1 Introduction

Maize (Zea mays L.) is one of the most significant staple crops globally, alongside rice and wheat, contributing to 60% of the world’s caloric intake. Its importance is underscored by its extensive cultivation and utilization across various regions, including sub-Saharan Africa, Southeast Asia, and Latin America, where it serves as a primary food source. The crop’s versatility extends beyond human consumption, as it is also a critical feed crop for livestock and a burgeoning resource for biofuel production. The nutritional profile of maize, rich in macronutrients and micronutrients, makes it integral to global food security and nutrition (Palacios-Rojas et al., 2020).

The continuous improvement of maize through breeding is vital for addressing the growing demands for food, feed, and bioenergy. With the global population projected to reach 9.7 billion by 2050, enhancing maize productivity and nutritional quality is crucial for food security (Muntean et al., 2022). Traditional and modern breeding techniques, including biofortification and genetic engineering, have been employed to develop maize varieties with improved traits such as higher yield, enhanced nutritional content, and resistance to environmental stresses. These advancements not only contribute to human health but also open new market opportunities for maize producers (Palacios-Rojas et al., 2020). Moreover, the integration of genomic tools and biotechnological approaches has accelerated the development of high-performance maize hybrids, essential for coping with climate change and ensuring sustainable agricultural practices (Andorf et al., 2019; Muntean et al., 2022).

This study aims to gain a comprehensive understanding of how genetic engineering can enhance corn breeding to meet the needs of population growth and changing environmental conditions, including assessing the impact of GM on corn yield, nutritional quality, and stress resistance, as well as considering the socioeconomic and regulatory implications of these advances.

2 Traditional Maize Breeding Approaches

2.1 History of maize domestication and early breeding efforts

Maize (Zea mays L.) has undergone a remarkable transformation from its wild ancestors to the staple crop it is today. The domestication of maize began around 9 000 years ago in the Balsas River Valley of Mexico. Early farmers selected for desirable traits such as larger kernels and cobs, which led to the gradual evolution of maize from its wild progenitor, teosinte, to the modern varieties we see today (Figure 1) (Chen et al., 2020). This process of domestication was driven by human selection for traits that improved yield, ease of harvest, and adaptability to different environments. The early breeding efforts were largely empirical, relying on the visual selection of superior plants and seeds, which provided scientific evidence for more systematic breeding approaches in later centuries.

Figure 1 Crucial morphological changes during maize and rice domestication and the underlying key genes (Adopted from Chen et al., 2020) Image caption: Top, wild rice to cultivated rice; bottom, teosinte to maize (Adopted from Chen et al., 2020)

2.2 Limitations of conventional breeding methods

Conventional breeding methods, including hybridization and selective breeding, have been instrumental in improving maize yields and adaptability. However, these methods have several limitations. One major limitation is the time required to develop new varieties, as multiple generations of crossing and selection are needed to achieve desired traits. Additionally, conventional breeding relies heavily on phenotypic selection, which can be influenced by environmental factors, making it challenging to accurately select for genetic traits (Zhou and Xu, 2024). Hybridization, while effective in exploiting hybrid vigor, often requires extensive resources and labor to produce hybrid seeds. Furthermore, conventional methods are limited in their ability to introduce new traits from distant or wild relatives due to reproductive barriers and linkage drag, where undesirable traits are co-inherited with desirable ones (Muntean et al., 2022).

2.3 Successes and challenges in traditional maize improvement

Traditional maize breeding has achieved significant successes, particularly in the development of high-yielding hybrid varieties. The introduction of hybrid maize in the early 20th century led to dramatic increases in yield and productivity, contributing to food security and agricultural sustainability. The Green Revolution further exemplified the success of traditional breeding, with the development of semi-dwarf, high-yielding varieties that transformed agriculture in many parts of the world. However, these successes have not been without challenges. One of the ongoing challenges is the need to continuously develop new varieties that can withstand biotic and abiotic stresses, such as pests, diseases, and climate change (Nepolean et al., 2018; Muntean et al., 2022). Additionally, the genetic base of modern maize varieties has become narrower due to intensive selection, which can reduce genetic diversity and increase vulnerability to new threats. Addressing these challenges requires integrating traditional breeding with modern biotechnological tools to enhance the efficiency and effectiveness of maize improvement programs (Andorf et al., 2019; Lorenzo et al., 2022; Sethi et al., 2023).

3 Introduction to Genetic Engineering in Agriculture

3.1 Definition and principles of genetic engineering

Genetic engineering refers to the direct manipulation of an organism’s DNA using biotechnology. This process involves the modification of genetic material to achieve desired traits, such as increased yield, pest resistance, or improved nutritional content. The principles of genetic engineering include the identification of target genes, the use of molecular tools to modify these genes, and the integration of the modified genes into the host organism’s genome (Wu and Li, 2024). Techniques such as CRISPR/Cas9 have revolutionized genetic engineering by allowing precise edits to be made to the DNA sequence, thereby enhancing the efficiency and accuracy of genetic modifications (Lorenzo et al., 2022; Ye et al., 2022).

3.2 Key breakthroughs in genetic engineering relevant to crop breeding

Several key breakthroughs have significantly advanced the field of genetic engineering in crop breeding. The development of CRISPR/Cas9 technology has been a game-changer, enabling precise genome editing to improve complex traits such as yield and drought tolerance in crops like maize (Lorenzo et al., 2022). Another notable achievement is the creation of transgenic crops that are resistant to pests and diseases, which has been successfully applied to important crops like rice, wheat, and maize. Additionally, the biofortification of crops, such as the development of Golden Rice enriched with vitamin A, represents a significant advancement in addressing global malnutrition. These breakthroughs demonstrate the potential of genetic engineering to complement traditional breeding methods and accelerate the development of superior crop varieties (Lambing and Heckmann, 2018; Andorf et al., 2019).

3.3 Comparison between traditional breeding and genetic engineering approaches

Traditional breeding and genetic engineering are both essential methods for crop improvement, but they differ in several key aspects. Traditional breeding relies on the natural genetic variation that arises during meiosis and involves the selection and crossing of plants with desirable traits over multiple generations. This process can be time-consuming and less precise, as it often involves the transfer of large segments of DNA, including both beneficial and non-beneficial genes (Lambing and Heckmann, 2018; Li, 2020).

In contrast, genetic engineering allows for the direct modification of specific genes, providing a higher level of precision and control over the traits being introduced. Genetic engineering can introduce new traits that are difficult or impossible to achieve through traditional breeding, such as resistance to specific pests or enhanced nutritional content. However, uncertainties associated with the insertion and expression of transgenes can pose challenges, and the acceptance of genetically engineered crops varies among different regions and stakeholders.

4 Key Genetic Engineering Techniques in Maize Breeding

4.1 CRISPR-Cas9 and other gene-editing technologies

CRISPR-Cas9 has revolutionized the field of genetic engineering, providing a precise and efficient method for genome editing in maize. This technology utilizes the Cas9 endonuclease guided by RNA to introduce targeted double-strand breaks in the DNA, which can then be repaired to create specific genetic modifications. The CRISPR-Cas9 system has been successfully used for targeted mutagenesis, gene editing, and site-specific gene insertion in maize, enhancing traits such as disease resistance, yield, and stress tolerance (Svitashev et al., 2015; Chen et al., 2019; Rajput et al., 2021; Lorenzo et al., 2022). Additionally, other gene-editing technologies like TALENs and ZFNs have been employed, although CRISPR-Cas9 remains the most prominent due to its simplicity and versatility (Arora and Narula, 2017; Eş et al., 2019).

4.2 Transgenic technologies: incorporation of foreign genes into maize genomes

Transgenic technologies involve the introduction of foreign genes into the maize genome to confer new traits. This method has been instrumental in developing maize varieties with improved characteristics such as pest resistance, herbicide tolerance, and enhanced nutritional content. The process typically involves the use of Agrobacterium-mediated transformation or biolistic (gene gun) methods to insert the desired genes into the maize DNA. These transgenic approaches have significantly contributed to the advancement of maize breeding by enabling the incorporation of beneficial traits from other species (Svitashev et al., 2015; Chen et al., 2019; Távora et al., 2022).

4.3 RNA interference (RNAi) for gene silencing in maize

RNA interference (RNAi) is a powerful technique for gene silencing that involves the use of small RNA molecules to downregulate the expression of specific genes. In maize, RNAi has been utilized to suppress genes responsible for undesirable traits, thereby improving crop performance. This method allows for the targeted regulation of gene expression without altering the overall genome structure. RNAi has been particularly effective in enhancing resistance to pests and diseases, as well as improving stress tolerance and yield in maize (Rajput et al., 2021; Távora et al., 2022).

4.4 Applications of synthetic biology in maize breeding

Synthetic biology combines principles from engineering and biology to design and construct new biological parts, devices, and systems. In maize breeding, synthetic biology approaches have been used to create novel genetic circuits and pathways that can enhance crop traits. This includes the development of synthetic promoters, regulatory elements, and metabolic pathways to improve photosynthesis, nutrient use efficiency, and stress resilience. The integration of synthetic biology with traditional breeding and modern gene-editing techniques holds great promise for the future of maize breeding, enabling the creation of highly optimized and resilient crop varieties (Chen et al., 2019; Lorenzo et al., 2022; Ahmad, 2023). By leveraging these advanced genetic engineering techniques, researchers and breeders can accelerate the development of maize varieties that meet the growing demands for food security and sustainable agriculture.

5 Enhancing Agronomic Traits Through Genetic Engineering

5.1 Improving yield potential and stability

Genetic engineering has significantly contributed to improving the yield potential and stability of maize. By integrating advanced biotechnological approaches, such as transgenic technology and genome editing, researchers have been able to introduce genes that enhance yield under various environmental conditions. For instance, the discovery and field testing of over 3 331 DNA cassette constructs by Corteva Agriscience™ led to the identification of at least 22 validated gene leads that improved yield in elite maize breeding germplasm (Simmons et al., 2021). Additionally, the integration of doubled haploidy, high-throughput phenotyping, and genomics-assisted breeding has been crucial in developing elite maize cultivars with enhanced yield potential and stability, particularly in stress-prone environments (Prasanna et al., 2021).

5.2 Enhancing resistance to biotic stresses: pests and diseases

The development of maize varieties with enhanced resistance to biotic stresses, such as pests and diseases, is a critical aspect of genetic engineering. The International Maize and Wheat Improvement Center (CIMMYT) has been at the forefront of breeding maize with tolerance to key biotic stresses, deploying elite stress-tolerant maize cultivars across various regions (Figure 2) (Prasanna et al., 2021). Moreover, the identification and manipulation of stress-related genes through transgenic technology have led to the generation of maize plants with improved resistance to pests and diseases, thereby securing food production in the face of biotic challenges (Esmaeili et al., 2022).

Figure 2 Maize germplasm phenotyping/testing network of CIMMYT and partners in the tropics of ESA, Latin America, and Asia (Adopted from Prasanna et al., 2021)

5.3 Developing drought-tolerant and abiotic stress-resistant maize varieties

Drought tolerance and resistance to other abiotic stresses are vital traits for ensuring maize productivity in the face of climate change. Genetic engineering has played a pivotal role in developing drought-tolerant maize varieties. For example, the genetic dissection of drought tolerance through linkage and association mapping has provided insights into the molecular mechanisms underlying drought resistance, facilitating the development of drought-tolerant maize (Liu and Qin, 2021). Additionally, the use of quantitative trait locus (QTL) mapping and genome-wide association studies (GWAS) has enabled the identification of key genes associated with abiotic stress tolerance, which can be introgressed into maize varieties to enhance their resilience (Raj and Nadarajah, 2022). The successful deployment of drought-tolerant maize varieties in regions like Uganda has demonstrated their potential to mitigate the effects of drought and improve yield stability (Habte et al., 2023).

5.4 Nutritional enhancement and biofortification of maize

Nutritional enhancement and biofortification of maize through genetic engineering aim to address micronutrient deficiencies and improve the overall nutritional quality of maize. By introducing genes that enhance the biosynthesis of essential nutrients, researchers have been able to develop maize varieties with increased levels of vitamins and minerals. For instance, the integration of alleles associated with desirable agronomic traits, such as enhanced photoperiod and flowering traits, has the potential to improve the nutritional quality of maize (Dwivedi et al., 2017). Furthermore, the use of transgenic and gene editing technologies has enabled the manipulation of metabolic pathways to increase the content of specific nutrients, thereby contributing to the biofortification of maize (Esmaeili et al., 2022).

6 Environmental and Sustainability Impacts

6.1 Reducing the need for chemical inputs: herbicide tolerance and insect resistance

Genetic engineering has significantly contributed to reducing the need for chemical inputs in maize cultivation. For instance, genetically engineered (GE) maize varieties with herbicide tolerance and insect resistance have shown a marked decrease in the use of chemical pesticides. A meta-analysis revealed that the adoption of GE crops has led to a 37% reduction in chemical pesticide use, with insect-resistant crops showing more substantial reductions compared to herbicide-tolerant crops (Klümper and Qaim, 2014). Additionally, GE insect-resistant maize has been associated with an 11.2% reduction in insecticide use compared to non-GE varieties (Perry et al., 2016). These reductions not only lower production costs but also minimize the environmental impact of chemical inputs.

6.2 Genetic engineering and its potential role in climate-resilient agriculture

Genetic engineering plays a crucial role in developing climate-resilient maize varieties. Efforts by institutions like the International Maize and Wheat Improvement Center (CIMMYT) have led to the development of elite maize cultivars that can withstand various climate-induced stresses such as drought, heat, and salinity (Prasanna et al., 2021). These stress-tolerant varieties are essential for maintaining maize yields in the face of climate change, particularly in tropical rainfed environments. Furthermore, advancements in genomics-assisted breeding and genome editing technologies have accelerated the development of maize varieties with enhanced resilience to both biotic and abiotic stresses (Bisht et al., 2019; Thudi et al., 2020).

6.3 Environmental concerns: gene flow, biodiversity, and ecological balance

While genetic engineering offers numerous benefits, it also raises environmental concerns, particularly regarding gene flow, biodiversity, and ecological balance. The potential for gene flow from GE maize to wild relatives or non-GE crops could lead to unintended ecological consequences. However, studies have shown that GE maize hybrids do not pose additional risks compared to conventional maize in terms of pest potential or ecological impact (Díaz et al., 2016). Despite these findings, continuous monitoring and risk assessments are necessary to ensure that the cultivation of GE maize does not adversely affect biodiversity and ecological balance.

6.4 Potential for reducing the carbon footprint of maize cultivation

Genetic engineering has the potential to reduce the carbon footprint of maize cultivation by improving yield efficiency and reducing the need for chemical inputs. For example, transgenic maize varieties with enhanced tolerance to herbicides like dicamba allow for more effective weed control with fewer applications, thereby reducing fuel consumption and greenhouse gas emissions associated with chemical spraying. Additionally, the overexpression of certain genes, such as zmm28, has been shown to increase maize grain yield and improve nitrogen utilization, which can lead to more sustainable agricultural practices and lower carbon emissions (Wu et al., 2019). Overall, the integration of genetic engineering in maize breeding can contribute to more environmentally sustainable and climate-friendly agricultural systems.

7 Economic and Social Implications of Genetic Engineering in Maize

7.1 Cost-benefit analysis of genetically engineered maize for farmers

Genetically engineered (GE) maize has shown significant economic benefits for farmers, particularly in terms of increased yields and reduced pesticide use. A meta-analysis revealed that GE maize adoption has led to a 22% increase in crop yields and a 68% increase in farmer profits, while also reducing chemical pesticide use by 37% (Klümper and Qaim, 2014). These benefits are more pronounced in developing countries, where the technology has contributed to substantial welfare gains and poverty reduction. However, the initial costs of adopting GE maize, including the purchase of seeds and potential regulatory compliance, can be a barrier for small-scale farmers (Zilberman et al., 2018).

7.2 Impact on global maize markets and food supply chains

The introduction of GE maize has had a profound impact on global maize markets and food supply chains. The technology has enabled higher productivity and more efficient use of natural resources, which in turn has stabilized maize supply and prices in the global market. Developing countries, in particular, have adjusted their trade patterns to accommodate the preferences of major trading partners regarding GE and non-GE maize varieties. This adaptability has helped maintain market balance and ensured a steady food supply, although it has also introduced complexities in trade regulations and market segmentation (Sharma et al., 2022).

7.3 Public perception, consumer acceptance, and regulatory challenges

Public perception and consumer acceptance of GE maize vary widely across different regions. In some countries, GE crops are widely accepted and even welcomed by both farmers and consumers. However, in other regions, there are significant concerns about food safety and environmental impacts, leading to stringent regulatory frameworks (Zilberman et al., 2018). Overregulation can hinder the development and adoption of GE crops, resulting in missed opportunities for economic and social benefits, especially in developing countries. Effective communication and education about the benefits and risks of GE maize are crucial to improving public perception and acceptance (Klümper and Qaim, 2014; Ahanger et al., 2017).

7.4 Ethical considerations in genetically modifying staple crops like maize

The ethical considerations surrounding the genetic modification of staple crops like maize are multifaceted. On one hand, GE maize can contribute to food security and poverty alleviation by increasing crop yields and resilience to environmental stresses (Ahanger et al., 2017). On the other hand, there are concerns about the long-term ecological impacts, potential health risks, and the socio-economic implications for smallholder farmers who may become dependent on proprietary GE seeds (Hernández-Terán et al., 2017). Ethical debates also focus on the right to choose between GE and non-GE foods, the transparency of labeling, and the equitable distribution of the technology’s benefits (Zilberman et al., 2018; Sharma et al., 2022). Balancing these ethical considerations requires a nuanced approach that takes into account the diverse perspectives of all stakeholders involved.

8 Case Study: Bt Maize in the United States

8.1 Overview of the introduction and commercialization of Bt maize

Bt maize, a genetically engineered crop that produces insecticidal proteins from the bacterium Bacillus thuringiensis (Bt), was introduced in the United States in the mid-1990s. This innovation aimed to provide maize with inherent protection against major insect pests, such as the European corn borer and the western corn rootworm. The commercialization of Bt maize followed extensive research and development, which demonstrated its effectiveness in reducing pest damage and the need for chemical insecticides (Gassmann and Reisig, 2022). By 2 009, Bt maize constituted a significant portion of the U.S. maize crop, with over 22.2 million hectares planted, representing 63% of the total maize acreage.

8.2 Agronomic, economic, and environmental outcomes of Bt maize adoption

The adoption of Bt maize has led to several notable agronomic, economic, and environmental outcomes. Agronomically, Bt maize has significantly reduced crop damage from pests, leading to higher yields and more stable production (Gassmann and Reisig, 2022). Economically, the widespread use of Bt maize has resulted in substantial savings for farmers, both in terms of reduced insecticide costs and increased profits from higher yields. For instance, cumulative benefits over 14 years were estimated at $3.2 billion for maize growers in Illinois, Minnesota, and Wisconsin, with a significant portion of these benefits accruing to non-Bt maize growers due to regional pest suppression.

Environmentally, Bt maize has contributed to a reduction in the use of chemical insecticides, which has positive implications for non-target species and overall ecosystem health. Studies have shown that Bt crops support conservation biological control by reducing the need for synthetic insecticides, thereby fostering an environment conducive to natural enemies of pests (Romeis et al., 2019). Additionally, the regional suppression of pest populations due to Bt maize adoption has extended benefits to other crops, including vegetables, by reducing the overall pest pressure in the agricultural landscape (Dively et al., 2018).

8.3 Lessons learned from the deployment of genetically engineered maize

The deployment of Bt maize has provided several important lessons. One key lesson is the importance of integrated pest management (IPM) strategies to delay the development of pest resistance. The evolution of resistance in pests such as the western corn rootworm has highlighted the need for strategies that include refuges of non-Bt maize and crop rotation to manage resistance effectively (Table 1) (Gassmann, 2021; Gassmann and Reisig, 2022). Another lesson is the necessity of continuous monitoring and adaptive management to address emerging challenges and ensure the long-term sustainability of Bt technology (Gassmann, 2021).

Table 1 Studies testing for fitness costs of resistance to Bt maize by western corn rootworm (Adopted from Gassmann, 2021) Note: 1 Describes whether a strain was generated by selecting a susceptible stain on Bt maize in the laboratory (laboratory selected) or was generated from Bt-resistant insects collected from the field (field evolved). 2 Type of Bt maize on which the rootworm strain was selected and to which it was resistant. 3 States whether fitness costs of Bt resistant were detected for a specific strain in a study. 4 Life-history traits for which a fitness cost was detected or cases where resistance declined over time when a stain was not exposed to Bt maize (Adopted from Gassmann, 2021)

8.4 Scaling Bt maize technology in other regions and its global impact

Scaling Bt maize technology to other regions requires careful consideration of local agronomic conditions, pest pressures, and regulatory environments. The success of Bt maize in the United States provides a model for other countries, particularly in terms of the economic and environmental benefits. However, challenges such as resistance management and the need for robust regulatory frameworks must be addressed to ensure successful adoption (Meissle et al., 2014). Globally, the adoption of Bt maize has the potential to enhance food security by increasing maize yields and reducing losses due to pests, thereby contributing to more sustainable agricultural practices (Gouse et al., 2016).

9 Challenges and Limitations of Genetic Engineering in Maize Breeding

9.1 Regulatory hurdles and intellectual property concerns

The regulatory landscape for genetically engineered crops is complex and often fraught with delays and political interference. The process for regulatory approval is slow and costly, which can significantly hinder the commercialization of genetically modified maize varieties. For instance, the approval process for ‘Roundup Ready’ alfalfa in the US involved several rounds of regulation, deregulation, and re-regulation, illustrating the bureaucratic challenges faced by developers of genetically engineered crops. Additionally, the stringent regulatory requirements can be a major barrier to the adoption of new technologies, as seen in the limited commercialization of transgenic forage, turf, and bioenergy crops. Intellectual property concerns also pose significant challenges, as the proprietary nature of many genetic engineering technologies can limit access and increase costs for breeders and farmers (Herman et al., 2020).

9.2 Potential risks and unintended consequences: ecological and health concerns

Genetic engineering in maize breeding raises concerns about potential ecological and health risks. Unintended effects, such as changes in the transcriptome and metabolome, can occur, although studies have shown that these effects are often comparable to those observed in conventional breeding (Huang et al., 2022). However, the potential for unintended ecological impacts, such as gene flow to wild relatives and non-target effects on other organisms, remains a significant concern. Additionally, public fear and skepticism about the safety of genetically modified organisms (GMOs) can drive stringent regulatory oversight, further complicating the adoption of these technologies. Despite scientific consensus on the safety of transgenic breeding methods, these concerns must be addressed through rigorous risk assessment and transparent communication with the public (Herman et al., 2020).

9.3 Technical challenges in delivering precise genetic modifications

Achieving precise genetic modifications in maize is technically challenging. While advances in CRISPR/Cas9-mediated gene editing have shown promise, the complexity of traits governed by multiple small-effect genes requires sophisticated approaches to achieve desired outcomes. For example, the BREEDIT pipeline combines multiplex genome editing with crossing schemes to improve complex traits such as yield and drought tolerance, but this approach requires extensive gene discovery and validation efforts (Lorenzo et al., 2022). Additionally, the integration of genomic, bioinformatics, and phenomics tools is essential for optimizing breeding programs, but this requires significant investment in technology and expertise (Gedil and Menkir, 2019).

9.4 Socioeconomic barriers to adoption, particularly in developing countries

Socioeconomic barriers significantly impact the adoption of genetically engineered maize in developing countries. Issues such as limited access to technology, high costs of genetically modified seeds, and lack of infrastructure for effective implementation can hinder the widespread use of these innovations. Moreover, the capacity building of national agricultural research systems (NARS) is crucial for the smooth transfer of technologies and best practices, but this requires substantial investment and international collaboration (Gedil and Menkir, 2019). Additionally, public perception and acceptance of genetically modified crops can vary widely, influencing policy decisions and market dynamics (Herman et al., 2020). Addressing these barriers is essential for ensuring that the benefits of genetic engineering in maize breeding are accessible to farmers in developing regions.

10 Future Prospects for Maize Breeding

10.1 Integration of genetic engineering with other breeding technologies

The integration of genetic engineering with marker-assisted selection (MAS) and genomic selection (GS) holds significant promise for the future of maize breeding. Marker-assisted reverse breeding (MARB) is a notable example, which allows for the rapid recovery of beneficial parental genotypes from elite hybrids without the need for sophisticated transformation technologies (Guan et al., 2015). This method can be combined with GS, which uses genome-wide marker data to estimate breeding values, thereby accelerating the breeding cycle and increasing genetic gains (Crossa et al., 2017; Rice and Lipka, 2021). The combination of these technologies can enhance the efficiency of breeding programs by leveraging the strengths of each approach, such as the precision of MAS and the predictive power of GS.

10.2 Emerging technologies in maize breeding: gene drives, epigenetic modifications, and more

Emerging technologies such as gene drives and epigenetic modifications are poised to revolutionize maize breeding. Gene drives can propagate specific genetic traits through populations at an accelerated rate, offering a powerful tool for controlling pest resistance and other desirable traits. Epigenetic modifications, which involve changes in gene expression without altering the DNA sequence, can also play a crucial role in developing stress-tolerant and high-yielding maize varieties (Sethi et al., 2023). Additionally, advancements in genomic resources and sequencing technologies are enabling more precise trait mapping and the identification of candidate genes for targeted breeding (Ma et al., 2019; Thudi et al., 2020). These technologies, combined with traditional breeding methods, can significantly enhance the adaptability and productivity of maize.

10.3 The role of genetic engineering in ensuring global food security and sustainable agriculture

Genetic engineering is essential for ensuring global food security and promoting sustainable agriculture. By developing maize varieties that are resistant to biotic and abiotic stresses, genetic engineering can help stabilize yields and reduce the reliance on chemical inputs (Miedaner et al., 2020; Budhlakoti et al., 2022). For instance, genomics-assisted breeding has been instrumental in developing disease-resistant and climate-resilient maize varieties, which are crucial for maintaining food production in the face of climate change (Thudi et al., 2020). Furthermore, genetic engineering can contribute to the biofortification of maize, enhancing its nutritional value and addressing hidden hunger in vulnerable populations (Sethi et al., 2023). Overall, the integration of genetic engineering into maize breeding programs is vital for meeting the growing global demand for food in a sustainable manner.

10.4 Policy recommendations and research priorities for advancing maize breeding

To advance maize breeding, several policy recommendations and research priorities should be considered. First, increased funding and support for research in genetic engineering and related technologies are essential. This includes investments in high-throughput genotyping, phenotyping, and bioinformatics tools to facilitate the integration of MAS, GS, and other emerging technologies. Second, policies should promote the development of public-private partnerships to pool resources and expertise, ensuring that the benefits of advanced breeding technologies are widely accessible. Third, regulatory frameworks need to be updated to accommodate new breeding techniques, ensuring that they are safe and effective while also being flexible enough to encourage innovation (Guan et al., 2015). Finally, research should focus on understanding the genetic basis of complex traits and developing robust models for predicting breeding outcomes, which will be critical for the successful implementation of these technologies in maize breeding programs (Crossa et al., 2017; Rice and Lipka, 2021; Budhlakoti et al., 2022).

11 Concluding Remarks

Genetic engineering has revolutionized maize breeding by introducing advanced techniques such as CRISPR/Cas9-mediated genome editing, which allows for precise modifications of the maize genome to enhance desirable traits. These advancements have enabled the development of maize varieties with improved yield, drought tolerance, and resistance to pests and diseases. The integration of genomic tools, such as genome-wide association studies (GWAS) and quantitative trait loci (QTL) mapping, has further facilitated the identification of key genes and genetic markers associated with important agronomic traits.

The potential of genetic engineering to transform future maize production is immense. By leveraging technologies such as multiplex genome editing, researchers can simultaneously target multiple genes to improve complex traits like yield and stress tolerance. The development of genomic design breeding pipelines, which incorporate doubled haploid production, genomic selection, and genome optimization, promises to accelerate the breeding process and achieve maximum genetic gain with minimal resources. Additionally, the use of synthetic biology and the introduction of new biochemical pathways can lead to the creation of maize varieties with enhanced nutritional profiles and industrial applications.

The future of maize breeding lies in the continued integration of genetic engineering with traditional breeding methods. As the global population grows and climate change poses new challenges to agriculture, the ability to rapidly develop high-yielding, stress-tolerant maize varieties will be crucial for ensuring food security. The advancements in genetic engineering not only offer solutions to current agricultural challenges but also open up new possibilities for the sustainable production of maize. The ongoing research and development in this field will undoubtedly have significant implications for global agriculture, enhancing the resilience and productivity of maize crops worldwide.

Acknowledgments

GenBreed Publisher appreciates the two anonymous peer reviewers for their suggestions on the manuscript.

Conflict of Interest Disclosure

The authors affirm that this research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest.

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