New Maize for a New Era
In 1963, scientists at Purdue University were studying seemingly commonplace Andean maize races and found something extraordinary. One sample contained a peculiar gene that significantly increased grain levels of lysine and tryptophan, amino acids that are essential building blocks for proteins in humans, poultry, and pigs. Named “opaque-2” because it gave kernels a chalky appearance, the gene also conferred low yields and susceptibility to many pests and diseases.
With
support from the United Nations Development Programme (UNDP), during the
1970-80s CIMMYT used conventional field and lab techniques to overcome
opaque-2’s drawbacks, developing a new product named “quality
protein maize” (QPM). The new maize looks, grows, and tastes like
normal maize, but contains nearly double the lysine and tryptophan and
a generally more balanced amino acid content that makes it more nutritious.
It is intended for the very poor who depend heavily on maize and lack
access to meat, legumes, or other sources of protein, and has also shown
potential as an ingredient in feeds for pigs and poultry. CIMMYT maize
breeder Surinder K. Vasal and cereal chemist Evangelina Villegas shared
the 2000 World Food Prize for their efforts to create QPM. In the last
decade, with funding from Nippon Foundation, CIMMYT has worked with partners
to develop and promote QPM, varieties of which have been released to farmers
in 25 developing countries (see map).
The Limitations of QPM
One drawback of the QPM trait is than it is recessive—it is expressed only when both parents contribute alleles. One way to ensure this is by using QPM hybrids and purchasing fresh seed to sow each season. However, many small-scale maize farmers in developing countries use open pollinated varieties and save their own seed for sowing. Such farmers need to observe management practices that avoid out-crossing and maintain varietal purity—these include sowing QPM plots far from other maize, or selecting ears for QPM seed from the center of the plot. Finally, the key attribute of QPM—that it looks, grows, and tastes like normal maize—also makes it difficult to ascertain the presence of the quality protein trait, short of lab testing.
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January, 2005