Breeding Challenges and Perspectives in Developing and Promoting Quality Protein Maize Germplasm



The chapter discusses the development of nutritionally enhanced maize popularly known as quality protein maize (QPM). The focus will be on describing ever-evolving breeding options and strategies in developing this maize. Most of the examples will be quoted from CIMMYT’s work where much of the research and practical breeding has been attempted. Initially, approaches of CIMMYT breeders were not very different from other researchers. High-lysine mutants such as opaque-2, floury-2, opaque-7, and a few double mutant combinations of different endosperm mutants were tried. Experiences, difficulties, and manipulation of different mutants will be presented having relevance to the development of high-lysine maize genotypes. The strengths and weaknesses of early breeding efforts will be critically discussed revealing complexity of interrelated problems affecting acceptance at producer, consumer, and industrial processing level. Initial research efforts at CIMMYT and elsewhere were confined to developing soft endosperm opaque versions of counterpart normal maize varieties and hybrids. Extensive testing of such materials exposed a series of problems of poor agronomic performance, unacceptable kernel appearance, and some problems of specific nature under certain environmental conditions. High hopes and early optimism of mid-1960s and early 1970s received a major setback in research efforts and brought lots of frustration and declining interest in high-lysine maize types. Funding declined resulting in reduced breeding efforts and abandoning of research partially or completely in several parts of the world. Only a handful of institutions and breeding programs continued research in a persistent and a systematic manner. Continuing efforts demanded exploring other options with and without high-lysine mutants. Several approaches were tried and critically examined for their merits and demerits. Different approaches were selected and emphasized in different institutions. These will be briefly discussed, but emphasis will be given as to why these approaches failed to produce desired results. CIMMYT’s approach has proven to be viable and has been successfully tried in programs still maintaining interest in this particular maize. Selection of appropriate strategy(ies) and breeding method(s) was the key to CIMMYT’s success. One-shot strategy as opposed to several individual problem-related strategies was a must. Based on experience and available information, the choice was to use a combination of two genetic systems involving the opaque-2 gene and genetic modifiers of the opaque-2 locus. At the very outset, there was a hope that this system can resolve complexity of problems plaguing such materials. A series of steps were practiced to implement this strategy and to start using it on a larger scale. Variation in kernel modification had to be encountered and donor stocks had to be built up initially. Some chance events will be mentioned which greatly facilitated rapid development of QPM donor stocks. The next challenge was to develop QPM germplasm adapted to different ecologies. A wide array of breeding approaches was used to accomplish this needed task. These will be fully discussed as to their relevance then and now.

Huge QPM germplasm volume was built through these varied efforts. By mid- to late 1970s, improvement of QPM populations through international testing had already begun. Germplasm merging process was initiated at this stage to form manageable number of QPM populations and pools so that systematic improvement process could be started. At this point, an important decision was also made to work in homozygous opaque-2 backgrounds. The next turning point in QPM breeding efforts was in mid-1980s when hybrid development was started. Combining ability information and heterotic patterns of important classes of QPM germplasm were established. Other aspects of hybrid development such as inbred development, hybrid formation, and testing were initiated on a modest scale. Even with a few hybrids formed and tested, the results were quite encouraging. Several QPM hybrids had performance levels quite similar or superior to better performing normal hybrids. The past 15 years or so have witnessed much greater emphasis on QPM hybrid formation and testing at CIMMYT. The international testing of QPM hybrids has substantially increased, and many national programs are finding these hybrids quite satisfactory in performance to the available commercial hybrids. Several countries have released hybrids while others are on the verge of releasing soon. Future strategies as well as traditional and modern methodologies and tools that need to put in place will be discussed to have broader QPM germplasm base available worldwide for breeding efforts. One point, at the end, which I want to highlight is that support from biochemical laboratory was an important factor for the success of QPM work at CIMMYT. I consider QPM research as an excellent example of interdisciplinary team effort at CIMMYT where biochemists and breeders have worked in complete coordination to produce desired and acceptable QPM products.


Genetic Modifier Modify Kernel Quality Protein Maize Hybrid Development Hard Endosperm 


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© Springer India 2014

Authors and Affiliations

  1. 1.CIMMYTTexcocoMexico

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