**Abstract**

Maize occupies an important position in the world economy, and serves as an important source of food and feed. Together with rice and wheat, it provides at least 30 percent of the food calories to more than 4.5 billion people in 94 developing countries. Maize production is constrained by a wide range of biotic and abiotic stresses that keep afflicting maize production and productivity causing serious yield losses which bring yield levels below the potential levels. New innovations and trends in the areas of genomics, bioinformatics, and phenomics are enabling breeders with innovative tools, resources and technologies to breed superior resilient cultivars having the ability to resist the vagaries of climate and insect pest attacks. Maize has high nutritional value but is deficient in two amino acids *viz.* Lysine and Tryptophan. The various micronutrients present in maize are not sufficient to meet the nutritive demands of consumers, however the development of maize hybrids and composites with modifying nutritive value have proven to be good to meet the demands of consumers. Quality protein maize (QPM) developed by breeders have higher concentrations of lysine and tryptophan as compared to normal maize. Genetic level improvement has resulted in significant genetic gain, leading to increase in maize yield mainly on farmer's fields. Molecular tools when collaborated with conventional and traditional methodologies help in accelerating these improvement programs and are expected to enhance genetic gains and impact on marginal farmer's field. Genomic tools enable genetic dissections of complex QTL traits and promote an understanding of the physiological basis of key agronomic and stress adaptive and resistance traits. Marker-aided selection and genome-wide selection schemes are being implemented to accelerate genetic gain relating to yield, resilience, and nutritional quality. Efforts are being done worldwide by plant breeders to develop hybrids and composites of maize with high nutritive value to feed the people in future.

**Keywords:** food, maize, molecular breeding, Nutritional security, stress

#### **1. Introduction**

Maize or corn (*Zea mays* L.) belonging to Gramineae family is grown all over the globe as an important annual cereal crop. It is grown as staple food crop in many parts of the world and stands third leading cereal after wheat and rice [1]. Maize is globally called as queen of cereals due to its higher yield potential as compared to rest of the cereals. USA stands first in maize production which alone contributes about 35% of the world's total maize production. In India, the highest producer of maize is Uttar Pradesh, however it is grown in almost all the states in India. U.P, Bihar, Rajasthan, M.P, Punjab, Haryana, Maharashtra, Andhra Pradesh, H.P, W.B, Karnataka, and Jammu and Kashmir are major maize producing states, jointly accounting for over 95% of the national maize production [2]. For animal feed, maize is commonly used. It is commonly processed into different product categories, such as cornmeal, grits, starch, pasta, tortillas, snacks, and cereals for breakfast. Flour of maize is used to make chapatis or flat breads that used to be common dishes in a few northern states of India [3]. The phytochemical compounds obtained from maize and their health properties have recently become the main focus of studies due to increasing attention to the development of nutraceuticals. Maize a monoecious plant has differently located male and female flowers. Tassel is the male flower, and silk is the female flower. Tassel develops 2–5 days before silk that makes it protandrous in nature. The cultivated maize has six different types with each one having different characteristics and specific use, (i) Dent corn: Mostly grown in USA, called as soft maize, (ii) Flint corn: Also called hard corn and is mostly grown in India, (iii) Sweet corn: sweet in taste due to both starch and sugar present in it. It is harvest green and fetch fresh to the market, (iv) Pop corn: most popular type of corn for consumption purpose in humans. It has small sized grains with hard endosperm, (v) Flour corn: the starch present in this type is very soft and the corn shrinks on ripening (vi) Waxy corn: this corn has a soft wax-like substance which resembles tapioca starch.

Maize for livestock feed is important both as residue of crops and silage, grain and is used for extraction of oil and starch industrially. The biological value of maize reflects that it is rich source of carbohydrate, protein, iron, vitamin B, and minerals. The fresh green cobs are eaten separately as roasted or boiled or mixed with legumes. The maize plant has economic value in its every part like the grain, leaves, stalk, tassel, and cob to produce different varieties of food and non-food products.

#### **2. Maize: a potential nutritious cerealcrop**

The nutrient status of kernels in maize depends on the genotype or genetic background, management of agronomic practices, genotype-environment interaction and handling after the harvest of produce [4]. Most of the micronutrients present in widely used maize are not sufficient enough to meet nutritional demand of consumers, however the concentration of different micronutrients can be increased by developing cultivars with improved neutraceticals due to higher degrees of genetic variations in maize. This process is called biofortification [5]. Additional or complementary crop management and food science innovations may also help to enhance the nutritional effect of diets based on maize [6]. Maize researchers have developed improved nutritionally useful cultivars such as quality protein maize (QPM) rich in lysine and tryprophan [7], biofortified orange maize with provitamin-A carotenoids [8] and high-Zn-enhanced maize [9]. Through conventional breeding, higher levels of lysine and tryptophan, kernel Zn and provitamin- A have been successfully increased in maize. Due to various factors, including the availability of large genetic diversity for the target characteristics, advances in understanding key biochemical pathways for metabolite biosynthesis, analytical tools for screening germplasm for quality characteristics, and the possibilities for understanding key biochemical pathways for metabolite biosynthesis, there are now significant

opportunities for more effective development of nutritionally enriched cultivars of both grain and specialty maize [10].
