Jan. 17, 2008

Genetic discovery can boost the provitamin A content of Africa's maize

Up to 250 million children, many in the sub-Saharan Africa region, are at risk each year for health disorders -- including 40 million who develop a sight-threatening eye disease -- all because they do not get enough vitamin A in their diet.

A new discovery, spearheaded by Cornell and University of Illinois plant geneticists and published in the Jan. 18 issue of the journal Science, could change all that. Using genetic and statistical tools, researchers have identified a set of genetic variants in maize that accounts for levels of vitamin A precursors among varieties.

The research could lead to at least tripling the provitamin A levels [the precursor to vitamin A] in Africa's maize, said senior author Edward Buckler, a U.S. Department of Agriculture-Agricultural Research Station research geneticist in Cornell's Institute for Genomic Diversity and Cornell adjunct associate professor of plant breeding and genetics.

"By identifying these genetic variants, breeders can make varieties with higher provitamin A rapidly and inexpensively," said Buckler. "This research will now go into the major effort to help create maize varieties in sub-Saharan Africa for subsistence farmers."

These improved crops, he noted, will not be genetically engineered but use the natural variation that is found in maize varieties, unlike rice, which has no genetic variation for provitamin A and so scientists use transgenes, or genetic engineering, to boost its provitamin A content.

Maize is the dominant subsistence crop in sub-Saharan Africa and Latin America, where 17 percent to 30 percent of children under age 5 are vitamin A deficient, said Buckler.

"Since maize is consumed for all three meals a day in much of Africa, maize is a good target for biofortification," he added.

Buckler is credited with improving association mapping, one of the methods used for this research, that is being used to understand the genetic basis of such complex traits as vitamin A content, drought tolerance, nitrogen use, carbon metabolism, disease resistance, and crop and milk yields.

The research was supported by the National Science Foundation, the U.S. Department of Agriculture and the Harvest Plus program.