Nutritionally Enhanced Maize and its Importance in the Developing Countries
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Date
2013
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Badan Penelitian dan Pengembangan Pertanian
Abstract
Improving nutritional quality of cereals is a noble goal as it benefits hundreds of millions of producers
and consumers directly without changing their food habit. Research experience on most crops so far has been
disappointing and the success stories limited.In maize, the situation is different as CIMMYT researchers were able
to exploit high lysine mutants successfully to develop nutritionally enhanced maize now referred to as Quality Protein
Maize (QPM). Maize being a leading crop, contributes significantly to the world’s food basket of roughly 2000 million
tons every year. Unfortunately, maize has high prolamine content, and is deficient in essential amino acids lysine and
tryptophan, thus making it poor in nutritional quality. Biochemists had demonstrated this fact almost hundred years
ago.The discovery of high lysine mutants, opaque-2 and floury -2 by Purdue group in mid-sixties spurred enthusiasm
and hope to elevate levels of lysine and tryptophan to almost double over what is encountered in normal
maize.Conversion programs were initiated worldwide to obtain original soft opaque-2 versions of normal counterpart
varieties and hybrids. Testing of such materials exposed a series of problems including poor agronomic performance
in yield, unacceptable kernel texture, slower drying following physiological maturity and more vulnerable to ear rots
and stored grain pests. As a result pessimism started growing, funding kept on declining and many institutions either
completely abandoned their research work or reduced it substantially. Only in a few institutions, momentum continued
as usual. Exploratory research on many different approaches was tried at CIMMYT to find a single approach or
strategy that will overcome negative association of Opaque-2 gene with other undesirable traits. A combined
approach of two genetic systems involving opaque-2 gene and genetic modifiers of opaque-2 locus appeared to be
a viable approach. Chance events and a few other factors further enhanced confidence in this approach. A huge
volume of QPM germplasm were developed which had a competitive yield performance, acceptable kernel phenotype
and free from other undesirable effects.Over the past two decades or so many countries have released QPM
varieties and synthetics and the trend now is to release hybrids. Some countries in recent years have released QPM
single cross hybrids. Efforts are underway to develop super QPM combining high –oil and some micronutrients such
as Fe, Zinc and pro-vitamin A. It is important to mention that maize is a gifted crop and has many competitive
technologies which can as well be deployed in QPM research. QPM will certainly play an important role in human
nutrition and to correct prevailing problems of Kwashiorkor and pellagra in some developing counties where maize
is a staple food. Projected future needs for livestock and use of maize as feed holds a bright future for QPM from the
standpoint of better feed ratio and reduced use of high priced supplements. These developments pose numerous
challenges for future QPM research.