eChapters

Introduction
Maize (Zea mays L.) is the second most widely crop grown globally after wheat, with 205 million hectares under cultivation. The area cultivated under maize is steadily increasing and expected to overtake that of wheat by 2030 (Erenstein et al., 2022). With production exceeding 1.2 billion metric tons, maize surpasses the production of other highly cultivated cereals like wheat and rice mainly due to its higher yields (Erenstein et al., 2022). Maize is cultivated in the Americas, Africa, and Asia, for multiple end-uses (Nuss and Tanumihardjo, 2010). It is a staple food in several countries across Africa and Latin America, and in a few countries in Asia, with an overall contribution of 15-20% of daily calorific needs (Shiferaw et al., 2011).
The global maize yield tripled from the 1960s with the average yield rising from 2 tons/ha to the current 5.8 tons/ha, mainly due to the adoption of highyielding hybrid cultivars and complementary input use (Erenstein et al., 2022). Maize is naturally an outcrossing species and inbreeding is unnatural. When maize is subjected to inbreeding and the resulting inbred lines from genetically distant backgrounds are crossed, hybrid vigor or heterosis is realized (Springer and Stupar, 2007). Hence, the development of the homozygous inbred lines is a very important step in hybrid maize breeding.
In the well-evolved maize breeding programs, the germplasm is well characterized into different heterotic groups where the hybrids developed by crossing inbred lines from different heterotic groups exhibit high heterosis (Ertiro et al., 2017a; Sang et al., 2022). For the development of inbred lines, maize breeders develop F1 populations by crossing two inbred lines within the same heterotic group (Prigge et al., 2011; Sang et al., 2022). Inbred lines are developed from the F1 population by recurrent self-pollination for 6-8 generations; this can take up to 3-4 years or even more, depending on the availability of off-season nurseries for generation advancement. The resulting inbred lines are highly homozygous (~98-99%), but not 100% homozygous. The doubled haploid (DH) technology emerged as a viable alternative to the time-consuming and resourceintensive recurrent selfing method to produce 100% homozygous inbred lines in just two crop seasons (Prasanna et al., 2012; Chaikam et al., 2019a).
In addition to significantly reducing the time taken to develop homozygous lines, the use of DH lines in maize breeding offers several other benefits: a) As DH lines are completely homozygous at all loci, they are stable and do not show further inbreeding depression; b) DH lines are also best suited for evaluating distinctness, uniformity and stability (DUS) criteria, thereby better facilitating plant variety registration and intellectual property protection (Röber et al., 2005); c) The use of DH lines facilitates selections on completely homozygous lines which is more reliable and effective compared to selections on segregating families with different levels of heterozygosity (Chaikam et al., 2019a); d) Use of DH lines also simplifies breeding operations like planting, managing the nurseries, seed shipments, record keeping, etc. as selfing nurseries spread over several generations are replaced by just two generations for DH line development (Prasanna, 2012; Röber et al.,

Introduction
The process of culturing plant cells, tissues, organs and protoplast on artificial media under controlled and aseptic circumstances is known as ‘Plant Tissue Culture’. It is predicated on the idea of “Cellular totipotency”, which describes a cell’s capacity to develop into a whole plant in the right cultural environment. This characteristic of cells has broad applications in the manipulation of plant cells to enable fast plant multiplication and the in-vitro regeneration of whole plants following the genetic transformation. Around a century ago, the idea of tissue culture was first put forth, to grow entire plants in vitro from somatic cells (Haberlandt, 1902). The tissue culture system has advanced with the identification of different concentration, ratios of auxin and cytokinin, which are critical for the regeneration of adventitious roots and shoots (Skoog and Miller, 1957). Appropriate explant, or plant organ removed, including cotyledons, leaves, roots, shoot apices, nodal segments, hypocotyls, anthers, embryos, and seeds. The explants are thoroughly cleaned with sterile double-distilled water, surface sterilized with a disinfectant such as sodium hypochlorite or mercuric chloride and aseptically cultured in an artificial medium in test tubes/ flasks, jars, and Petri dishes. Several factors influence a plant’s capacity to regenerate, such as the presence of a plant growth regulator (Gerdakaneh et al., 2020), the explant type (Dhar and Joshi, 2005) and the basic medium’s composition (Sundararajan et al., 2017).
The most widely used media include major elements, carbohydrates, growth regulators (auxins, cytokinins etc.), microelements, vitamins, amino acids and several media compositions have been created specifically for plant tissue culture (Atkinson et al. 2012). While 2,4-dichloro phenoxy acetic acid (2,4-D) at concentrations of 0.5-4.0 mg/L typically induces callus, or a homogeneous mass of undifferentiated cells, auxins at concentrations ranging from 0.1 to 5.0 mg/L, favour rooting by cell elongation. Similarly, cytokinin’s induce fast cell division and the growth of shoot buds/shoots. Agaragar, agarose, and GelriteTM are examples of chemically inert, powdered gelling agents added to the culture medium to solidify it before it is autoclaved. After the medium has been added to the culture containers, they are autoclaved. Explants in the culture vessels are injected under aseptic circumstances in a laminar air-flow cabinet equipped with high-efficiency particulate air (HEPA) filters (pore size 0.2–0.3 mm). Explants that are placed in the right growth medium under the right circumstances dedifferentiate, or mature cells that have increased DNA/ RNA and protein production return to their meristematic state. Regrowth in the agar-gelled medium results in an amorphous mass of cells known as ‘callus’. Suspension culture, a method of cultivating cells in a liquid medium, produces a suspension of individual cells. Every three to four weeks, the developing tissue must be sub-cultured onto a new medium because an increase in cells or calli causes the medium to run out. In the end, the organogenesis pathway is utilized to create ordered structures like roots, branches, flower buds, etc. from these cells and tissues. The synthesis, preservation, and application of

Introduction
Vegetables are an essential diet component for human beings and nutritional security because of their short season, high yielding potential, nutritional capacity financial viability and potential to create on-farm and off-farm agricultural employment. India ranks as the world’s second-largest producer of fruits and vegetables. In India, vegetables and fruits accounts for about 92% of the total horticultural production. Daily diet consisting of vegetables is primary sources of proteins, vitamins, minerals, dietary fibers, micronutrients, antioxidants and phytochemicals. Additionally, vegetables have wide range of phyto-chemicals such as anti-carcinogenic factors and anti-oxidants constituents (e.g. flavonoids, glucosinolates and isothyocynates) (Silva Dias, 2019). In India an area of 11.35 million hectares is employed for the production of vegetables which is around 204.84 million metric tonnes (APEDA, 2023). Novel genotypes adaptable to various horticultural systems must be developed due to rapid climate change, customers demand and the resurgence and emergence of plant’s pest and diseases (Cardi et al., 2017). Plant tissue culture is emerging as a technology which has significant impact on agriculture sector by producing plants to meet out the growing global demand. It provides the huge potential areas currently offering a glimpse into the future. Apart from this, it has advanced significantly in the area of vegetable sector. Vegetable crops can be improved through efficient in vitro plant regeneration system of biotechnological approach consisting of meristem culture, haploid production and somatic hybridization (Kumari et al., 2020). Genetic engineering is a novel approach to produce improved crops varieties with greater yield potential and pest resistant. Genetic transformation plays an important role in genetic engineering process in order to improve genetics of crop plants. The world’s demand for nutritious and cheap food market have prompted the scientists to step up their efforts to genetically modify the economically significant plants. Traditional breeding methods have several limitations such as more time consuming to develop a plant with desired traits and sexual incompatibility barrier and these limitations can be overcome by adopting effective strategies for regeneration and transformation of valuable plants. Genetic engineering has shown to be an excellent method for improving vegetable crops under different adverse conditions (Gerszberg, 2018). Plant tissue culture and molecular biology are the technical foundations of genetic transformation technology, which is used to produce enhanced crop varieties, disease-free plants (virus-free), genetic transformation, secondary metabolite production, and varieties resistant to various biotic stresses such as diseases-pests, and abiotic stresses like high temperature, drought, and salinity (Hussain et al., 2012).

Introduction
A plant seed consists of an embryo and reserve food material (endosperm/ cotyledon) which is surrounded by a protective seed coat. The seed ensures that the next generation of plants exists. The embryo is made up of one or two cotyledons attached to a central axis. The upper part of the axis contains a plumule at its tip. The plumule grows into the shoot system. The lower part of the axis consists of the hypocotyl and a radicle. The radicle grows into the root system. The endosperm is the food reserve that the embryo uses during the early stages of germination. Before the embryo is able to produce its own food through photosynthesis, the endosperm provides vital nutrients to the embryo. Seed stands as an essential and fundamental agricultural input. It can be characterized as a propagative entity that facilitates the continuation of species from one generation to the next. Alternatively, it can be described as a mature fertilized ovule. Seeds play multifaceted roles for their parent plants, encompassing embryo nourishment, dispersion to novel locations, and entering a state of dormancy during adverse environmental circumstances. Seeds originate from various sources like self-pollination, cross-pollination, vegetative propagation, and mechanisms such as apomixis, resulting in diverse varieties or hybrids. Maintaining the genetic consistency of cross-pollinated seeds presents notable challenges. Certain fruit crops encounter obstacles in natural seed propagation due to factors like seed heterozygosity, diminished endosperm size, or minuscule seed dimensions. Additionally, some seedless fruits cannot be propagated conventionally through seeds. Seeds frequently become susceptible to seed-transmitted diseases, facilitating the transmission of diseases across different geographical areas. These constraints in seed-based propagation have spurred the exploration of alternative techniques for species proliferation. This exploration led to the emergence of the concept of synthetic seeds within the realm of plant tissue culture. Synthetic seeds are also known as synseeds or artificial seeds or somatic seeds, seed analog, or manufactured seed. The concept of synthetic seeds has been described in various manners by different researchers. Capuano et al., (1998) defined synthetic seeds as somatic embryos that are enclosed artificially, originating from shoot buds, cell aggregates, or any suitable plant tissue for sowing purposes. These synthetic seeds are capable of developing into plants under controlled in vitro or ex vitro conditions and can maintain this potential even after prolonged storage. Another definition of synthetic or artificial seeds comes from Gray and Purohit (1991) and Redenbaugh (1993), who refer to them as somatic embryos designed for use in the commercial propagation of plants.

Nutritional significance of millets
Millets, nutrient-dense grains rich in proteins, vitamins, minerals, and dietary fibre, are emerging as vital components of a balanced diet, particularly in regions where they serve as staple foods. Their high content of essential amino acids, iron, calcium, zinc, and B vitamins makes them crucial for addressing micronutrient deficiencies (Hassan, 2021). As gluten-free grains, millets are suitable for individuals with celiac disease or gluten intolerance, broadening their dietary appeal. Additionally, millets are rich in health-beneficial phenolic compounds, making them suitable for food and feed. Finger millet, with its diverse phenolic profile, has higher antioxidant activity than pearl millet. These phytochemicals positively impact human health by lowering cholesterol and phytates. Incorporating millets into human and livestock diets can improve health, reduce disease risks, and ease the pressure on maize (Hassan, 2021).
Essential nutrients in millets
Millets are particularly rich in carbohydrates, providing a sustained energy source essential for daily activities. Unlike refined grains, millets have a low glycaemic index, releasing glucose slowly into the bloodstream. This characteristic helps manage blood sugar levels and prevents spikes, making millets an excellent food choice for individuals with diabetes. Numerous studies have demonstrated that regular millet consumption can offer a variety of health benefits. The high fiber content in millets supports digestion, prevents constipation, and promotes a healthy gut microbiome (Jacob, 2024) Consuming millets can lower the risk of chronic diseases such as cardiovascular disease, type 2 diabetes, and certain cancers. The antioxidants present in millets protect against oxidative stress and inflammation, which are key contributors to many health conditions. Furthermore, millets high fibre content and low glycaemic index promote feelings of fullness, regulate blood sugar levels, and help maintain a healthy body weight. Millets are ancient small grains grown in arid and semi-arid regions of the world, serving as staple foods for many people in Asia and Africa. Abundant sources of minerals and vitamins, they are often referred to as Nutri cereals. Millets contain valuable phytochemicals that provide therapeutic properties for various disorders and diseases, giving them nutraceutical value. (Mishra, 2022)
A wide array of biochemical compounds is present in the plant parts and grains. In the oldest texts of medicine in India and China, millets are noted for their medicinal value. Expanding interest and emerging facts highlight their therapeutic uses, with ample evidence showing that millet consumption aids in correcting lifestyle and metabolic disorders. The therapeutic properties of millets can be viewed in two ways: supplementary nutrition through minerals and vitamins, and therapeutic value through phytochemicals and specialty compounds like flavonoids, phenolics, and anthocyanidins that have antioxidant potential (Chellappan 2024). Millets are gluten-free, have a low glycaemic index, and their phytochemicals help correct lifestyle disorders and prevent ailments such as carcinogenesis. Supplementary benefits include the treatment of anaemia and

Introduction
World food security has become largely dependent only on a handful of crops like; wheat, rice, and corn which are the major cereals that support more than 50% of the global calorie demand. While these grains are an essential part of various diets, however they are devoid of essential micronutrients. As a result, it is estimated that micronutrient deficiency affects an estimated 2 billion people worldwide raising health concerns over our high dependence on cereal crops. As agriculture sector is considered as backbone of nation and therefore utilizing a handful of crops have placed the global food security at risk. In this context, Food and Agriculture Organization (FAO) has identified many plants as under-utilized, which can significantly contribute for improving nutrition and health, enhance food basket and livelihoods, future food security and sustainable development (FAOSTAT, 2023). These underutilized crops offer an immense potential in the functional food sector to combat hidden hunger crisis and offer the options of income generation.
Cereals such as rice, maize and wheat are monocots and belong to family Poaceae, however buckwheat, chia, quinoa and amaranthus although resembles with cereals are dicots and are categorized as Pseudocereals. These crops have been placed under the category of important crops by UNESCO due to dwindling cultivation and exploitation in the wild besides, these pseudocereals has gained a worldwide importance in the nutraceutical industry due to the rich nutritional profile compared to cereals and are considered as crops of the 21st century (Pirzadah et al., 2020). These are enriched with various active principals such as; polyphenols, flavonoids, amino acids, dietary fibre, lignans, vitamins, minerals, antioxidants, unsaturated fatty acids and other essential components like fagopyritols. The protein quality and quantity in pseudocereals is far better compared to cereals and this property qualifies their entry into the functional food industry (Rodriguez et al., 2020). Pseudocereals are rich in amino acids such as; arginine, tryptophan, lysine and histidine that proved essential for infant and child health thus, projected pseudocereals as an appropriate food supplement for child nutrition. The food production agro-systems must be adapted to climate change to ensure food security and stability. However, pseudocereals are climate resilient crops and can be grown even on marginal lands that are not fit for cereals thus, are considered as future crops to tackle mal-nutrition and future food crises. To explore these neglected or lost crops, there is an increasing interest in research and development that needs heightened direction and focus (Mabhaudhi et al., 2019). In this context, there is a need to adopt recent biotechnological interventions for the crop improvement and domestication of pseudocereal crops. This chapter focuses on nutritional profile of emerging pseudocereals viz., Buckwheat, Chia, Quinoa and Grain amaranth, phylogeny, genetic resources, breeding behavior and advanced breeding methods and their integration into the global food system

Introduction
In recent years, there has been a growing interest in alternative nutritious food sources (McClements, 2020) and such group of foods that has gained significant attention is millets. Millets are a diverse group of small-seeded grasses that have been cultivated and consumed for thousands of years. They are rich in essential nutrients such as proteins, fibers, vitamins, and minerals, making them an important addition to a balanced diet. Millets are not only rich in essential nutrients but also have several health benefits. They are known to have nutraceutical properties, low glycemic index, making them suitable for individuals with diabetes. Additionally, millets are a good source of antioxidants, which can help in reducing the risk of chronic diseases such as heart disease and cancer. The diverse range of millet varieties also provides flexibility in incorporating them into various dishes, making them suitable for different culinary preferences and dietary requirements. Therefore, the usage of millets can play a crucial role in promoting sustainable and healthy eating habits.
Malnutrition continues to be a pressing issue worldwide, particularly in developing countries (Ashok et al., 2020). The lack of access to nutritious food is one of the main causes of malnutrition, leading to various health problems such as obesity, diabetes, cardiovascular diseases, cancer, and celiac disease (Birania et al., 2020). To address this issue, millets have emerged as a promising solution. Despite being nutritionally superior to other cereals, millets have traditionally been limited to consumption by the poor and those with conventional dietary practices. However, there is a growing recognition of the potential of millets in combating malnutrition and improving public health. Millets, such as finger millet, pearl millet, and sorghum, are often referred to as “superfoods” due to their high nutritional content (Singh et al., 2020). These grains are rich in protein, carbohydrates, fats, vitamins, minerals, and dietary fiber, making them an ideal source of essential nutrients (Ashok et al., 2020). Additionally, millets are easily available and costeffective, making them a viable option for addressing malnutrition on a larger scale (Birania et al., 2020). Furthermore, millets are resilient crops that can withstand environmental changes and water shortages, making them an ideal choice for sustainable agriculture. In this chapter, we delve deeper into specific aspects of millet nutrition, examining their micronutrient profiles, health benefits, culinary versatility, and potential applications in combating malnutrition and promoting sustainable agriculture. By understanding the nutritional richness of millets, we can uncover innovative solutions for improving human health and fostering agricultural resilience.

Organic Agriculture
Organic and biodynamic farming use natural methods to grow crops, avoiding inorganic fertilizers, pesticides, and other chemicals throughout the growth stages. This approach relies on natural biological systems, preserving their relationships and self-regulation, unlike conventional farming, which heavily depends on synthetic inputs. As a result, plant and animal varieties bred for intensive agriculture often do not align with organic principles. To unlock the full potential of organic farming, genetics of seeds should also be organic, ideally bred and grown exclusively in organic conditions to best suit these systems.
Organic plant breeding
Improving the genetic diversity of the crops and their adaptation to the future organic growing conditions and climate change need to be done through organic plant breeding. The choice of varieties for organic farming that are mostly derived from conventional bred varieties, sustainable use of natural input resources and at the dynamic equilibrium of the entire agro ecosystem are the main features. The organic breeding programs should match with the reproduction system of the respective crop. Seeds and vegetatively propagated crops are important resources for organic breeding. The Organic agriculture system relies on natural inputs and pesticide free and non GMO crops, vegetable and fruits aiming providing healthy food. In an overall manner, organic agriculture is the expression of underlying ecology, fairness and health. Organic agriculture is presently practiced in organically converted and managed land area equal to 2% of the cultivated area in India.
International Federations of Organic Agriculture Movement (IFOAM) (2015 and 2017): Organic agriculture is defined as a production system that sustains the soil health, ecosystem and people. It relies on ecological processes, bio diversity, and local conditions. Organic farming is part of organic agriculture and it is basically based on the underlying principles of health, fairness, ecology and care. The well-known characteristic of organic farming is, it produces food without the use of any synthetic fertilizer or pesticides and also without the use of GMO. Trends and perspectives in organic plant breeding are recognized as a highly collaborative and possess strong interrelationships.

Introduction
The increase in the world population coupled with climatic fluctuations such as drought, floods, and high temperatures poses a serious threat to food security (Ray et al., 2013). Many researchers have quoted the importance of enhancing the genetic gain of primary crops at a faster rate to meet global food demands (Lin et al., 2016). It remains a challenging task for plant breeders to evolve resilient varieties in a shorter period by employing conventional approaches. The slow progress in crop improvement is mainly attributed to long breeding cycles/generations (Samantara et al., 2022). To overcome the drawbacks involved in traditional methods and to safeguard food security, speed-breeding methods are now being adopted at large or small units to achieve rapid genetic gains in many crop species. The speed breeding techniques include the use of controlled environments with manipulation provisions for light duration, intensity and temperature. This approach is more advantageous for helping plant breeders hasten crop development in several major photosensitive crops (Singh and Janeja, 2021).
Breeding a new crop variety via a conventional approach requires the selection of complementary parental genotypes with desired traits, followed by crosses and a series of selections and advancements of superior progenies to release candidate cultivars that meet market demands (Shimelis and Laing, 2012). Notable breeding goals in crop cultivar development programs include increased yield potential and nutritional quality and enhanced tolerance to biotic and abiotic stresses (Breseghello and Coelho, 2013). In any crop improvement program, the following breeding procedures can be distinguished in the order presented: (a) selection of desirable parents with complementary traits to be combined; (b) crosses involving the selected parents and the development of progenies; (c) selection and genetic advancement of the best progenies based on target traits; (d) selection of the best progenies for screening in multiple target production environments to identify the best performing and stable candidate cultivars; and (e) cultivar registration and seed multiplication and distribution to growers (Shimelis and Laing, 2012). These conventional breeding procedures are used in most crop cultivar improvement

Introduction
Current state of global warming and climate change affecting crops through altered pest and disease incidence patterns, changes in temperature and CO2 levels which adversely affected the crop production (Habib-ur-Rahman et al. 2022). This threat is particularly pronounced in food-insecure regions, especially in Asian countries. Climate change not only jeopardizes crop and livestock health but also impacts soil and water resources and livelihood of rural communities. Furthermore, it contributes to food insecurity by increasing prices and reducing overall food production. The complexity of these effects highlights the need for modern agricultural techniques to mitigate risks and ensure global food security (Habib-ur-Rahman et al. 2018).
Crop improvement, an integral facet of agricultural development, remains a cornerstone in addressing the burgeoning global food demands. Conventional plant breeding methods have played a pivotal role in developing improved crop varieties that exhibit enhanced quality, higher yields and resilience to biotic and abiotic stresses. However, plant breeding methods involving continuous selection and intermating among closely related individuals can result in a reduction of genetic diversity within a cultivated crop species. The narrow genetic base makes crops more vulnerable to emerging threats, such as new pests or diseases and limits their ability to cope with changing climatic conditions. In India, the Green Revolution along with substantial plant breeding activities, led to a significant increase in crop yields, particularly in staple crops like wheat, rice and maize. However, one of the major consequences of green revolution is the development of narrow genetic base in cultivated crop species (Begna 2021).
Moreover, the reliance on a narrow genetic base, a consequence of crossing only two parents, curtails the exploration of broader genetic diversity. This limitation restricts the potential for effectively combining and expressing desired traits in the resulting crop varieties. Most of conventional plant breeding techniques were primarily focused on monogenic traits, while many agronomically important traits are quantitative in nature, controlled by polygenes, and influenced by the environment. This poses challenges for breeders relying only on phenotypic selection. Notably, traits influenced by multiple genes, such as resistance to diseases or tolerance to environmental stresses, are particularly challenging to manipulate using traditional breeding methods.
Quantitative trait loci (QTLs) are genomic regions that influence polygenic traits, first described by Geldermann (1975). Identifying QTLs associated with improving yield and quality traits is pivotal for catalysing a new Green Revolution (Arrones et al. 2020; Pradhan et al. 2015). Marker-assisted selection (MAS), introgression breeding and QTL pyramiding offer efficient avenues for developing improved cultivars. However, identifying QTLs associated with quantitative traits remains a challenge for plant breeders (Arrones et al. 2020). The basic requirement for the detection of QTLs involves appropriate mapping population, marker systems, phenotyping methods and suitable experimental designs (Arrones et al. 2020; Collard et al. 2005)

Introduction
The genetic diversity of crops has been subjected to considerable humandriven selection throughout time, in particular, is often limited by conventional plant breeding techniques. Under these conditions, crops with low yields and a high risk of disease and pest infestation may be produced. Thus, there’s a need to introduce a technique where solutions to all the problems can be addressed. CIS breeding opens us a wider range of opportunities for improving crops by enabling the deliberate incorporation of natural genetic differences from closely related plants. The word “CIS” in CIS breeding means “on the same side/same kingdom”. CIS breeding is an advanced method for genetic improvement in which genes from closely related plants are inserted into the desired crop. This method creates crop varieties that are greatly improved in terms of growth capacity, yield potential and pest and disease resistance. CIS breeding is a pioneering technology designed to integrate novel traits into established crop varieties without the introduction of foreign genetic material. Utilizing the similar gene combinations and the plant’s intrinsic genetic systems, it is a natural form of genetic improvement that improves traits including yield, drought resistance, disease resistance and nutritional qualities (Anjanppa and Gruissem, 2021). Comparing to conventional breeding where gene transfer can occur through random cross- breeding or mutagenesis and risk of unintended effects are high, in CIS breeding, one or few genes are transferred from related species as well as risk of unintended effects are also low. Some countries, regulate it as conventional breeding and other regulate it as GMO breeding.

Introduction
Definition of heterosis
The word “heterosis” was coined by G.H. Shull in 1914 as a convenient abbreviation for awkward phrases like ‘stimulation of heterozygosis’. When two genetically diverse parents are crossed, the resulting F1 or hybrid progeny has superior performance over both of its parents which is known as heterosis. The F1 or hybrid has superiority in vigour, adaptability, stress tolerance, growth rate, population fitness, biological and economic yield. Luxuriance on the other hand is a more general term often confused with heterosis, used to describe plant’s overall healthy and abundant growth, regardless of its genetic background (Allard, 1960). Charles Darwin introduced the concept of hybrid vigour in 1876, a term closely related to heterosis. The exceptional hybrid vigour in the F1 generation stems from the theory of dominance and codominance, offering numerous advantageous characteristics, particularly economically significant ones.
Heterosis is confined to F1 or hybrid generation only. The F2 and subsequent generations do not show heterosis due to factors like recombination and segregation, which lead to shuffling of the genes and produce variety of new combinations, hence they are neither homogenous like F1 nor have hybrid vigour. One of the main characteristics of heterosis is that it is highly variable from crop to crop as well as from cross to cross. So, some of the crosses will exhibit higher heterosis than the other crosses. This is because heterosis is controlled by many factors which include the genetic diversity of parents, combining ability of parental lines, genetic background, additive, dominance, epistasis nature of gene imparting heterosis which will be dealt in detail in next sections of the book.
Heterosis, manifested in positive (yield, quality, disease resistance) or negative (plant height, maturity duration) aspects, is more prevalent in crosspollinated species than in self-pollinated ones. It can be fully exploited in hybrids or partially exploited in synthetic and composite varieties. The performance of hybrids relative to parents exhibits distinct features, as illustrated in Figure 1, including better-parent heterosis with optimal trait values surpassing either parent. Mid-parent heterosis exceeds the parental average but holds limited agronomic relevance. Phenotypes are broadly categorized as additive (similar to parental average) or non-additive, further subdivided into partially dominant, dominant, and over/under dominant. Factors influencing heterosis include genetic diversity, combining ability, genetic background, and the interplay of additive, dominance, and epistatic genetic factors, explored in detail in subsequent sections.

Introduction
Angiosperms produce attractive and intricately structured flowers, within which their reproductive process occurs. In flowering plants, as in other plant groups, a diploid spore-producing generation (sporophyte) alternates with a haploid gamete-producing generation (gametophyte). The flower contains specialized structures, such as the stamen (or androecium) and the pistil (or gynoecium), where the respective male and female gametophytes are formed. The pollen grain serves as the male gametophyte, while the embryo sac serves as the female gametophyte. These gametophytes are responsible for producing sperm and egg cells, respectively facilitating their union during fertilization. The pollen grain contains the male gametophyte in angiosperms or gymnosperms. Conversely, spores function as a resting and dispersal phase for cryptogams (Moore et al., 1991). The study of pollen grains (produced by seed plants, angiosperms and gymnosperms) and spores (produced by pteridophytes, bryophytes, algae and fungi) is known as palynology. This discipline examines the structure and formation of pollen grains and spores, their dispersal and their preservation under various environmental conditions. Palynology serves as a valuable research tool for understanding many aspects of plant and animal metabolism. Moreover, a deeper understanding of pollen can aid plant breeders in enhancing efforts to improve global food and fiber supplies. In the anthers of higher plants, neither the developing pollen nor the surrounding tissues exhibit autonomous growth and development. Instead, the developing anther functions as a system where the gametophytic and sporophytic generations of the plant communicate, coordinate and co-participate in development. This chapter aims to understand the various aspects of gene activity that occur during pollen development.

Introduction
Domestication is the process of adapting wild plant species for human cultivation and consumption and it has played a pivotal role in shaping modern agriculture. Since the dawn of civilization, humans have selectively bred plants to enhance desirable traits, such as increased yield, improved taste, and resistance to pests and environmental stresses. Through domestication, early agriculturalists inadvertently altered the genetic makeup of wild progenitors, favouring traits that aligned with their needs and preferences. This process involved selecting and propagating plants with desired characteristics over successive generations gradually transforming once-unruly wild species into more docile, productive and palatable varieties. The domestication of crop plants was a gradual and ongoing process, often spanning thousands of years. It required keen observation experimentation, and an inherent understanding of plant biology and genetics even before these concepts were formally understood. This patient and persistent effort by our ancestors paved the way for the development of diverse and nutritious food sources, enabling the establishment of sedentary communities and the rise of complex civilizations. While modern breeding techniques have advanced significantly, the fundamental principles of domestication remain a cornerstone of crop improvement efforts. By understanding the historical significance and underlying mechanisms of domestication, we can better appreciate the invaluable contributions of our ancestors and continue to build upon their legacy, ensuring a sustainable and diverse food supply for generations to come.
The current state of food systems is being challenged due to the heavy reliance on a limited number of resource-intensive staple crops. The emphasis on maximizing yield and the consequent reduction in diversity over the course of domestication history has led to the development of contemporary crops and agricultural practices that are environmentally unsustainable, susceptible to the impacts of climate change, lacking in essential nutrients, and contributing to social inequalities. For many years, researchers have advocated for diversification as a viable solution to tackle the issues surrounding global food security. In this context, we present a vision for a new phase of crop domestication, which aims to expand the range of crop diversity. This approach involves active engagement and benefits for three key components of domestication: a) the cultivated crops themselves, b) the surrounding ecosystems, and c) the human populations depending on these crops. We delve into the potential of current tools and technologies to initiate a revival of diversity within existing crops, enhance the value of underutilized crop varieties, and introduce new crops into cultivation. This multipronged strategy aims to reinforce genetic diversity, promote resilient agroecosystems, and establish a more varied and robust food system. The successful execution of this renewed phase of domestication hinges on a bold commitment from researchers, funders, and policymakers to invest in both fundamental and practical research efforts. As we navigate the challenges of the anthropocene epoch, characterized by significant human impact on the environment, the process of domestication offers a pathway to construct more diverse and adaptable food systems that can better serve humanity’s needs.

Introduction
With advancements in molecular biology, DNA-based technologies have shown great potential in enhancing the efficiency of crop breeding programs, preserving germplasm resources, improving the quality and yield of agricultural products, and protecting the environment. As a result, their role in modern agriculture is becoming increasingly important.
DNA is the main genetic materials of all cellular organisms; preserving DNA itself is one way of preserving germplasm resources (Geptset al.,2006). The advancement of biotechnology and molecular biology has made it possible to regulate or even control plant traits using DNA sequence information, including its structure, function, and mechanisms.DNA technologies based on DNA molecular markers, transgenic technology and gene expression have been widely used in agricultural production which have showed great potential in improving agricultural yields and quality, reducing the loss that various biotic and abiotic stress caused, promoting the utilization of germplasm resource, improving breeding efficiency and strengthening the regulation of plant growth. (Garciaet al.,2005)
These modern DNA technologies, with their high feasibility and necessity, play a crucial role in ensuring the sustainable development of agriculture. Although agriculture encompasses both plant and animal production, DNA technologies in these fields share similar technical purposes and types. Therefore, this study focuses on reviewing the agricultural applications of DNA technologies by exploring their utilization in plant production. Numerous reports have documented the application of various DNA technologies in agricultural production. However, as these technologies continue to evolve and advance, it becomes challenging to cover every DNA technique in detail..DNA technology holds immense promise for the future of crop identification, enabling precise and efficient breeding, accelerating the development of improved varieties, and contributing to sustainable food systems. Here’s a breakdown of the key future prospects:

Introduction
Identification of crop varieties is one of the major tasks required in modern agriculture, plant breeding, and seed certification systems. The correctness of identification ensures that the varietal purity is sustained, advocates the rights of plant breeders, and guarantees quality seeds that will perform expectedly under specified agro-climatic conditions to farmers (Yu and Chung, 2021). The growing number of crop varieties due to the intensive breeding programmes all over the world makes it equally important to be able to differentiate between cultivars. Variety identification serves several purposes, such as:
• Seed Quality Assurance: Used to prevent the sale of spurious or mislabeled seeds.
• Intellectual Property Rights (IPR): Legal protection of new plant varieties by acts like the Plant Variety Protection (PVP).
• Biodiversity Conservation: Tracking and documenting existing genetic resources.
• Regulatory Compliance: Aids in Distinctness, Uniformity and Stability (DUS) testing protocols.
• Traceability in Food Supply Chains: Ensures safety for consumers and compliance with labeling standards.
Thus, crop variety identification forms the basis of integrity in agricultural systems and is the coordination mechanism for protecting innovations in plant breeding with regulatory frameworks both at national and international levels (Jones et al., 2013; Kage et al., 2016; Cockram et al., 2012).

Introduction
The accurate identification of crop varieties is crucial for agriculture, plant breeding, and intellectual property protection. DNA-based techniques have emerged as powerful tools for distinguishing between crop varieties due to their precision and reliability. However, several challenges persist in the adoption and implementation of these techniques. Conventionally, morphological descriptors are routinely used for establishing the identity of varieties. But these morphological descriptors suffer from many drawbacks such as influence of environment on trait expression, epistatic interactions, pleiotrophic effects etc. Furthermore, the paucity of sufficient number of these descriptors for unequivocal identification of increasing number of reference collection of varieties enforces to look for alternatives. Electrophoresis of seed proteins and isozyme analysis have overcome these limitations to some extent but now many powerful DNA based techniques are available. Since all genetic differences between individuals are laid down in the primary sequence of their genomic DNA, the straightforward method of identification of crop varieties and parental lines would be to determine this sequence for the genome under comparison. Sequencing requires huge monitory investment and it is practically impossible to sequence the whole genomes of all varieties. But with the automation in sequencing now possible, short stretches of amplified DNA can be sequenced. However, a more practical strategy would be to limit the comparisons to specific regions of the genome, which frequently differ between individuals.

Introduction to Molecular Markers in Vegetable Breeding
As global demand for food continues to rise, the agricultural sector faces mounting challenges from climate change and resource limitations. These pressures necessitate an urgent transformation in farming practices, making molecular markers vital for enhancing crop improvement strategies (Tester and Langridge, 2010). Traditional breeding techniques, which often rely on phenotypic selection and protracted breeding cycles, find it increasingly difficult to produce resilient, high-yield cultivars (Bernardo, 2016). Molecular markers, including Single Nucleotide Polymorphisms (SNPs), Simple Sequence Repeats (SSRs), and Amplified Fragment Length Polymorphisms (AFLPs), provide direct access to plant genomes, allowing for the precise identification and manipulation of desirable traits regardless of environmental variability (Varshney et al., 2005). This approach is essential for expediting breeding programs and enhancing genetic gains, ultimately leading to crops better suited for diverse and evolving climates (Jannink et al., 2010).Additionally, the integration of genome-wide association studies (GWAS) and genomic selection (GS) harnesses high-density marker data to deepen our understanding of complex trait genetics, fostering sustainable agricultural practices and securing future food supplies (Hickey et al., 2019).

Introduction
In the realm of modern agriculture and plant breeding, the integration of advanced biotechnological tools has revolutionized the traditional methods of crop improvement. Traditional approaches to genetically improving horticultural crops that are primarily propagated asexually encounter multiple challenges. These include an extended juvenile phase, the absence of seeds, a high level of intraand interspecific incompatibility, frequent heterozygosity, seed sterility, and, most importantly, the restriction of certain valuable traits to wild species (Mehlenbacher, 1995). Conventional or classical breeding techniques rely on natural processes and traditional tools to develop new plant varieties or cultivars. However, these methods are often time-consuming, labor-intensive, and less efficient. The lengthy process, coupled with the challenges of maintaining desirable traits, makes it difficult to achieve rapid genetic improvements. As a result, there is a growing need for more advanced and precise breeding methods to enhance crop development (Jain and Kharkwal, 2004). A molecular marker is a specific DNA segment that signifies genetic variations at the genome level, aiding in genetic analysis and breeding (Dhutmal et al., 2018). These are composed of nucleic acids as well as proteins and used on basis of naturally occurring polymorphism (Thottappilly et al., 2000; Ahmad et al., 2020). These markers are closely related with the target gene and they act as sign or flags (Nadeem et al., 2018), aiding in the identification of specific regions associated with advantageous characteristics such as disease resistance, yield potential, nutritional content, and environmental adaptability (Meena et al., 2023).The advancement of high-throughput molecular markers and genetic maps has enabled the precise identification of genes responsible for agronomically important traits, potentially enhancing breeding through markerassisted selection (MAS). Compared to traditional breeding methods, MAS overcomes the challenges of phenotypic selection and significantly improves selection efficiency. This approach accelerates crop improvement by ensuring the effective transfer of desirable traits with greater accuracy and reliability (Wani et al., 2022). The incorporation of next-generation sequencing (NGS) technologies and high-throughput genotyping platforms has also facilitated genome-wide association studies (GWAS) and the discovery of single nucleotide polymorphisms (SNPs) linked to important traits, further enhancing the resolution of genetic analysis. In recent years, molecular markers have been extensively used to characterize and enhance genotypic and phenotypic traits in temperate fruit and nut crops. Studies have focused on assessing genetic diversity in almonds, identifying genes responsible for red skin color in apples, developing sharka disease-resistant apricots, and sequencing the almond genome. These markers have been successfully used for genetic studies in many horticultural crops including vegetables (Gulsen et al., 2007; Kumar et al., 2008 a and b; Schafleitner et al., 2013; Yadav et al., 2015; Sharma et al., 2016; Kumar et al., 2017 and Kumar et al., 2019) and flowering crops (Kumar et al., 2019; Kumar et al., 2016 and Kumar et al., 2018a and b). These advancements highlight the crucial role of molecular markers in improving breeding strategies, accelerating genetic improvements

Introduction
DNA fingerprinting envisages a very significant molecular methodology employed for identification and characterization of wheat varieties and germplasm. It is of utmost importance in varietal authentication, rights protection of breeders, and analysis of genetic diversity. Currently employed molecular markers like SSRs, SNPs, and DArT are applied extensively for wheat fingerprinting. Such markers precisely differentiate closely related varieties and aid in breeding programs (Babu et al., 2020; Kiss et al., 2021).
The current standing of wheat DNA fingerprinting shows a trend toward high-throughput genotyping and genomic selection strategies to accelerate crop improvement. Future prospects would entail the integration of advanced sequencing technologies such as Next-Generation Sequencing (NGS) and machine learning for genetic analysis. These technologies will ease wheat breeding and dramatically contribute to food security and climate-resilient agriculture. Expanding the global DNA fingerprinting database would further enhance global wheat germplasm conservation and utilization (Sandhu et al., 2021; Ahmadi et al., 2020). Wheat (Triticum spp.) is one of the major staple crops of the world, supporting the sustenance of over one-third of the total world population. It is the main source of carbohydrates, proteins, fibers, and other important micronutrients, making it very important for human nutrition. Wheat is cultivated mainly in all types of agro-climatic zones, with major producers being China, India, Russia, United States, and the European Union.
Wheat is highly valuable not only in terms of food security, but also economically with millions of farmers involved in its production and trading worldwide. Wheat is an important raw material for many food products, such as bread, pasta, and baked goods. Wheat production faces challenges from climate change, pests, and emerging pathogens. Therefore, continuous research on wheat, genetic improvement for desirable traits, and sustainable agricultural practices are needed to enhance yield, resilience, and in turn global food security. Genetic diversity in wheat is pertinent for fulfilling food security at the global level and for the success of breeding programs, apart from giving diverse traits for resistance against pests, diseases, and environmental stresses like droughts