Quality protein maize: QPM

Abstract

Quality protein maize (QPM) contains the opaque-2 gene along with numerous modifiers for kernel hardness. Therefore, QPM is maize with high nutritive value of endosperm protein, with substantially higher content of two essential amino acids - lysine and tryptophan, and with good agronomical performances. Although QPM was developed primarily for utilization in the regions where, because of poverty, maize is the main staple food, it has many advantages for production and consumption in other parts of the world, too. QPM can be used for production of conventional and new animal feed, as well as for human nurture. As the rate of animal weight gain is doubled with QPM and portion viability is better, a part of normal maize production could be available for other purposes, such as, for example, ethanol production. Thus, breeding QPM is set as a challenge to produce high quality protein maize with high yield and other important agronomical traits, especially with today's food and feed demands and significance of energy crisis

Genetic basis and the current breeding efforts for quality protein maize in Southern Africa

“…The challenges of the opaque-2 maize were, however, short-lived. Researchers at the International Maize and Wheat Improvement Center (CIMMYT) developed hard endosperm opaque-2 genotypes by introgressing endosperm modifier loci (Ignjatovic'-Mic'ic et al, 2008). These transformed the soft and starchy endosperm to a vitreous one that is favoured by farmers, with the retention of elevated levels of lysine and tryptophan.…”

“…In the normal maize endosperm, Hallauer (2001) described the average proportions of the distinct fractions of protein as albumins 3% (water soluble), globulins 3% (salt soluble), zeins or prolamine 60% (alcohol soluble), and glutelins 34% (dilute alkali soluble). Since the zein or prolamine fraction of the endosperm protein is the largest, and it comprises alpha (α), beta (β), gamma (γ) and delta (δ) zeins, it makes them most abundant proteins and comprise 60-80% of total proteins (Ignjatovic'-Mic'ic et al, 2008). The zeins are the most abundant proteins and comprise 80% of total proteins (Ignjatovic'-Mic'ic et al, 2008).…”

“…Since the zein or prolamine fraction of the endosperm protein is the largest, and it comprises alpha (α), beta (β), gamma (γ) and delta (δ) zeins, it makes them most abundant proteins and comprise 60-80% of total proteins (Ignjatovic'-Mic'ic et al, 2008). The zeins are the most abundant proteins and comprise 80% of total proteins (Ignjatovic'-Mic'ic et al, 2008). Generally, the zeins contain high levels of glutamine, proline, and leucine; but are highly deficient in lysine and tryptophan (Balconi et al, 2007).…”

Potential for quality protein maize for reducing proteinenergy undernutrition in maize dependent Sub-Saharan African countries: A review

“…Non-QPM varieties have an average of about 2% lysine and 0.4% tryptophan; whereas lysine and tryptophan levels in QPM average about 4 and 0.8% of the total protein content, respectively (Prasanna et al, 2001;Krivanek et al, 2007;Ignjatoviae-Miciae et al, 2008;Kiria et al, 2010). QPM constitutes 80% of the biological value of cow milk, compared to 45% of non-QPM (Machida et al, 2014;Rajendran et al, 2014).…”

Evaluation of Quality Protein Maize (Zea mays L) Hybrids at Jimma, Western-Ethiopia

“…The trait was found to be closely associated with several undesirable ones. The Opaque-2 maize kernels were dull and chalky, had 15-20% less grain weight and were more susceptible to several diseases and insects [8] leading to the loss of interest towards it among scientists. Fortunate enough, few international researchers had continued their systematic research activities on refining the original Opaque-2 variety with the aim of maintaining its nutritional quality while making it competitive with conventional varieties of improved maize.…”