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Drought and salinity are major abiotic stresses threatening global agriculture, necessitating resilient crop development. This review compares traditional breeding and genetic engineering approaches to enhance stress tolerance. Traditional methods—such as selection, hybridization, and marker-assisted breeding—have achieved moderate gains but are limited by complex trait inheritance and lengthy breeding cycles. In contrast, genetic engineering enables precise and rapid improvements through transgenic expression of stress-responsive genes (e.g., DREB, NHX1, Late Embryogenesis Abundant (LEA)) and genome-editing tools like CRISPR/Cas9. Key physiological and molecular responses include stomatal regulation, ion homeostasis, osmotic adjustment, and antioxidative defense. Field successes like MON 87460 maize and Bt cotton illustrate the potential of biotechnological interventions. This review emphasizes integrative strategies combining molecular genetics, genomic selection, and high-throughput phenotyping for effective crop improvement. While genetic engineering holds significant promise, it faces challenges related to technical constraints, regulations, and socio-ethical concerns, especially in developing countries. The review advocates a synergistic model that blends the strengths of conventional breeding with gene-editing precision to accelerate the creation of climate-resilient crops. This concise synthesis supports innovation in plant biotechnology to sustain agricultural productivity under escalating environmental stress.
Department of Sericulture, Raiganj University, Raiganj, West Bengal, India
Department of Botany, Hiralal Mazumdar Memorial College for Women, Kolkata, West Bengal, India
Madhushri Das Datta
Department of Botany, Hiralal Mazumdar Memorial College for Women, Kolkata, West Bengal, India
Debnirmalya Gangopadhyay
Department of Sericulture, Raiganj University, Raiganj, West Bengal, India
Shubhajit Shaw
Department of Sericulture, Raiganj University, Raiganj, West Bengal, India
Rahul Chatterjee
Department of Environmental Science, Indira Gandhi National Open University (Study Centre), Howrah, West Bengal, India
Ankita Manna
Department of Botany, University of Calcutta (Jogamaya Devi College Campus), Kolkata, West Bengal, India
*Address all correspondence to: rittik.acharya@gmail.com
1. Introduction
Climate change and increasing global food demands have underscored the urgent need for crops capable of withstanding challenging environmental conditions, particularly in arid and semi-arid regions where agricultural productivity is most vulnerable. Among the numerous abiotic stresses that threaten crop yields, drought and soil salinity are two of the most critical factors limiting agricultural output on a global scale [1, 2]. These stresses disrupt plant physiological and biochemical processes, ultimately reducing growth and productivity. Alarmingly, by 2050, it is projected that more than half of the world’s arable land could be severely affected by water scarcity and salinity stress [3]. This looming crisis poses a major threat to global food security, particularly in regions already facing food shortages. As conventional agricultural practices struggle to keep pace with these mounting environmental pressures, there is an increasing need to develop resilient crop varieties to withstand such stresses to achieve sustainable agriculture and long-term food security [4]. Figure 1 summarizes the impact of drought and salinity on stress-sensitive plants and highlights the superior performance of stress-tolerant plants under these adverse conditions.
Figure 1.
Impact of drought and salinity on stress-sensitive plants and the superior performance of stress-tolerance plants under these adverse conditions.
To address these challenges, traditional plant breeding methods have been used to enhance crop tolerance to drought and salinity. These strategies have yielded significant improvements in some crops [5]. However, conventional breeding is often a slow and labor-intensive process, constrained by the limited genetic variability available within a species [6]. The emergence of genetic engineering and molecular biotechnology has revolutionized crop improvement strategies. These advanced tools enable the direct manipulation of specific genes associated with stress responses, allowing for the development of genetically modified crops with enhanced tolerance to drought and salinity [7]. Such innovations hold immense potential for future agriculture.
This article delves into the significant advancements achieved through both traditional breeding and modern genetic engineering strategies aimed at enhancing drought and salt tolerance in crops. By critically examining and comparing their underlying methodologies, key achievements, limitations, and potential for large-scale application, we seek to offer a well-rounded and in-depth perspective. The discussion highlights how these approaches contribute to improving crop resilience under abiotic stress conditions and evaluates their roles and future prospects in promoting sustainable and climate-resilient agriculture.
2. Physiological and molecular mechanisms underlying plant tolerance to drought and salinity stresses
Plants have developed a sophisticated array of physiological and molecular strategies to survive drought and salinity, two major abiotic stresses that significantly constrain global agricultural productivity. These stresses disrupt water balance, ion homeostasis, and metabolic function, prompting plants to initiate multifaceted tolerance responses that span from whole-organism adjustments to molecular-level regulation.
At the physiological level, drought stress leads to a reduction in water availability, compelling plants to optimize water-use efficiency. A key mechanism involves the regulation of stomatal aperture through abscisic acid (ABA)-mediated signaling, which reduces transpiration-driven water loss [8]. Osmotic adjustment, achieved through the accumulation of compatible solutes such as proline, glycine betaine, and trehalose, helps maintain cellular turgor pressure and stabilizes proteins and membranes under water-deficient conditions [5]. The root system architecture also adapts to drought, with increased depth and density facilitating water uptake from deeper soil layers [9].
Under salt stress, plants face ionic toxicity and osmotic imbalance, primarily due to excessive sodium (Na+) uptake. To combat this, selective ion transport mechanisms restrict Na+ entry and sequester excess Na+ into vacuoles via Na+/H+ antiporters, thereby preserving cytoplasmic ion homeostasis [2]. Maintaining a high potassium-to-sodium (K+/Na+) ratio is crucial for sustaining enzymatic activity and metabolic functions [10].
Both drought and salinity also trigger the overproduction of reactive oxygen species (ROS), such as superoxide radicals and hydrogen peroxide, which cause oxidative damage to cellular components. In response, plants activate enzymatic antioxidant defenses, including superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX), which detoxify ROS and mitigate oxidative stress [11]. Photosynthetic efficiency is safeguarded through non-photochemical quenching and chloroplast-based antioxidant systems that minimize photodamage and maintain energy production under stress [12].
Central to these physiological defenses is the ABA signaling pathway, which not only regulates stomatal closure and osmotic adjustment but also interacts closely with ROS detoxification mechanisms. This crosstalk enables plants to orchestrate a coordinated stress response, integrating hormonal signaling with redox regulation. Transcription factors such as DREB and MYB serve as crucial mediators in this network, regulating the expression of stress-responsive genes involved in osmoprotection, antioxidative defense, and ion homeostasis [2].
On the molecular level, stress perception at the cell membrane activates complex intracellular signaling cascades. Secondary messengers, such as calcium ions (Ca2+), ROS, and phospholipids, initiate these responses by activating kinases, including mitogen-activated protein kinases (MAPKs) and calcium-dependent protein kinases (CDPKs), which in turn regulate downstream gene expression [11, 13]. Major transcription factor families—such as DREB, NAC, MYB, and bZIP—control the transcription of genes encoding osmoprotectants, ion transporters, and antioxidants [14]. Under drought, ABA biosynthesis and signaling genes, including NCED and AREB1, are upregulated to enhance tolerance through stomatal regulation and osmotic balance [15]. During salt stress, the Salt Overly Sensitive (SOS) pathway becomes crucial, with SOS1 functioning as a plasma membrane Na+/H+ antiporter that expels excess Na+ and maintains ionic equilibrium [16].
Additionally, gene expression is modulated post-transcriptionally by small RNAs, particularly microRNAs (miRNAs), which fine-tune stress responses by targeting mRNAs for degradation or translational inhibition [17]. Epigenetic modifications, including DNA methylation and histone acetylation, contribute further to stress adaptation by regulating chromatin structure and enabling stress memory, thereby priming plants for enhanced responses to recurrent stresses [18].
Collectively, these multilayered physiological and molecular mechanisms equip plants with the resilience necessary to survive environmental adversities. Deciphering these complex networks offers critical insights for crop improvement strategies aimed at enhancing stress tolerance in the face of ongoing climate change.
3. Breeding approaches for developing tolerant crops
Abiotic stresses, such as salinity and drought, significantly constrain global agricultural productivity, threatening food security under changing climatic conditions [19]. Developing crop varieties with enhanced tolerance to these stresses is therefore a critical objective in plant breeding programs. Conventional breeding, marker-assisted selection, and transgenic approaches have been employed to incorporate stress-tolerance traits into high-yielding cultivars [20, 21].
3.1 Traditional breeding methods
Traditional breeding techniques have been pivotal in developing crop varieties resilient to environmental stresses. These methods, which include selection, hybridization, and mutation breeding, aim to enhance stress tolerance by leveraging natural genetic variability. Selection involves identifying and propagating plants with desirable traits, such as drought tolerance or disease resistance, through iterative cycles over generations, leading to improved stress-resilient varieties. Hybridization, by crossing genetically diverse parental lines, combines advantageous traits to produce offspring with superior stress tolerance and performance. Mutation breeding, which employs chemical or radiation-induced mutagenesis, facilitates the emergence of novel traits—including enhanced stress tolerance—that are subsequently integrated into breeding programs [22, 23]. Collectively, these approaches have played a crucial role in advancing the development of drought- and salt-tolerant crop varieties, enabling farmers to combat the detrimental effects of water scarcity and soil salinity [24, 25].
3.2 Marker-assisted selection (MAS) and quantitative trait loci (QTL) mapping
Quantitative traits, such as those related to drought and salt tolerance, are typically governed by a complex interplay of genetic and environmental factors. The genomic regions controlling these traits, known as quantitative trait loci (QTLs), are specific segments of the genome associated with particular traits. Advances in molecular genetics have greatly facilitated the identification of QTLs, initially driven by the development of linkage maps in the 1980s. These maps enabled the generation of mapping populations and the identification of polymorphic markers, establishing critical linkages between molecular markers and QTLs [26].
Molecular markers, categorized into protein-based markers (e.g., isozymes) and DNA-based markers (e.g., RFLP, AFLP, SSR, and SNP), have proven instrumental in marker-assisted selection (MAS). MAS accelerates the breeding process by selecting favorable alleles, improving complex traits such as drought-related yield and difficult-to-measure traits like root architecture, water-use efficiency, and osmotic adjustment. Moreover, these markers facilitate the introgression of desirable traits from wild relatives, reducing linkage drag by minimizing the unintended co-transfer of undesirable genes [27].
Recent advancements extend beyond marker-based approaches to include gene identification strategies within QTL regions. Traditional map-based cloning is now complemented by high-throughput technologies such as microarray-based transcriptional profiling, which elucidates differential gene expression under stress conditions [28, 29]. Integrative approaches combining genetic mapping with expression profiling have further refined the identification of candidate genes associated with stress tolerance [30, 31]. For example, Huang et al. [32] identified approximately 2000 drought-responsive genes in Arabidopsis thaliana, with a significant proportion regulated by abscisic acid (ABA). Similarly, Seki et al. [33] reported 277 drought-responsive genes, many of which also respond to cold and heat stress, highlighting the overlap in abiotic stress responses.
QTL studies in crops such as wheat, rice, cotton, oilseeds, and forage species have underscored the utility of MAS for improving drought and salinity tolerance. Advanced backcross QTL analysis has also been employed to assess donor introgressions within elite genetic backgrounds, enhancing the efficiency of breeding programs [34]. Additionally, QTL mapping studies have identified numerous loci involved in salt stress responses [31, 35]. These developments underscore the transformative potential of molecular markers and integrative genomic approaches in accelerating the development of stress-tolerant crops, paving the way for sustained agricultural productivity under challenging environmental conditions [36].
4. Genetic engineering approaches for enhancing drought and salinity tolerance in crops
Genetically modified (GM) crops have emerged as powerful tools to combat the increasing threat of abiotic stresses such as drought and salinity. These crops are developed using precise genetic engineering techniques that involve the insertion of foreign genes into plant genomes through methods like Agrobacterium-mediated transformation or direct gene transfer, leading to the creation of transgenic plants [37]. Unlike traditional breeding, which is limited by species compatibility, genetic engineering allows the introduction of genes across taxonomic boundaries, thereby accelerating trait enhancement [38].
A major focus of genetic modification is improving tolerance to complex, multigenic stresses such as salinity and drought. Salt stress activates several physiological responses in plants, including osmolyte accumulation, activation of antioxidant systems, and regulation of ion homeostasis. Incorporating salt-tolerance genes from halophytes or modulating native stress-responsive genes enhances ionic regulation and stress signaling pathways. Notably, chloroplast-targeted expression of osmolyte biosynthetic genes has shown superior outcomes, indicating that subcellular localization plays a pivotal role in transgene performance [39, 40]. Similarly, the introduction of genes related to drought tolerance, such as those encoding transcription factors, aquaporins, Late Embryogenesis Abundant (LEA) proteins, and enzymes involved in osmolyte biosynthesis, has improved water-use efficiency and conferred protection against cellular dehydration [41, 42]. Prominent examples include MON 87460 maize and transgenic rice expressing CSPB, Ubi1::TPSP, and NHX1, which have demonstrated enhanced tolerance under field conditions, supporting their agricultural viability.
Improving abiotic stress resilience is critical for ensuring global food security amid escalating climate change impacts [43]. Molecular breeding and biotechnology have focused on manipulating key transcription factors such as DREBs [44] and on leveraging LEA proteins, which stabilize macromolecules under stress due to their hydrophilic and thermostable nature [41]. Genetic modification of ion transporters like HKT1 and NHX1 has also proven vital for salinity tolerance by maintaining ionic homeostasis [45, 46]. Further, enhancing the expression of heat shock proteins (Hsps) has been shown to improve thermotolerance in several crops, as demonstrated by Bhatnagar-Mathur et al. [7].
CRISPR/Cas9 genome editing has recently revolutionized crop improvement by allowing precise modifications of stress-related genes [47, 48]. For example, DREB transcription factors confer stress tolerance, but constitutive overexpression may cause growth defects. Using stress-inducible or tissue-specific promoters allows for localized expression, mitigating growth penalties while maintaining stress resilience [40]. In soybean, overexpression of DREB1A improved drought response in greenhouse conditions through reduced water use, although field yields remained unchanged [44, 49].
LEA proteins, initially identified in seeds, have been recognized for their protective roles in vegetative tissues under abiotic stress. They are grouped into seven subfamilies and are highly expressed across plant genomes: 51 genes in Arabidopsis, 34 in rice, 108 in Brassica napus, and 23 in Phyllostachys edulis [50, 51]. Transgenic expression of wheat-derived group I and II LEA genes (PMA1959, PMA80) in rice enhanced drought and salinity tolerance [52], while OsEm1 upregulated other LEA genes under stress [53]. Group II proteins, such as RAB16A and SmLEA2, improved antioxidant defenses [54, 55], and group III members, such as HVA1 and OsG3LEA-47.3, imparted combined drought and heat tolerance [56, 57]. Additionally, atypical group V proteins, such as AdLEA from Arachis diogoi, enhanced multiple stress tolerances in tobacco [58].
Sodium transporters play a pivotal role in salinity stress responses. In rice, OsHKT1;1 restricts Na+ accumulation in shoots and is regulated by the MYB-type transcription factor OsMYBc, which binds directly to its promoter. Mutants lacking OsMYBc show diminished OsHKT1;1 expression and increased salt sensitivity [45]. Similarly, vacuolar sequestration via NHX1 and cytoplasmic Na+ efflux by SOS1 work synergistically to maintain Na+/K+ balance. Individually, these transporters are insufficient under high salinity (>200 mM NaCl), but co-expression of AtNHX1 and AtSOS1 in Arabidopsis allowed tolerance up to 250 mM NaCl with no yield loss [46].
The heat shock response is orchestrated by heat shock transcription factors (HSFs), which become activated upon stress and promote the expression of Hsps that stabilize proteins and form stress granules [7, 59, 60, 61, 62]. This response is increasingly harnessed in transgenic plants to improve thermotolerance.
Salinity disrupts nutrient balance, membrane function, and photosynthesis due to elevated Na+ and Cl− [63, 64, 65], which plants counter through ion transporters and reactive oxygen species detoxification [2]. CRISPR/Cas9 offers a precise solution to these challenges. As illustrated in Figure 2, CRISPR/Cas9 enables targeted knockouts or overexpression of genes related to drought and salinity tolerance, allowing fine-tuned genetic interventions. Examples include overexpression of SOS1 and HvHKT2;1 in Arabidopsis and barley for enhanced Na+ transport [66, 67]. In rice, CRISPR knockouts of OsRR22, OsPQT3, and OsmiR535 improve salt stress tolerance [47, 68]. Similarly, editing SlHyPRP1 in tomato and ACQOS in Arabidopsis boosts stress resilience [48, 69]. Drought tolerance is polygenic and difficult to improve through traditional methods [70, 71]. CRISPR addresses this by modifying genes such as DERF1, MYB5, SPP, OST2, and miR169a in rice and Arabidopsis [72, 73], as well as ARGOS8, abh2, and ERA1 in cereals [74, 75, 76, 77]. Successes in rapeseed, wheat, tomato, and cotton validate CRISPR’s broad applicability in engineering climate-resilient crops [78, 79]. A summary of major CRISPR-mediated improvements in abiotic stress tolerance is presented in Table 1.
Figure 2.
The mechanism of CRISPR/Cas9-mediated development of drought and salt tolerance in plants.
Plant
Targeted gene(s)
Gene function
Target trait
Reference
Rice
DERF1, PMS3, MSH1, MYB5, SPP
Involved in amino acid biosynthesis and regulation of drought-responsive genes; enhances tolerance via metabolic adaptation and stress-responsive transcription.
Significant CRISPR/Cas9 mediated drought and salinity tolerance enhancement.
Source: Compiled by the authors.
Further, pangenome analysis, gene stacking, and synthetic biology represent cutting-edge strategies in the development of drought- and salinity-tolerant plants. Pangenome analysis allows for the comprehensive exploration of genetic diversity across cultivated and wild relatives, facilitating the identification of novel alleles associated with osmotic adjustment, ion homeostasis, and stress signaling [95]. These unique alleles can then be targeted for introgression through marker-assisted backcrossing or genome editing to enhance stress resilience. Gene stacking, or pyramiding, involves the combination of multiple genes or quantitative trait loci (QTLs) that regulate different facets of stress response, such as osmoprotectant biosynthesis, antioxidative defense, and ion transport. This approach has been shown to produce crops with broader and more stable tolerance to multiple abiotic stresses [96]. In parallel, synthetic biology offers the potential to engineer entirely novel regulatory circuits and metabolic pathways not found in nature. For instance, the construction of synthetic osmoregulatory networks or stress-inducible gene modules in model plants has demonstrated enhanced adaptation under extreme environmental conditions [97]. While still largely in the experimental phase, these integrative technologies significantly expand the toolkit for developing climate-resilient crops and hold promise for future agricultural sustainability.
5. Practical outcomes of genetic engineering for drought and salt tolerance
Traditional breeding has long enhanced crop resilience by selecting tolerant cultivars through crossbreeding and exploiting natural genetic variability, as seen in India’s development of salt- and drought-tolerant rice [98, 99]. However, this approach is time-intensive and limited by the gene pool’s diversity. In contrast, genetic engineering enables precise and rapid modification of stress-related genes, exemplified by transgenic crops such as Bt cotton and drought-tolerant maize [49, 100]. Advances like CRISPR-Cas9 further allow targeted, foreign DNA-free edits, as demonstrated in drought- and salt-resistant tomato and rice [101]. While genetic engineering offers speed and specificity, traditional breeding garners broader acceptance. Integrating both strategies with genomics-assisted tools presents a robust pathway to sustainable agricultural resilience [102].
5.1 Successful GM and transgenic crops
The intensifying impacts of climate change, notably water scarcity and soil salinization, have propelled the development of genetically engineered crops with enhanced stress tolerance [103]. Biotechnological strategies aimed at increasing salt tolerance and water-use efficiency (WUE) are crucial for maintaining crop productivity under adverse conditions [104]. Table 2 outlines various significant experiments on drought- and salt-tolerant crops. Drought-tolerant maize (MON 87460), engineered with the Bacillus subtilis cspB gene, enhances WUE by stabilizing proteins and photosynthetic structures under water deficit [117]. Bt cotton, initially designed for pest resistance, also improves drought tolerance via better stomatal regulation and root architecture [118]. Transgenic rice expressing AtNHX1 facilitates vacuolar Na+ sequestration, maintaining ionic balance under salinity stress [119], while tomatoes overexpressing SlNCED1 increase abscisic acid, promoting osmotic balance and stomatal closure [120]. In cotton, transgenic stacking of HVA1 and DREB enhances osmotic adjustment and photosynthetic efficiency under drought, achieving up to 30% higher lint yields while maintaining fiber quality [121, 122, 123]. These traits demonstrate the value of combining biotic and abiotic resistance [124], though biosafety, regulatory approval, and public acceptance remain essential [125]. CRISPR/Cas9-based editing of ARGOS8 in maize reduces ethylene sensitivity, delaying senescence and boosting biomass without yield penalties [126, 127], exemplifying integrated molecular strategies for climate-resilient agriculture [128].
Crop
Genotypes studied
Number of genotypes
Nature of salinity stressor
Nature of study
Parameters studied
Trait targeted
Method used
Key outcomes
Reference
Bt Cotton
Bt cotton hybrids
3
Salinity
Field trials across India
Yield, pest resistance
Salt tolerance and pest resistance
Genetic modification (Bt gene insertion)
Bt cotton showed increased yield and reduced pesticide use under saline conditions.
Significant transgenic experiments to develop drought and salinity tolerance in different crop varieties.
Source: Compiled by the authors.
5.2 Field performance and adoption of genetically modified (GM) crops
Genetically modified (GM) crops offer several agronomic and nutritional benefits, including herbicide tolerance, insect resistance, abiotic stress tolerance, disease resistance, and enhanced nutritional content [38]. Bt cotton, a leading example, has significantly reduced pesticide use and improved yields and profitability in countries like China and India [129, 130]. Similarly, Bt soybean and Bt maize have achieved effective pest control in North America [131]. GM crops with herbicide tolerance, such as glyphosate-resistant maize and soybean, lower labor costs and soil degradation by minimizing tillage [132]. Nutritionally enhanced GM crops, such as Golden Rice, address deficiencies such as vitamin A shortage [133]. However, public skepticism and regulatory constraints—especially stringent in Europe—hinder broader adoption [134, 135]. While GM crops show exceptional field performance in North and South America, concerns over resistance development, gene flow, and biodiversity impacts continue to shape their global acceptance and future deployment [136].
6. Comparing breeding and genetic engineering approaches
Traditional plant breeding and genetic engineering are two pivotal strategies for enhancing drought and salinity tolerance in crops. Conventional breeding involves selecting and crossing naturally stress-tolerant varieties to combine beneficial traits. This method has yielded notable successes, such as the development of salt-tolerant rice and wheat lines. However, its effectiveness is limited by the availability of genetic diversity, sexual compatibility barriers, and the complexity of traits such as drought and salinity tolerance, which are often controlled by multiple genes [137, 138]. Moreover, the long breeding cycles and potential for linkage drag make this approach time-consuming and less precise.
In contrast, genetic engineering enables the direct introduction or modification of specific genes associated with stress tolerance, bypassing species barriers. Key advances include the incorporation of genes encoding transcription factors such as DREB, Late Embryogenesis Abundant (LEA) proteins, and ion transporters like NHX1 and HKT1, which have demonstrated enhanced osmotic adjustment, ion homeostasis, and cellular protection under stress conditions [41, 44, 45, 46]. Moreover, using stress-inducible and tissue-specific promoters helps mitigate adverse effects on plant growth by restricting transgene expression to relevant conditions or tissues [139].
While breeding remains vital for integrating multiple traits into elite germplasm, genetic engineering offers complementary precision and speed essential for tackling complex, multigenic stress responses in a changing climate. Table 3 outlines the key distinctions between traditional breeding and genetic engineering approaches in the development of stress-tolerant plants.
Criteria
Traditional breeding
Genetic engineering
Reference
Definition
Crossing of organisms with desirable traits through sexual reproduction.
Direct manipulation of an organism’s DNA to introduce or alter traits.
Outlines the key distinctions between traditional breeding and genetic engineering approaches in developing drought and salinity-stress-tolerant plants.
The development of stress-resilient crops requires a comprehensive strategy that integrates conventional breeding with advanced genetic engineering methodologies. As illustrated in Table 4, several examples highlight the synergistic use of these approaches in developing drought- and salinity-tolerant plant varieties. Conventional breeding techniques, such as hybridization and selection, continue to play a pivotal role in exploiting naturally occurring genetic diversity within elite germplasm. Nevertheless, the efficiency of these methods is constrained by prolonged breeding cycles and the intricate genetic architecture of abiotic stress tolerance, particularly due to the multigenic nature of traits like drought and salinity resistance [103, 162].
Strategy/Approach
Description
Examples
Advantages
Limitations
References
Conventional breeding
Selection and hybridization of drought/salt-tolerant genotypes over generations.
An account of the prominent studies on breeding and genetic engineering together for drought and salinity tolerance in crops.
Source: Compiled by the authors.
Recent advances in genome editing, particularly CRISPR/Cas9, have enabled precise, targeted modifications of stress-responsive genes involved in ionic homeostasis and osmoprotectant synthesis, facilitating the rapid development of superior allelic variants [163]. CRISPR-edited rice and maize lines have demonstrated enhanced physiological responses under stress, including up to 30% improved water-use efficiency and a 25% reduction in sodium accumulation compared to non-edited counterparts [50, 114].
Integrating genetic engineering with hybrid breeding is further strengthened by high-throughput phenotyping and genomic prediction models, which help assess allele performance across diverse genotypes [164]. Pangenomic analyses of wild relatives provide access to untapped alleles for traits like osmotic adjustment, which can be fine-mapped and introgressed via marker-assisted backcrossing or targeted editing [95].
Collaborative platforms uniting public and private sectors enable shared phenotyping protocols and germplasm development, while machine learning algorithms optimize hybrid × gene-editing strategies. Together, these integrated methodologies have boosted drought tolerance gains by up to 40% in key crops such as wheat and cotton [165].
8. Challenges and considerations in the deployment of genetically modified crops
The development of genetically modified (GM) crops with enhanced tolerance to drought and salinity represents a promising strategy to strengthen global food security amid intensifying environmental stresses. Engineered through sophisticated molecular technologies, these crops offer precise interventions to improve plant resilience under adverse conditions. However, their widespread adoption is accompanied by several ecological, regulatory, and socio-economic challenges. A major ecological concern involves the potential for transgene flow to wild relatives, which may unintentionally introduce novel traits into natural ecosystems, thereby disrupting ecological balance and affecting non-target organisms [166, 167]. Furthermore, interactions between GM crops and various biotic components—such as pests, pollinators, and beneficial soil microbes—require rigorous ecological risk assessments to evaluate long-term environmental impacts. It is also critical to recognize the disparity between laboratory success and real-world performance, as many transgenic lines that exhibit stress tolerance under controlled conditions encounter limitations in field environments due to complex environmental interactions and regulatory constraints. Several notable examples illustrating these challenges are summarized in Table 5.
Crop
Transgene(s)
Laboratory Outcomes
Field Performance
Reference
Wheat (HB4)
HaHB4 (from sunflower)
Enhanced drought tolerance; delayed senescence
Approved in Argentina (2020), Brazil (2021), USA (2022); increased yield under drought
An account of laboratory success and practical field application, where many transgenic crops face environmental and regulatory screening.
Source: Compiled by the authors.
On the regulatory front, global frameworks remain fragmented. Countries differ significantly in how they classify and manage GMOs, particularly with the advent of gene-editing technologies such as CRISPR-Cas9. In the United States, a relatively permissive regulatory approach distinguishes between transgenic organisms and gene-edited crops lacking foreign DNA, often exempting the latter from stringent oversight and thereby facilitating their commercial release [174]. Conversely, the European Union adopts a more cautious stance. The European Court of Justice ruled in 2018 that all gene-edited organisms fall under existing GMO legislation, irrespective of the presence of foreign DNA [175]. In contrast, countries such as Argentina, Brazil, and Japan have adopted more nuanced frameworks, exempting CRISPR-edited crops from GMO regulations when modifications mimic natural mutations and no transgenes are introduced [176].
Beyond regulation, social acceptance remains a challenge. Despite scientific consensus on GM crop safety, public skepticism persists due to perceived health risks, environmental impacts, and ethical concerns [134]. Addressing these issues requires transparent governance, robust public engagement, and science-based communication strategies. Economically, the high costs associated with developing GM crops—including investment in gene-editing tools, rigorous testing, regulatory approvals, and necessary infrastructure—can restrict access for smallholder farmers, particularly in developing regions [177]. This economic barrier risks exacerbating existing inequalities in agricultural productivity and technological adoption [178].
Thus, while GM crops and genome-edited technologies hold substantial potential to enhance crop resilience and agricultural sustainability, their broader success hinges on the implementation of integrative strategies that balance innovation with ecological safety, regulatory coherence, equitable access, and public trust.
The escalating impacts of climate change and the need to sustain a growing global population have highlighted the urgency of developing drought- and salt-tolerant crops. While traditional breeding has contributed to crop resilience, its slow pace and difficulty in combining multiple traits limit its effectiveness. The integration of biotechnology, particularly genetic engineering, has significantly enhanced breeding precision by enabling the targeted incorporation of genes associated with drought and salt tolerance [179]. Innovations such as CRISPR-Cas9 have further refined genome editing, allowing for precise trait introduction with minimal off-target effects compared to conventional methods [71]. These advances are pivotal in addressing climate-induced challenges and ensuring food security. Additionally, precision agriculture—combining biotechnology with data-driven tools such as remote sensing and soil moisture sensors—enables site-specific crop management, improving yield and sustainability [179]. The rapid development of gene-editing technologies and gene synthesis platforms also facilitates the design of stress-resilient crops tailored to local environments, ushering in an era of personalized agriculture [180]. Together, these integrated approaches offer transformative potential for cultivating climate-resilient crops and securing global food systems in an uncertain environmental future.
The escalating impacts of climate change, including intensified drought and soil salinization, present significant threats to agricultural sustainability and global food security. This review examines the physiological, molecular, and genetic mechanisms underlying plant responses to abiotic stress and assesses the effectiveness of both conventional breeding and modern genetic engineering in developing drought- and salt-tolerant crops. Traditional breeding, though widely utilized, is hindered by the slow integration of traits, polygenic complexity, and limited genetic diversity. In contrast, genetic engineering—particularly transgenic approaches and CRISPR/Cas9 genome editing—has enabled precise modification of key stress-responsive genes, enhancing water-use efficiency, ion regulation, and antioxidative responses. Successful examples include drought-tolerant maize (MON 87460) and salinity-tolerant rice expressing AtNHX1. However, the broader adoption of genetically modified crops remains challenged by technical, regulatory, and ethical concerns, such as rigorous biosafety protocols, public resistance, and limited access in low-resource regions. The review underscores the promise of integrative strategies combining traditional and molecular techniques, supported by genomics, high-throughput phenotyping, and predictive modeling, to accelerate breeding outcomes. As climate pressures intensify, future efforts must prioritize interdisciplinary collaboration, transparent regulation, and equitable innovation. Ultimately, a harmonized approach merging genetic precision with conventional resilience offers the most sustainable path toward climate-resilient agriculture.
Acknowledgments
The authors are grateful to the Hon’ble Vice Chancellor of Raiganj University and the Hon’ble Principal, Hiralal Mazumdar College for Women, India, for providing the necessary facilities. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Conflict of interest
The authors declare no conflict of interest.
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Written By
Ritwik Acharya, Madhushri Das Datta, Debnirmalya Gangopadhyay, Shubhajit Shaw, Rahul Chatterjee and Ankita Manna
Submitted: 08 May 2025Reviewed: 20 May 2025Published: 07 July 2025
Open access peer-reviewed chapter - ONLINE FIRST
