considered a major public health problem in Africa and southeast Asia, affecting children and pregnant women, not only for vision problems, but also for increasing risks of severe infections. Lack of vitamin A can also contribute to macular degeneration among the elderly, a condition leading as well to blindness.

WHO estimates 250 million preschool children worldwide are deficient in vitamin A, and between 250,000 and 500,000 children become blind each year because of vitamin A deficiency. The source of vitamin A is a healthy diet rich in substances known as carotenoids used by humans to produce vitamin A, but in Sub-Saharan Africa, white corn is a staple food that has minimal amounts of carotenoids.

Rocheford and colleagues, therefore, sought to uncover genetic clues for producing corn varieties with higher quantities of carotenoids, known as orange corn since kernels on this corn turn a dark shade of orange. While orange corn is richer in carotenoids, it is not yet grown in Africa, but would likely be accepted by African corn growers, who can distinguish it from yellow corn that is fed to cattle.

The researchers conducted a genome-wide association study, a type of intensive genomic survey,of 201 lines of corn to reveal aspects of the corn genome most associated with carotenoid levels. Rocheford’s lab previously identified two genes linked to carotenoid production, but sought other genes associated with carotenoids, as well as to better understand the genetic pathways or processes for their production in corn.

The initial association study uncovered two genes not previously linked to carotenoid production. A further analysis of 58 gene candidates previously associated with nutrient processes revealed two more genes linked to carotenoid traits. In addition, the researchers analyzed a small number of quantitative trait loci, a statistical method connecting genomic characteristics to physical traits like carotenoid production, to identify genetic predictors of carotenoid production.

The genomic analysis and statistical models yielded data to outline a strategy for quickly developing new varieties of high-carotenoid corn that can be grown by farmers in Africa without introducing genes from other plant species. The Purdue team is already working with international agricultural groups including HarvestPlus and the International Wheat and Maize Improvement Center experimenting with some orange corn varieties.

“We now have the genetic information needed,” says Rocheford in a university statement, “to begin developing a major public-private sector collaboration with the goal of providing orange corn with high levels of provitamin A to farmers throughout Sub-Saharan Africa.”

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