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As the effects of climate change become increasingly apparent and inescapable, human society is at a tipping point at present. The effects of climate change are unparalleled worldwide, ranging from rising temperatures that threaten food production to melting glaciers that result in catastrophic flooding and erosion. Geneticists and plant breeders remain under pressure to sustain food production through revolutionary breeding techniques and the improvement of minor crops that are resistant to both biotic and abiotic challenges and are well-suited to the marginal soil and source of nutrition. The modern and innovative technologies used by breeder may save mankind from impending agricultural problems brought on by changing weather patterns, pests that are emerging quickly, and finite resources. Every crop development initiative must, invariably, unlock the reservoir of genetic diversity and make full use of wild germplasm. But present advances in high-throughput phenomics, breeding strategies, genomics, and genome editing, bring up new avenues for accelerating the improvement of crops suitable in climate change scenario. In order to achieve sustainable agricultural production and improved food security, this book discusses the development of innovative modern methodologies to supplement conventional plant breeding for the production of new crop varieties under the increasingly restrictive environmental and cultivation component. The chapters provide in-depth information as well as current research on certain selected topics that will help understand the recent developments in plant breeding. Plant breeders and geneticists engaged in breeding assignments integrating traditional breeding with biotechnology and molecular breeding methods and also advanced undergraduate and graduate students will find the book to be a valuable resource.

This chapter covers plant breeding’s present, past, and future prospects with a special emphasis on cultivar development. In order to increase agricultural production and productivity (yield per unit area) of important crops, plant breeders have achieved significant achievements in the genetic enhancement of yield, adaptive features, disease–pest resistance, abiotic stress tolerance, and nutritional qualities. Plant breeding is more crucial than ever to address production issues in order to provide a steady supply of food, feed, and fiber due to the growing demands of the human population and rising climate fluctuations. Now a days plant breeders have advanced tools to create superior cultivars because of recent technological developments in the fields of phenomics, genomics, and biotechnology. This chapter has covered important topics of crop domestication, pre-Mendelian and post Mendelian plant breeding, plant breeding in the 20th and 21st centuries, including information on the green revolution, genetically engineered crops, molecular marker applications, image-based phenotyping, machine learning techniques, and the relationship between both public and private plant breeding organizations, and future plant breeding efforts.

Modern and transgenic breeding approaches consist of modern plant breeding triangle, high-throughput phenotyping (HTP), marker-assisted selection (MAS), marker-assisted backcrossing (MABC), genomic selection (GS), genome-wide association study (GWAS), and genome editing. MAS accelerates trait identification through DNA markers, improving efficiency in selecting plants with desired traits. MABC employs molecular markers to facilitate gene introgression from donor parents (DPs) to superior recurrent parents (RPs). GS employs genome-wide markers to predict performance, revolutionizing breeding by considering both major and minor-effect quantitative trait loci (QTLs). Genome editing techniques like CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats associated protein 9) enable targeted gene modifications for desired traits. Genome editing involves selecting target genes, designing guide RNAs for Cas9, and introducing the CRISPR-Cas9 system into plants. This technology has been utilized to enhance crop productivity, sustainability, and disease resistance. Transgenic crops are designed to carry specific traits, such as pest resistance, virus resistance, abiotic stress tolerance, and nutritional enrichment. Agrobacterium tumefaciens is highlighted as a tool for transgene introduction, offering advantages like low copy number integration and stable expression. Genetic engineering remains a promising avenue for creating disease-resistant crops and ensuring global food security.

The chapter “Breeding Strategies for Disease Resistance” provides a comprehensive exploration of addressing disease resistance through various breeding strategies. In an era of escalating global challenges and climate change, where crop failures can lead to food shortages and economic instability, the chapter delves into strategies that integrate traditional breeding methods with cutting-edge genetic advancements to strengthen plants against pathogens. Understanding the genetics of plant–pathogen interactions holds profound importance. This knowledge elucidates the mechanisms underpinning disease development and offers insights into developing targeted strategies for disease management. By deciphering the genetic details governing host susceptibility and pathogen virulence, we gain the ability to engineer crops with enhanced resistance, reducing reliance on chemical interventions and promoting sustainable agriculture. The chapter further discusses the mechanism of disease resistance in plants which involves inherent genetic traits that identify pathogen molecules, triggering a rapid defense response called “gene-for-gene” interaction. Systemic acquired resistance (SAR), where a local pathogen attack prompts the entire plant to boost its defense preparedness. Signaling molecules like salicylic acid play a pivotal role. Additionally, plants employ chemical defenses via secondary metabolites and leverage beneficial microorganisms to stimulate immune pathways. This coordinated approach empowers plants to effectively counter pathogens and elevate disease resistance. In this chapter, we discuss breeding strategies for disease resistance that encompass a range of vital approaches. Traditional methods involve selecting and breeding plants with inherent resistance traits and incorporating genes from related species to enhance defenses.

Our natural ecology comprises insects, which are known to have both advantageous and detrimental consequences. Insect pests are the main obstacles in maximizing agricultural crop output, since they directly or indirectly result in significant crop loss. The intricate relationship that phytophagous insects have with their hosts is the result of a protracted and ongoing evolutionary process. Because of this, it is impossible to completely eradicate them, but there is a hopeful fix for this issue, i.e., utilizing insect resistant crop varieties. Insect-resistant kinds are those that, with the same starting infestation level and similar environmental conditions, yield considerably higher yields of high-quality fruit than susceptible varieties. By boosting yield and reducing pesticide use, these varieties had an enormous economic benefit. There are a number of highly effective insect resistance mechanisms that the targeted insect pest cannot simply overcome. This chapter discusses various breeding strategies such as introduction, selection, and hybridization as well as some modern breeding approaches that have been used to develop many insect-resistant crop varieties that have significantly improved the world’s food supply, by reducing carbon inputs through reduced pesticide use. By expressing bacterial endotoxins and producing Bacillus thuringiensis (Bt) crops, genetic engineering also aids in the production of insect-resistant crops. Furthermore, RNA interference (RNAi) and genome editing by CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR associated 9) offer new avenues for the production of insect-resistant crops.

Salinity stress poses a significant threat to agricultural productivity worldwide, impeding crop growth and yield potential. Developing crop varieties with enhanced salinity tolerance is essential for ensuring food security and sustainable agriculture. Salinity stress, resulting from excessive salt accumulation in soil and irrigation water, adversely impacts crop growth, water uptake, and nutrient assimilation. Traditional breeding methods, coupled with recent advancements in molecular and genomic techniques, have enabled the development of crop varieties capable of thriving in saline environments. Genetic diversity serves as the foundation for breeding efforts, allowing the identification and selection of individuals with inherent salinity tolerance traits. Utilization of wild crop relatives and landraces provides a valuable reservoir of genetic variation for salinity stress adaptation. Incorporation of molecular markers into breeding programs expedites the selection of desirable traits. Quantitative trait loci (QTLs) associated with salinity tolerance are identified through techniques such as genome-wide association studies (GWAS) and linkage mapping, facilitating marker assisted selection. Additionally, recent strides in gene editing technologies like CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats–associated protein 9) offer precise modification of candidate genes responsible for salinity response, accelerating the breeding process. A holistic approach encompassing physiological and biochemical aspects is crucial for accurate phenotypic selection. Traits, such as ion homeostasis, osmotic adjustment, and antioxidative capacity, provide insights into a plant’s salinity tolerance potential

Introduction One of the biggest problems emerging for the survival of the people in the future is food security. To feed an anticipated nine billion people by 2050, the globe would need to produce roughly twice as much food as it does today. In order to properly accomplish this aim, food production must be elevated sustainably on currently available arable land while addressing the problems brought on by climate change. Over the past five decades, crop yields have steadily increased due to crop breeding programs and better management practices. The rate of yield improvement has, however, reached a plateau (Grassini et al. 2013). The noncompounding yearly yield growth of 0.9% for wheat at the present time, world output rises by 38%, is quite small, and is unable to fulfill expected demand levels by 2050. Therefore, the most beneficial course of action is to investigate more effective, higher-yielding crops (Ray et al. 2013). Historically, the genetic improvement of wheat has been accomplished by sexual hybridization between related species, giving rise to a large number of cultivars with excellent agronomic performance and high yields. The main methodology for improving cereal crops is still traditional plant breeding, sometimes in combination with traditional cytogenetic methods (Salina et al. 2015). Cereal crops immediately became the top targets for genetic modification due to the worldwide importance of cereal grains in human diets. Over the past 10 years, wheat genetic technology for processing has advanced quickly.

Transgenic crops, developed through genetic engineering techniques, have revolutionized modern agriculture by conferring novel traits that enhance yield, quality, and resilience. This chapter delves into the intricate interplay between the scientific advancements in breeding approaches for transgenic crops and the critical ethical concerns and regulatory frameworks that accompany them. The chapter begins by introducing the concept of transgenic crops and provides an overview of the diverse breeding techniques employed to manipulate plant genomes. These techniques include Agrobacterium mediated transformation, biolistic transformation, CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats–associated protein 9) genome editing, RNA interference (RNAi), and site-specific integration methods. Each method is presented within the context of its potential benefits and limitations. The subsequent sections address the ethical considerations that arise from the creation and deployment of transgenic crops. The potential ecological and biodiversity impacts, cross-contamination risks with conventional crops, and issues related to patenting genetically modified organisms (GMOs) are explored. Furthermore, the chapter examines the ethical implications of genetically modified crops on human and animal health and questions surrounding the monopolization of seed resources. Looking to the future, the chapter outlines emerging breeding technologies and anticipates potential challenges in ethical consideration and regulation.

Introduction The main goal of plant breeding is to increase crop yield and the second goal is to improve quality, develop light- and heat-insensitive varieties, tolerance to biotic and abiotic stresses, simultaneous maturation, and water and nutrient use. Efficiency, elimination of toxins, and cultivation of different product groups allow to achieve high agricultural yields and sustainable development. Better understanding and development of genetics has increased the efficiency of plant breeding to achieve desired goals in agricultural crops. Effective and efficient use of molecular markers in crop improvement programs increases selection efficiency and productivity and accelerates the growth cycle to create new varieties with good results. Marker assisted selection (MAS) is a technique that uses markers (morphological, biochemical, or DNA/RNA variation-based markers) to indirectly select for traits of interest (e.g., productivity, disease, genetic determinants resistance, abiotic stress tolerance and/or quality). This process is used in plant and animal breeding. The rapid development of biotechnology has allowed breeders to develop better selections to replace traditional selections based on phenotypic pedigree.

Genome editing has revolutionized plant breeding, offering precise and efficient methods to enhance crop traits. This chapter provides an overview of genome editing’s principles, applications, challenges, and future prospects in plant breeding. The chapter explores genome editing technologies, with a focus on CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats-associated protein 9), TALENs (transcription activator-like effector nucleases), and ZFNs (zinc finger nucleases). CRISPR-Cas9, in particular, has become the go-to tool for precision breeding, allowing scientists to target and modify specific genes with unprecedented accuracy. Applications of genome editing in plant breeding are diverse. It enables the development of crops with enhanced disease resistance, drought tolerance, and improved nutritional content. Additionally, genome-edited crops reduce environmental impact by requiring fewer chemical inputs and promoting sustainable farming practices. Accelerated breeding shortens the time needed to create new crop varieties, addressing urgent agricultural challenges. Looking ahead, the future of genome editing holds exciting possibilities. Continuous advancements in technology promise even more precise editing tools and high-throughput capabilities. Precision breeding will become the norm, allowing for tailored crop varieties and customized agricultural practices.

The whole genome sequencing helps the researcher to identify the desired gene and make it useful for the breeding program by transferring that particular gene into improved cultivar. Since, the whole genome sequence is not available for all crops and animals; there is a need of advanced techniques to overcome this problem. One such technique is TILLING (Targeting Induced Local Lesions IN Genomes) and its related technique called Eco-TILLING. TILLING is a reverse genetic approach used to identify the point mutation created by chemical mutagen in the mutagenized population. The chemical mutagen is most widely used and it will create allelic series of mutations which include nonsense, missense, or splice site mutation. The individuals with mutation were pooled by two-dimensional or three-dimensional pooling techniques. These mutations were identified by the formation of heteroduplex complex in the mutated region of the gene. Then, the heteroduplex is cleaved by S1 nuclease family enzyme and were examined in gel electrophoresis which distinguishes heteroduplex from homoduplexes. Now, the identified mutants in gel electrophoresis were subjected to sequencing for confirmation. Eco TILLING is similar to the TILLING except for the mutant population, as we use the natural mutant population in Eco-TILLING; whereas in TILLING we use the artificial mutant population and also pooling is done with reference sample in Eco-TILLING. The advantage of TILLING is that it is a cost-effective, rapid screening of mutant population and a nontransgenic approach as it does not require biosafety measures.

Two cornerstone methodologies in genetics, forward genetics and reverse genetics, illuminate the intricate connection between gene sequences and their functions. Forward genetics traditionally entailed laborious steps, beginning with the observation of mutants and culminating in the identification of causal genetic alterations. While effective, this approach was time-consuming and limited in scalability. Recent innovations have revolutionized forward genetics with next-generation sequencing (NGS), genome-wide association studies (GWAS), CRISPR (clustered regularly interspaced short palindromic repeats)-based screens, and advanced computational techniques. These advancements deliver precision and efficiency, enabling researchers to explore gene function on an unprecedented scale. In contrast, reverse genetics initiates its journey armed with sequence data and harnesses the manipulation of genes to observe resultant phenotypic shifts. Traditional reverse genetics, though invaluable, faced challenges like limited precision and scalability. Cutting-edge approaches have transformed the landscape. Techniques such as prime editing, base editing, high-throughput functional genomics, single-cell genomics, and synthetic biology offer unparalleled precision and capacity. They empower scientists to scrutinize gene function at the single-cell level, conducting precise genome editing and large-scale functional genomics studies. These strides in forward and reverse genetics have charted new territories for genetic research.

Introduction Crop improvement lies at the heart of ensuring food security, agricultural sustainability, and the resilience of our farming systems. As we confront a world characterized by climate variability, emerging pests, and a growing global population, the need for innovative approaches to crop enhancement becomes paramount. This is where the concept of pre-breeding steps in: a fundamental phase that acts as a bridge between the untamed genetic diversity of wild plants and the refined traits of cultivated crops. Pre-breeding represents the exploration, identification, and incorporation of valuable genetic traits from the vast array of plant species that often remain on the fringes of agricultural attention. These “wild relatives” and underutilized varieties possess traits that have evolved over time to withstand diverse environmental stresses, combat diseases, and adapt to changing conditions. Pre-breeding aims to tap into these reservoirs of genetic potential, merging them with the qualities we value in our cultivated crops. At its core, pre-breeding is a scientific journey of discovery and innovation. It involves the strategic selection and hybridization of plant materials, guided by a vision of enhancing crop performance across multiple fronts. The goal is to create crop varieties that are not only productive and high yielding, but also equipped to thrive in the face of evolving challenges. This involves a delicate dance between tradition and cutting-edge techniques as well as collaboration between breeders, geneticists, and researchers (Qureshi et al. 2014).

Wide hybridization or distant hybridization is crossing between two different species or genera, and has been used successfully to transfer genes and to create new crop species. Wild plant species related to crop plants form an important source of useful traits for quality improvement and biotic and abiotic stress tolerance. Cultivated species has lost many beneficial traits for stress tolerance in the process of domestication and selection, which resulted in uniformity in many agronomic traits. Although there have been multiple cases of valuable tolerant genes being transferred from wild rice to cultivated rice, it is now necessary to look at new breeding and selection strategies that may be applied to wide hybridization. It breaks the species barrier for gene transfer and makes it possible to transfer the genome of one species to another, which results in changes in genotype and phenotype of the progenies. The barriers in wide hybridization occurs as prezygotic and postzygotic barriers. Techniques of chromosome doubling, bridging species, protoplast fusion, and embryo rescue are highly beneficial in recovering fertile progenies by overcoming various barriers in wide crossings. Broadening the gene pool of a crop is an important plant breeding method as it can enhance tolerance of major biotic and abiotic stresses and improve the quality characteristics of the plant.

Conventional crop breeding requires a substantial investment of time, space, and resources for the selection process and the subsequent crossing of desired plants. The time taken for the complete seed-to-seed cycle is a critical constraint in the advancement of plant research and breeding. The concept of speed breeding holds the promise of diminishing the duration necessary for the entire process of cultivar development, from creation to introduction and eventual commercial availability, thereby enhancing the improvement of both food and industrial crops. It revolves around optimizing conditions such as light intensity, temperature, and daylight duration (22-hour light, 22°C day/17°C night, and high light intensity). This approach enhances photosynthesis, triggering early flowering, and, in combination with yearly seed collection. The adoption of speed breeding shows promises in realizing nutritional security and promoting sustainable agriculture for the future rising population. The technique’s integration with advanced genomics and gene editing opens doors to precise trait incorporation. Moreover, speed breeding reduces resource consumption, aligning with sustainability goals. As local adaptations become feasible, it empowers diverse regions.

Epigenetics is a new field of research in plant biology, which aims to provide a powerful tool to improve crop productivity, adaptability, and resistance to biotic and abiotic stresses. In recent years, researchers have begun to explore the potential of epigenomics in plant breeding, providing breeders with an alternative to genetic engineering, addressing concerns related to genetically modified organisms (GMOs) in agriculture. In particular, epigenetic markers (epimarkers) are chemicals which regulate genes by sitting over the DNA sequence; they explore the consequences of thermal and ionic variation on the behavior of plant under stress conditions. Moreover, epialleles may be promising sources of new variation of traits that are controlled by genes that are not detrimentally regulated. In this chapter, we provide an overview of the current state of the art in epigenomic research, focusing on the impact of next-generation sequencing (NGS) on epigenomes, as well as the potential use of epigenetics in crop breeding. Introduction Epigenetics is the study of heritable changes in gene expression that occur without alterations in the DNA sequence. It involves modifications of the DNA or associated proteins that can influence gene activity and expression. Most cells in an organism share the same genes, although they can be very diverse from one another. This is due to the fact that not all genes are active in all cells at the same time. The epigenetic context of a gene, or its accessibility to transcription, can tell whether the gene is likely to be active or not (Klemm et al. 2019). Indeed, the nuclear genome is found as a dense combination of long DNA strings wrapped around specialized proteins called histones to create nucleosomes (Samo et al. 2021). These nucleosomes can be further packed together to form even denser 3D formations that are sometimes visible under a microscope, giving rise to the term “chromatin”.

Introduction Breeders expect a new variety to show high performance for yield and its contributing characters along with other physiological and nutritional traits. A variety is said to be superior not only for its higher economic yield, but also for its consistent performance over a wide range of environmental conditions. But the performance of a particular variety is the resultant of its genetic constitution and the environment in which it has been grown. Particular variety may not exhibit same phenotypic performance under different environments, or different varieties may perform differently to a specific environment. The basic cause of differences in the stability of different genotypes is the interaction effect of genotype and environment, known as genotype × environment (G × E) interaction (GEI). The term environment refers to the uncontrolled external conditions that affect expression of genes of an individual genotype such as the annual rainfall, dry spells, soil fertility gradients, waterlogging, depth and texture of soil, and photoperiod and incidence of disease or pests. However, prediction of GEI is seldom possible with available and known factors. Therefore, the environmental factors can be categorized as predictable and unpredictable environmental factors (Table 1).

Introduction Intellectual property encompasses the products of human creativity, including inventions, artistic works, and commercial symbols. It can be categorized into two main types: industrial property and copyright. Industrial property covers patents, trademarks, industrial designs, and geographic indications of source. Copyright, on the other hand, protects literary and artistic works such as novels, poems, films, music, and visual arts. Intellectual property rights (IPRs) also extend to related areas such as performers’ rights, recording producers’ rights, and broadcasting rights. These rights safeguard the interests of creators by granting them exclusive ownership over their creations. However, unlike tangible property, intellectual property lacks physical characteristics and must be expressed in a discernible manner to be protected. Traditionally, intellectual property comprised four primary types: patents, trademarks, copyrights, and trade secrets. However, the concept has evolved to encompass newer forms, such as geographical indications, plant variety protection, semiconductor and integrated circuit (IC) protection, and undisclosed information. This expansion reflects the changing landscape of innovation driven by rapid technological, scientific, and medical advancements.

A Abbreviated 177 Abiotic stresses 11, 60, 79, 101, 163, 164, 195, 196, 198, 210 Abscisic acid 65, 198 Accessibility 142, 196, 199 Agrobacterium-mediated transformation 23, 85, 86, 89, 97, 116 Allotetraploid 165 Alterations 80, 93, 139, 140, 141, 178, 195, 196, 204 Amplified fragment length polymorphism 102 Analyzer 107, 129, 132 Annealing 129, 132 Antibiosis 49, 50, 51 Antibodies 76 Assimilation 59, 178 Avirulence 32, 33, 34, 35 Avoidance 30, 49, 51, 60