Marker-Assisted Breeding for Abiotic Stress Tolerance in Crop Plants

Abstract

Maize (Zea mays L.) is an important food and feed crop of the world. Together with rice and wheat, it provides around 40% of the food calories to more than 4.5 billion people in 94 developing countries. It also provides nearly 50% of the dietary protein for humans. In Africa and some of the Asian countries, almost 90% of maize grown is for human consumption and may account for 80–90% of the energy intake. In India, it is the third most important food crop after rice and wheat, both in terms of area and production. India is the fifth largest producer of maize in the world contributing 3% of the total global production. Protein malnutrition is widespread in the developing and underdeveloped countries, where 780 million people are affected by the same. Maize is the leading cereal in terms of production and accounts for 15% of proteins and 20% of calories requirement of the world. Protein malnutrition is caused by lack of access to adequate quantity and better quality protein intake and usually affects children and elderly persons. Maize, however, lacks adequate amounts of the essential amino acids, namely, lysine and tryptophan. Decades of efforts by maize researchers lead to the development of nutritionally superior maize cultivar popularly called as quality protein maize (QPM), which has twice the amount of lysine and tryptophan, thus making its quality as good as casein of milk. The o2 allele along with modifiers for tryptophan and lysine content and grain hardness made QPM agronomically suitable for cultivations. Intensive efforts were made by many workers to understand the genetics, molecular mechanism of QPM modifiers and applied these genomics knowledge to developed MAS-based QPM inbreds and commercial hybrids. All those studies and concerted efforts led to development and utilization of QPM. The area under QPM globally is more than 9.0 million hectares. Several reports were available on positive impact of QPM on children and adults. It has also been demonstrated in poultry and piggery, resulting in increased egg production and egg quality parameters and body mass. The area under QPM and consumption of QPM can be increased significantly by providing policy supports for QPM.