GENET archive


2-Plants: Non-GE approaches for iron-rich maize

genet-news mailing list

-------------------------------- GENET-news --------------------------------

TITLE:  Pumping Iron Into Western Africa's Corn
SOURCE: U.S. Department of Agriculture, Agricultural Research magazine, by Lois 
DATE:   April 2003

------------------ archive: ------------------

Pumping Iron Into Western Africa's Corn

Iron deficiency anemia is endemic throughout western Africa. It afflicts more 
than half the children and 61 percent of childbearing-age women in Nigeria. In 
Burkina Faso, 70 percent of children under age 5 and 40 percent of pregnant 
women are anemic.

Iron is essential to the formation of hemoglobin, an important oxygen-carrying 
component of red blood cells. Iron deficiency can retard mental development and 
impair physical growth in children and adolescents and often leads to anemia, 
which is a deficiency of red blood cells. Anemia can lower disease resistance, 
complicate pregnancies, and reduce capacity for physical labor.

Preventing iron deficiency and anemia in resource-poor areas is extremely 
difficult, as people have little choice but to eat foods low in bioavailable 
iron, and fortification programs are not available.

Undaunted, scientists at ARS' U.S. Plant, Soil, and Nutrition Research 
Laboratory in Ithaca, New York, and a Nigeria-based international agricultural 
organization have teamed to meet this challenge. They have made maize, one of 
the region's staple crops, the centerpiece of their work.

Improving a Good Thing

Through a process called biofortification, the researchers seek to boost the 
nutrition that western Africa's residents get from maize by simply making 
available - and popular - the iron-rich varieties already bred, grown, and 
consumed there.

"People in many areas of western Africa are eating maize that is not as 
nutritious as other varieties because it has low levels of available iron that 
the body can absorb during digestion," says the project's leader, Ithaca-based 
ARS human physiologist Raymond P. Glahn. "We need to get maize to them that has 
more bioavailable iron. We estimate they need to absorb about 20 to 30 percent 
more iron from maize than what they are currently getting."

This can be accomplished through conventional plant breeding, he says. "But the 
starting point is identifying the iron-rich strains already growing in the 
region and finding which of those strains are most adaptable to all the region's 
land and climate zones."

Finding the Best of the Best

The project combined the regional agricultural knowledge of the International 
Institute of Tropical Technology (IITA), which is headquartered in Idadan, 
Nigeria, with some of ARS' latest technology, namely an in-vitro artificial gut 
Glahn invented during the late 1990s. (See "A Gut Issue - Measuring Iron 
Bioavailability," Agricultural Research, August 1999, p. 4.) The model mimics 
human digestion to the point where nutrients are actually absorbed by a line of 
human intestinal cells.

The scientists used the artificial gut to evaluate and rank iron bioavailability 
in kernels of elite maize varieties grown in diverse environments. They examined 
69 corn varieties that have historically shown acceptable results in grain yield 
and disease resistance.

"The model is what made this research possible," says Glahn. "You could not do 
what we did - screen a whole library of maize samples - using human or animal 
subjects, as the costs would be enormous."

Glahn began the project after being inspired by recent studies showing that 
significant differences exist in iron concentration in maize kernels. According 
to Sylvester O. Oikeh, an IITA soil fertility and plant nutrition specialist 
assisting Glahn in Ithaca, those differences were due to genetic differences and 
to the environments in which the germplasm was grown.

Oikeh adds that maize was chosen for the project because per capita consumption 
of the crop in western Africa is 66 to 216 pounds a year. Maize kernels there 
are processed into pastes, gruels, and porridge. Green maize serves as an 
important vegetable crop to bridge a "hunger gap" that occurs each year after 
the long dry season. It is eaten boiled or roasted on the cob.

Most of the region's rural population relies on cereal- and legume-based diets 
as their major sources of essential micronutrients.

IITA is an independent organization that conducts research, germplasm 
conservation, training, and information-exchange activities in partnerships with 
regional bodies in sub-Saharan Africa. It employs about 80 scientists from more 
than 30 countries. Oikeh says the Nigerian government collaborated with IITA on 
this maize-enhancement project.

A Gathering From Near and Far

IITA grew the maize in three climate- and elevation-distinct regions: Ikenne, a 
forest environment along Nigeria's southern part that is about 180 feet above 
sea level with a yearly rainfall of about 55 inches; Mokwa, in the southern 
Guinean savanna, which is 650 feet above sea level and gets an annual rain total 
of about 47 inches; and Saminaka in the northern Guinean savanna, which is at an 
altitude of 2,000 feet and receives 35 to 47 inches of rain yearly.

Once transported to Ithaca, dried maize samples were ground to uniform fine 
powders and stored at 4 C (39.2 F) before being analyzed in the artificial 
gut. The strategy was to measure both the iron content and the availability of 
the iron.

"Improving maize or any other crop as a source of iron involves improving the 
iron content while maintaining iron bioavailability, improving that 
bioavailability, or better yet, both," says Glahn. Results indicate that the 
selected varieties show promise, but much more work remains.

"A much greater increase in iron bioavailability needs to be developed in these 
lines to ensure nutritional impact," says Glahn. "We also need to monitor the 
stability of the genetic differences over consecutive growing seasons and across 

The next step is a series of artificial gut screening trials coupled with animal 
and human trials to verify the success of the breeding program.

"Biofortification will produce better crops that are acceptable to both farmers 
and consumers," Glahn says. "In this situation, we want to use traditional 
breeding techniques, as they are more acceptable to the consumer, thus 
increasing the likelihood of success. Furthermore, biofortification is a more 
sustainable approach and can be done and maintained for a fraction of the cost 
of other fortification programs."

Glahn adds that similar testing has begun with wheat and rice from other parts 
of the world and that other vegetable and staple crops will be subjected to the 
research as well. - By Luis Pons, Agricultural Research Service Information 

This research is part of Human Nutrition, an ARS National Program (#107) 
described on the World Wide Web at

Raymond P. Glahn is with the USDA-ARS U.S. Plant, Soil, and Nutrition Research 
Laboratory, Tower Rd., Ithaca, NY 14853-2901; phone (607) 255-2452, fax (607) 

"Pumping Iron Into Western Africa's Corn" was published in the April 2003 issue 
of Agricultural Research magazine.