www.checkbiotech.org ; www.raupp.info ; www.czu.cz

The HarvestPlus Maize group examines progress toward breeding maize with
enhanced, pro-vitamins A, iron, and zinc, November 2005 by Kevin Pixley.

CIMMYT maize scientists and colleagues from national programs in the key
countries targeted by HarvestPlus reported significant progress in
identifying maize with elevated concentrations of iron, zinc, and
pro-vitamins A (chemicals the human body can convert to vitamin A) in their
elite maize varieties and germplasm collections. The results of two years of
work were presented at the second HarvestPlus Maize meeting hosted by
EMBRAPA, the national agricultural research program of Brazil at their maize
and sorghum research station in Sete Lagoas.

Maize is a key target crop for nutritional enhancement because it is so
widely consumed in areas where high malnutrition?especially vitamin-A
deficiency?exists. Scientists working in the HarvestPlus program hope
eventually to breed high-quality, high-yielding maize with enhanced
pro-vitamins A, iron, and zinc content. These micronutrients in maize will
have to be in a form that survives processing and can be utilized by the
human body.

The first planning meeting for the maize scientists was held in 2003 in
Ethiopia. ?We?ve come a long way since we first met two years ago,? says
Kevin Pixley, the HarvestPlus Maize coordinator and Director of CIMMYT?s
Tropical Ecosystems Program. ?But we have also realized that this is a very
complex subject with many assumptions that have to be validated.?

CIMMYT maize breeder Dave Beck (left) examines EMBRAPA maize during a field
visit.

CIMMYT maize breeder Dave Beck showed the group results of screening of
CIMMYT elite highland and transition zone maize germplasm for enhanced
levels of pro-vitamins A, zinc, and iron. HarvestPlus nutritionists have set
minimum targets for the concentrations of these micronutrients in maize. The
good news is that for zinc, CIMMYT has identified material that was already
above the threshold. For iron the picture is less promising as existing
lines identified have only 60 percent of the required minimum level for
iron. For pro-vitamins A CIMMYT has examined hundreds of lines. The best
CIMMYT lines have about 75 percent of the minimum requirement, but sources
identified by project partners in the USA have the minimum required level of
pro-vitamins A. The CIMMYT team is now breeding to enhance pro-vitamins A
concentration for highland, transition zone, mid-altitude, and
lowland-adapted materials.

A topic of keen interest at the meeting was how to convince people to adopt
any nutritionally enhanced maize varieties that might be developed. In much
of eastern and southern Africa, white maize is preferred over yellow maize.
Scientists in Zambia and Zimbabwe had conducted studies about the
acceptability of yellow maize. Both studies found that yellow maize is
associated with food aid and that was one reason people did not want to eat
it. Scientists know there is a strong correlation between the color of the
maize and the total level of carotenoids. Some of these carotenoids are
precursors for vitamin A ?pro-vitamins A.? Torbert Rocheford, a professor of
plant genetics at the University of Illinois, suggested that the debate
should not actually be about yellow maize in many parts of Africa. He said
what we should be talking about is orange maize?something new that will not
carry the stigma of yellow maize but will have high pro-vitamins A content.

[www.cimmyt.org]

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