Mutation Breeding as a Tool for Sustainable Crop Production and Climate Resilience: Experiences from the South-Eastern Europe (SEE) and Central Asia (CA)

Abstract

The review summarizes practical experiences in using mutation breeding for crop improvement in South-Eastern Europe (SEE) and Central Asia (CA), demonstrating that mutation breeding can be a field-validated, effective approach for developing climate-resilient crops. Drawing on coordinated research conducted within national breeding programs and international initiatives supported by FAO/IAEA, applied methodologies, trait-evaluation strategies, and concrete breeding outputs in cereals, legumes, and industrial crops are presented. The use of gamma irradiation, fast neutrons, and chemical mutagens has successfully generated stable mutant lines stable mutant lines with enhanced traits, such as increased thousand-grain weight in wheat, altered oil quality in sunflower, and improved drought tolerance in common bean and sesame. The integration of classical pedigree selection with modern breeding tools such as high-throughput phenotyping, molecular and biochemical markers, and doubled-haploid technology has enabled earlier and more efficient identification of superior genotypes in mutation breeding programs. The review underscores the practical relevance of mutation breeding in contemporary pipelines to maintain yield stability and quality under adverse environmental conditions.

1. Introduction

Mutation breeding is a globally recognized approach for generating novel allelic variation in crops through chemical or physical mutagenesis, which increases mutation frequency far above the spontaneous background level (by 1000 to 1 million-fold), thereby enriching the genetic variation available for crop improvement [1]. By expanding the genetic base in ways conventional breeding cannot easily achieve, mutation breeding has become an important complementary strategy for crop improvement [2]. Since its practical application in the 1960s, mutation breeding has evolved alongside advances in molecular biology, progressively integrating tools such as marker-assisted selection (MAS) and transposon mutagenesis for achieving more targeted selection of desirable traits [1]. So far, worldwide, induced mutagenesis has made a substantial contribution to crop improvement, with more than 3460 released mutant varieties across cereals, oil crops, legumes, vegetables, and fruit species, as documented in the FAO/IAEA Mutant Variety Database [3]. These varieties have delivered significant gains in yield, quality, stress tolerance, and resistance to pests and diseases, highlighting the importance of mutation breeding as a complementary strategy to conventional and molecular breeding approaches [4,5,6].

South-Eastern Europe (SEE) countries, together with parts of Central Asia (CA), are characterized by highly diverse, yet increasingly challenging climate conditions for agricultural production, encompassing continental, Mediterranean, and mountainous zones. These conditions strongly influence crop selection, yields, and risk management, and are characterized by diverse production systems, a strong reliance on major field crops such as wheat, maize, sunflower, and grain legumes, and a wide range of vegetable species [7]. Agriculture in these regions plays a critical role in food security, rural employment, and export-oriented production [8] (Burkitbayeva et al. 2021). However, crop productivity is increasingly affected by climate change, as evidenced by rising average temperatures, more frequent and intense droughts, irregular precipitation patterns, and progressive soil degradation [9]. Climate projections suggest that the continental climate of the Pannonian zone, covering Hungary, Croatia, Serbia, Bulgaria, and Romania, will experience the most severe negative impacts on agricultural production. In this region, more frequent heat waves and droughts will occur, with no effective means to shift crop cultivation to other seasons [10]. In southern Europe (North Macedonia, Greece and Türkiye), particularly large decreases in yield are expected for spring-sown crops (e.g., maize, sunflower and soybeans) due to long-lasting drought periods [11]. Similarly, climate change projections for CA indicate significant risks to agricultural production, with rising temperatures and altered precipitation expected to reduce crop yields and increase yield variability across the region [12].

Beyond environmental constraints, genetic limitations have also restricted breeding progress in several major crops cultivated in the SEE and CA regions. Domestication bottlenecks, genetic drift, and prolonged use of narrow breeding germplasm pools have reduced genetic diversity and adaptability, particularly for complex traits such as drought tolerance and stress resilience [13,14]. These constraints have limited the potential for further genetic gain from existing variation, especially under rapidly changing climatic conditions. In this context, mutation breeding provides an effective strategy to overcome genetic stagnation by inducing novel allelic variation and restoring adaptive potential within elite and locally adapted germplasm [15,16]. Unlike wide hybridization or conventional selection methods, induced mutagenesis allows the generation of new traits while preserving the favorable genetic background of well-adapted varieties, making it particularly relevant for regional breeding programs in SEE and CA. When integrated with modern tools such as MAS, high-throughput phenotyping, TILLING, and genomic technologies, mutation breeding can significantly accelerate the development of climate-resilient and high-yielding crop varieties [5,17].

Although mutation breeding has been widely reviewed at the global and crop-specific levels, the experience, achievements, and future prospects of mutation breeding in South-Eastern Europe and Central Asia have not previously been synthesized. This review addresses that gap by integrating evidence across countries, crops, breeding strategies, and emerging technologies to identify effective approaches and future research priorities for climate-resilient crop improvement. It also provides integrated analysis of mutation breeding programs across SEE and CA, linking mutagenesis protocols, high-throughput physiological phenotyping, and concrete mutant outputs to climate resilience breeding pipelines under regional stress scenarios. The review highlights the methodologies applied in national programs, breeding achievements across cereals, legumes, and industrial crops, and evaluates the role of physiological phenotyping and molecular tools in accelerating selection efficiency. Finally, it identifies future priorities for strengthening mutation breeding as a regional strategy for climateresilient crop improvement, situating the collective experience of SEE and CA within the broader global context of sustainable agriculture under climate change.

2. SEE and CA Mutation Breeding Material: Background

To address the urgent challenges posed by climate change, IAEA supported two regional projects (RER/5/024 and RER/5/030) and brought together researchers from breeding institutions in SEE and parts of CA. The breeding institutions involved have a long tradition in crop breeding, supported by national agricultural research institutes, universities, and public breeding programs focusing on cereals, legumes and industrial crops (

Table 1. Participating countries, leading institutes, and principal crops addressed in the study.

Country	Institution	Major Crops Used for Mutagenesis	References
Bosnia and Herzegovina	Institute of Genetic Resources of University of Banja Luka; Faculty of Agriculture and Food Sciences, University of Sarajevo	Wheat, common bean	[25,27]
Bulgaria	Agricultural Academy, Maritsa Vegetable Crops Research Institute, Plovdiv	Common bean	[18,28,29]
Croatia	Faculty of Agriculture, University of Zagreb	Common bean, wheat	[26]
Greece	Department of Crop Science, Agricultural University of Athens; Aristotle University of Thessaloniki; Institute of Industrial & Forage Plants, Hellenic Agricultural Organization “DIMITRA”, Larissa	Pea, Sesame	[22,30,31,32]
North Macedonia	Department of Genetics and Plant Breeding, Faculty of Agricultural Sciences and Food, Skopje	Wheat, common bean	[20,33,34,35,36]
Türkiye	Turkish Energy Nuclear and Mineral Research Agency; Nuclear Energy Research Institute, Ankara	Wheat, barley	[19,37,38]
Poland	University of Silesia, Katowice	Buckwheat	[21]
Serbia	Institute of Field and Vegetable Crops, Novi Sad	Wheat, sunflower	[23,39,40,41,42]
Uzbekistan	Institute of Genetics of the Academy of Sciences; Institute of Plant Genetic Resources of the Ministry of Agriculture	Wheat, cotton	[24,43]

). The landscape of mutation breeding across SEE and CA is characterized by significant heterogeneity in breeding systems and objectives, as well as maturity levels of mutation breeding programs. Regional leaders are Bulgaria and Türkiye with long-standing records of high-impact mutant variety releases, obtained by combining classical and modern breeding tools, particularly in cereals and vegetables [18,19]. Although there are no registered mutant varieties in Greece, North Macedonia, Poland and Serbia, the research teams developed “fixed” lines in M6 generation or higher using classical and multi-omics approaches for mutant population evaluations [20,21,22,23]. Other nations such as Bosnia and Herzegovina, Croatia and Uzbekistan are leveraging international technical cooperation to establish their systematic yield trials and genetic screening protocols [24,25,26]. This regional diversity is further defined by specialized breeding objectives, where Mediterranean nations like Greece prioritize legumes and some specific industrial crops, while programs in Uzbekistan (CA) focus on abiotic stress tolerance in cotton and wheat. Despite these varying points of departure, there is an increasing regional convergence toward climate-smart agriculture, facilitated by collaborative networks that synchronize traditional mutagenesis with modern genomic selection tools. Mutation breeding experiments were conducted across multiple countries using a range of crop species, including wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), buckwheat (Fagopyrum sp.), pea (Pisum sativum L.), common bean (Phaseolus vulgaris L.), sunflower (Helianthus annuus L.), sesame (Sesamum indicum L.) and cotton (Gossypium hirsutum L.).

3. Mutation Breeding: Methodology and Trait Evaluation

3.1. Methodology

Optimizing mutagenic treatments is a critical step in mutation breeding, ensuring that sufficient genetic variability is induced without compromising population viability. Approaches such as LD₅₀ (Lethal Dose 50%), GR₅₀ (Growth Reduction 50%), and EMD₅₀ (Effective Mutation Dose 50%) provide quantitative benchmarks for balancing mutagenic efficiency with plant survival and growth, and have been applied across diverse crops and countries in SEE and CA. Physical mutagenesis using gamma irradiation was the primary approach across all countries, while fast neutrons and chemical mutagens (

Table 2. Comparative overview of mutagen types and doses, over crops and countries.

Country	Crop/Species (Varieties)	Mutagen Type	Dose Range	Predominant Mutation Aims	References
Türkiye	Wheat (‘Karahan-99’, ‘Tosunbey’), Barley (‘Tokak 157/37’)	γ-rays (Co60)	100–800 Gy (optimal ≈ 150–300 Gy) EMD50-based	Chromosomal rearrangements affecting yield, drought and disease tolerance	[19,37,38]
Uzbekistan	Winter wheat (‘Alexievich’, ’Edgu’)	γ-rays (Co60)	75–300 Gy	Increased yield performance and drought tolerance	[24]
Uzbekistan	Cotton	γ-rays (Co60)	100 to 500 Gy	Beneficial hormetic effects	[43]
Serbia	Wheat (‘NS40S’, ‘Rudnik’, ‘Simonida’)	γ-rays (Co60)	75–600 Gy (GR50 ≈ 210–310 Gy)	Broaden adaptive capacity to climatic conditions	[39,41]
Serbia	Sunflower	γ-rays (Co60) FN EMS	70–500 Gy 3–50 Gy 0.1–2.5% (3.5 h)	Altered morphological and phenological traits	[23,40,42]
Greece	Field pea (‘Dodoni’, ‘Early Onward’, ‘Rondo’)	γ-rays (Co60)	100 Gy (LD50)	Increased yield, nutritional value and resilience	[31,32]
Greece	Sesame	γ-rays (Co60)	150 to 350 Gy	Drought tolerance	[22]
Bosnia & Herzegovina	Winter wheat (‘Nova Bosanka’)	γ-rays (Co60)	150, 200 & 300 Gy	Improved key productivity and adaptability traits	[25]
Bosnia & Herzegovina	Common bean	γ-rays (Co60)	80 & 200 Gy	Quantitative and qualitative trait mutations	[27]
North Macedonia	Wheat (8 commercial varieties)	γ-rays (Co60)	200 & 300 Gy	Improved yield, quality, disease and drought resistance	[20,33,34,35]
North Macedonia	Common bean	γ-rays (Co60)	80, 120 & 160 Gy	Improved productivity and resilience	[36]
Croatia	Winter wheat (‘Barba’)	γ-rays (Co60)	250 & 300 Gy	Better understanding of adaptive responses	-
Croatia	Common bean (‘Biser’ ‘Trešnjevac’, ‘Zelenčec’)	γ-rays (Co60)	100 & 150 Gy	Study of stress tolerance mechanisms Development of more resilient cropping systems	[26]
Bulgaria	Common bean	EMS	6.2 mM	Improved yield-related traits and resistance/tolerance	[18,28,29]
Poland	Buckwheat (F. esculentum Moench var. ‘Panda’ and ‘Kora’, and F. tataricum (L.))	γ-rays (Co60); MNU	0, 75, 150, 300, 450, and 600 Gy; 1, 2, 3, 4 mM	Enhanced nutritional properties	[21]

) were also used in sunflower breeding programs in Serbia [44].

Gamma irradiation (γ-rays), using Co⁶⁰ sources, was the predominant mutagenic treatment across SEE and CA, with dose selection guided by radiosensitivity assays and the estimation of LD₅₀, GR₅₀, or EMD₅₀ values (Table 2). In addition to gamma irradiation, irradiation with fast neutrons (FN) were also applied in sunflower breeding programs in Serbia, with dose selection based on LD₃₀ and LD₅₀ values reported in previous studies. Prior to irradiation, seed moisture was equilibrated to ensure uniform treatment effects [40,44].

As for chemical mutagens such as ethyl-methane-sulphonate (EMS) and nitroso-methyl-urea (MNU), they required careful optimization of concentration, exposure time, and seed hydration status. In Bulgaria, EMS treatments were applied at concentrations ranging from 1.55 to 24.8 mM for six hours at ambient temperature with gentle shaking, using 1% methanol as a solvent [28]. In Serbia, sunflower seeds were treated with EMS at concentrations between 0.1 and 2.5%, alongside gamma rays and fast neutrons, with dose selection again guided by LD₃₀ and LD₅₀ values [40,44].

Mutagenic treatments were generally conducted at specialized irradiation facilities, including the Joint FAO/IAEA Laboratories in Seibersdorf (Austria), national nuclear research institutes, or authorized gamma facilities. Experimental designs, population sizes, selection strategies, and trait evaluations were harmonized across crops while accounting for species- and genotype-specific responses to mutagenic treatments (Table 2). In Bulgaria, mutation breeding programs have followed standardized protocols for induced mutagenesis and the selection of stabilized mutant lines [18]. In Türkiye, from the M₃ stage onwards, the main lines were established from selected mutant individuals, showing superior traits compared to the control, and the classical breeding stages were followed by evaluation of the agricultural traits in the selected lines until the M₇ stage [45] (Figure 1).

3.2. Trait Evaluation

3.2.1. Cereals

Wheat

Wheat mutation breeding programs were implemented in North Macedonia, Bosnia and Herzegovina, Serbia, Croatia, Türkiye, and Uzbekistan using irradiation for mutation induction (Table 2). Treated seeds were used to establish M₁ populations, which varied from several hundred to over 30,000 plants depending on the experiment. M₁ plants were generally grown without selection and self-pollinated, and seeds were harvested on a single-plant basis to generate M₂ progenies. From the M₂ generation onwards, selection was performed using classical pedigree methods, with selection intensity increasing in later generations [45]. In North Macedonia, selection extended to advanced generations (M₆–M₁₀) [20], while in Bosnia and Herzegovina, Serbia and Uzbekistan evaluations were conducted up to the M₄ generation [27,41].

Trait evaluation focused on agronomic performance, yield and yield components, quality traits (protein content, sedimentation value, gluten strength, and HMW glutenin composition), phenology (heading, flowering, and maturity), plant height, lodging resistance, and resistance to major fungal diseases, including Septoria, yellow rust, leaf rust, Pyrenophora, powdery mildew, and Fusarium culmorum [37,41,46]. Abiotic stress tolerance, particularly drought tolerance, was evaluated under both field and controlled conditions [20,33,34,35]. Field evaluation was performed in Uzbekistan, where irradiated seeds of the winter wheat varieties ‘Alexievich’ and ‘Edgu’ were grown in optimal growing conditions and simulated drought stress. Early generations (M₁–M₂) showed reduced growth with increasing irradiation dose, but certain groups exhibited larger spikes, higher thousand-grain weight, increased pigment content, and relative tolerance to drought and yellow rust. Selection was carried out across three generations based on yield performance and stress tolerance. In Türkiye, drought response was assessed using polyethylene glycol (PEG 6000, BASF, Ludwigshafen, Germany)-induced osmotic stress [19,38]. Physiological traits such as chlorophyll content, anthocyanins, flavonols, normalized difference vegetation index (NDVI) and nitrogen balance index (NBI) were measured in some programs using non-destructive optical sensors [41].

Molecular and biochemical characterization complemented phenotypic selection. Protein markers, SSRs, SNP markers, and gliadin electrophoresis were used for quality assessment and mutant identification, while advanced programs incorporated doubled-haploid production via anther culture to accelerate the fixation of desirable mutations [19,24].

Barley

Barley mutant populations were developed through classical mutation breeding from M₁ to M₇ [45]. Agronomic, morphological, and yield-related traits were evaluated under field conditions, while drought tolerance and disease resistance were assessed using controlled laboratory and greenhouse assays. Selected mutant lines were further subjected to anther culture to produce genetically stable doubled haploid lines [37,47].

Buckwheat

Seeds of F. esculentum Moench var. ‘Panda’ and ‘Kora’, and F. tataricum (L.) Gaertn. were used as a source of material for mutagenesis. Gamma radiation for seeds was applied at the following doses: 0, 75, 150, 300, 450, and 600 Gy. Also, chemical mutagenesis was used with nitroso-methyl-urea (MNU; 1, 2, 3, 4 mM). Trait evaluation of M₃ in controlled greenhouse conditions focused on morphological assessment, yield and carotenoid concentration [21].

3.2.2. Legumes

Pea

Mutation breeding in field pea was conducted in Greece using gamma irradiation to induce genetic variability in forage and vegetable pea varieties ‘Dodoni ’, ‘Early Onward’, ‘Ron-do ’. In M₁ generation, gamma irradiation did not significantly affect plant height, number of shoots, or leaf number in ‘Dodoni’. In contrast, significant reductions in these traits were observed in the more sensitive varieties ‘Early Onward’ and ‘Rondo’. No statistically significant differences in pod and seed number per plant were detected across varieties [31].

Based on M₁ performance, the M₂ generation focused primarily on the variety ‘Dodoni’, with fewer families from ‘Early Onward’. M₂ families were grown using an augmented incomplete block design, and selection was based on vegetative growth, flowering characteristics, pod traits, seed number, and biomass-related parameters. The ‘Dodoni’-derived mutant families showed superior performance and stability compared with the other varieties. Moreover, disease response was quantified using an ex-planta leaf bioassay with Didymella pinodes, in which lesion development was measured using ImageJ-based digital analysis on the 3rd and 5th days post-inoculation [32].

Common Bean

Mutation breeding in common bean was carried out in Bulgaria, North Macedonia and Bosnia and Herzegovina using gamma irradiation. Seeds of advanced breeding lines and reference varieties were exposed to two doses, 80 and 200 Gy [25]. Large M₁ populations were established, with several thousand plants evaluated for survival and reproductive ability. Seeds from individual M₁ plants were advanced to M₂ populations, where selection focused on yield-related traits, disease resistance, and drought tolerance. Experimental trials were established to evaluate plant responses to selected abiotic stress conditions, with particular emphasis on physiological performance and stress-induced functional adjustments. Advanced phenotyping approaches were employed, including chlorophyll fluorescence imaging, multispectral analysis, and morphological assessments, enabling a comprehensive evaluation of plant status under controlled conditions. These efforts aimed to improve the understanding of stress tolerance mechanisms and support the development of more resilient cropping systems.

In Croatia, early-generation (M₁, M₂) physiological responses to gamma irradiation were assessed in three traditional common bean varieties (‘Trešnjevac’, ‘Biser’, and ‘Zelenčec’) grown under greenhouse conditions. Seeds were exposed to 100 and 150 Gy, after which chlorophyll fluorescence and multispectral imaging were applied to characterize photosynthetic performance. Clear genotype-specific responses were observed, indicating differential sensitivity to irradiation dose. Lower irradiation (100 Gy) generally enhanced several fluorescence parameters in ‘Biser’ and ‘Trešnjevac’, whereas ‘Zelenčec’ exhibited stronger responses at 150 Gy. The maximum quantum yield of PSII (Fv/Fm) displayed dose-dependent variation among genotypes, underscoring the complexity of physiological adjustments following mutagenic treatment. Among multispectral traits, saturation was the only parameter that responded consistently, increasing at the higher dose in two varieties [26].

In Bulgaria, seed from ‘Evros’ variety was used for the treatment with 6.2 mM ethyl-methane-sulfonate (EMS) [28] and five mutants marked as M4, M8, M11, M19 and M26 were developed [29].

3.2.3. Industrial Crops

Sunflower

Treated sunflower seeds using both physical and chemical mutagenesis were grown under greenhouse and field conditions together with untreated control seeds to assess radiosensitivity based on seedling height reduction. M₁ plants were self-pollinated, and pedigree selection was applied from the M₂ generation onwards. Selection criteria included plant height, flowering time, branching pattern, head diameter, seed yield, and oil content and quality. The stability of desirable traits was verified across multiple generations (M₄–M₇) through replicated field trials conducted in randomized block designs [23,42].

Sesame

Twenty-three elite sesame lines were used for mutagenic treatment in Greece in order to enhance drought tolerance in sesame [22]. Seeds were exposed to gamma-irradiation (150 to 350 Gy) producing a large M₁ population. For each M₁ plant, 2–5 capsules were harvested individually from the main stem circumference [48].

Cotton

Cotton mutation breeding in Uzbekistan has been revitalized to broaden the genetic base of cotton and improve fiber quality under challenging climatic conditions. Medium-fiber cotton varieties with diverse fiber colors, including light brown, dark brown, cream, golden, and green, were irradiated before sowing at doses ranging from 100 to 500 Gy using gamma rays [43]. The mutant populations displayed clear dose-dependent variability in boll number and fiber traits. At lower doses (100–150 Gy), a stimulatory effect was observed, with slight increases or stability in boll number, while higher doses (200–300 Gy) reduced boll formation [43]. These results highlight the sensitivity of cotton varieties to radiation and the potential of low-dose irradiation to induce beneficial hormetic effects.

4. Mutation Breeding Achievements in the SEE and CA: Overview

Mutation breeding in SEE and CA has evolved along diverse trajectories, reflecting the different traditions and starting points of national programs. In Bosnia and Herzegovina, crops such as wheat and common bean have already progressed to the M₄ generation, while mutation breeding in countries such as Serbia, North Macedonia, Türkiye, Greece, and Uzbekistan is generally at more advanced stages, though progress varies by crop. For example, in Serbia wheat mutation breeding has reached the M₄ generation, whereas sunflower programs have advanced to mutant varieties. This illustrates that across SEE and CA, national programs are at different stages depending on the crop, but most have moved beyond the initial phases and achieved stable mutant lines suitable for further breeding. Historical milestones include the initiation of mutation breeding programs in Greece and Serbia in the late 1960s, followed by the establishment of similar programs in Uzbekistan in the 1970s and in Türkiye in the early 1980s, with many released mutant varieties [49,50,51]. Together, these activities demonstrate the region’s growing capacity to integrate mutation breeding into crop improvement pipelines, despite infrastructural and funding limitations, and provide a strong basis for strengthening mutual cooperation. In recent years, in the framework of various initiatives, including the IAEA project RER/5/024, participating institutions have built on these foundations by combining mutation breeding with modern molecular tools to develop climate-resilient varieties of major food crops. This review presents the contemporary collective efforts and achievements in mutation breeding across SEE and CA, highlighting progress in crop improvement and resilience (Figure 2).

4.1. Cereals

Cereals represent a major focus of mutation breeding programs across SEE and CA, reflecting their central role in food security and climate resilience. Wheat and barley have been the primary targets, with mutagenesis generating substantial variability in morphological, physiological, and stress-related traits.

Mutation breeding has produced striking diversity in wheat spike morphology and pigmentation. From awnless reference varieties, mutant lines have emerged with awns, altered spike coloration (gold and pink), exceptionally dense and elongated spikes, and enhanced chlorophyll content. In Serbia, the first measurements were performed in the wheat M₄ generation comprising 200 lines in the open field (Figure 3).

Analyzed traits included: plant height, spike and peduncle length, presence or absence of awns and phenological traits, such as heading and flowering time. Further investigations in the next generations will be important for confirming and assessing the stability of the observed differences. In 50 M₄ wheat lines, differences in physiological parameters, such as chlorophyll, anthocyanins, and nitrogen balance index (NBI), were recorded [41]. In Bosnia and Herzegovina (Banja Luka), mutation breeding programs in wheat have demonstrated that gamma irradiation induces clear dose-dependent effects on mutant line survival and phenotypic variability in the M₃ generation of winter wheat. Higher irradiation doses reduced survival rates but increased mutagenic effectiveness. Nevertheless, the highest dose (300 Gy) substantially increased phenotypic variability and enabled the identification of extremely high-yielding lines and genotypes that combine elevated spike number with high productivity. The moderate dose of 200 Gy provided a favorable balance between induced variability and population size, while 300 Gy produced the most promising elite mutants. These findings confirm the value of induced mutagenesis as an effective strategy for broadening genetic variability and selecting superior lines in early generations of wheat breeding [27].

In North Macedonia, wheat mutation breeding programs have focused on a broad range of agronomic and quality traits. Trait evaluation was conducted through detailed phenotypic characterization, with improvements monitored and maintained over successive generations using both positive and negative selection [20,33,35]. Protein quality was further analyzed using biochemical assays and SSR markers, providing molecular confirmation of variation within the mutant populations [34].

In Croatia, research was conducted on winter wheat to evaluate crop responses to abiotic stress conditions relevant to regional agroecological conditions. Experimental trials were conducted under field conditions. The objective of these activities was to strengthen the understanding of adaptive responses in winter wheat and contribute to the development of more resilient cereal production systems under increasing environmental variability.

Mutation breeding in Türkiye has been applied extensively to wheat and barley, two crops of major national importance. Seeds of the bread wheat varieties ‘Karahan-99’ and ‘Tosunbey’, as well as the barley variety ‘Tokak 157/37’, were irradiated with gamma rays from a Co⁶⁰ gamma source to generate mutant populations. Trait evaluation in barley mutants revealed variation in plant height, spike length, spike type and density, anthocyanin accumulation, sterile spikelet development, and heading time. Yield-related traits such as grain yield, thousand-kernel weight, and hectoliter weight were also assessed, alongside kernel size distribution. 85 selected mutant barley lines were further subjected to anther culture, yielding doubled-haploid (DH) lines. These DH lines exhibited higher grain yield, reduced plant height, and improved lodging resistance compared with self-pollinated controls (

Table 3. Mean values of agronomic and quality traits of barley mutant lines and commercial varieties (Peşkircioğlu et al. 2024 [37]).

Mutant	Plant Height (cm)	Spike Length (cm)	Physical Traits	Grain Yield (kg ha−1)	1000-Grain Weight (g)	Hectoliter Weight (kg hL−1)	Sieve > at 2.5 mm (%)
‘Tokak 157/37’ (Control)	100	7–9	Drought tolerant	577–971	49	70	77
2 N	140	9–10	Non logging	518–3876	50	65	62
12 N	80–90	9–10	Earliness, dwarf	520–3716	50	70	84
21 T	140	10–11	Dwarf	448–3022	57	69	76

) [37]. This demonstrates the efficiency of combining mutation breeding with DH technology to stabilize elite lines, which was also previously reported [47,52,53].

In wheat, disease resistance was evaluated against Fusarium culmorum using virulent isolates from Central Anatolia. Genotypes displayed a wide range of responses, from highly susceptible to moderately resistant. Moderately resistant lines, including ‘Altay 2000’, ‘BW5’, and ‘E-5/6’ mutants, showed lower disease severity and stable reaction profiles, making them valuable donors for breeding programs [54].

Furthermore, drought tolerance was assessed using polyethylene glycol (PEG 6000) to simulate osmotic stress at multiple levels [19,38]. PEG-induced osmotic stress significantly reduced seedling growth, biomass accumulation, and root development, with clear genotypic differences observed. Genotypes that maintain higher root length and biomass under stress conditions are considered more drought-tolerant. Strong positive correlations were observed among germination rate, root length, root number, seedling height, and leaf sheath length, while biomass traits showed negative correlations with elongation growth. Principal component analysis (PCA) identified divergent mutants such as ‘Köse 220/39’ and ‘TSB 256’, which exhibited distinct physiological responses under stress. Based on these analyses, three strategic three-way breeding combinations were proposed to maximize genetic diversity and enhance drought tolerance, integrating both traditional varieties and mutant lines [19]. These achievements underscore the potential of mutation breeding, particularly when combined with advanced techniques such as anther culture and multivariate analysis, to accelerate the development of climate-resilient and disease-resistant cereal varieties in Türkiye [55,56,57].

In Uzbekistan, from the total number of mutant forms of the two varieties, ‘Aliksyevich’ and ‘Yog’du’, M₃ plants with different grain and ear weights and resistance to yellow rust were selected. Seventeen forms were selected from the optimal background and 18 from artificial drought. Fifteen forms were selected for their relative resistance to yellow rust. The mutant forms were evaluated for physiological and biochemical parameters, resistance, yield and stability of useful properties. Protein and gluten content analyses confirmed variability among irradiation treatments, with several mutant lines demonstrating improved nutritional parameters under drought conditions. These selected lines are suitable for propagation as new varieties or as donors in breeding programs. By the M₄ generation, ten wheat genotypes from the two varieties were identified as promising, showing phenotypic uniformity and stability in yield and quality. Protein and gluten content analyses confirmed variability among irradiation treatments, with several mutant lines demonstrating improved nutritional parameters under drought conditions [24]. These selected lines are suitable for propagation as new varieties or as donors in breeding programs.

Mutation breeding of buckwheat resulted in increased seed yield and carotenoid content. Gamma irradiation resulted yield enhancement of 26% in M₃ generation, while chemical treatment of 1 mM MNU resulted higher carotenoid content level in M₃ generation.

4.2. Legumes

Mutation breeding offers a powerful tool to expand the genetic base of legumes, generating novel traits that strengthen their role in sustainable crop production and climate resilience. Recent initiatives in SEE and CA illustrate this potential, with mutation breeding applied to common bean and pea to improve yield components, disease resistance, and stress tolerance. These case studies highlight how legumes can serve as models for integrating mutation breeding into regional strategies for climate adaptation and food security.

4.2.1. Pea

In Greece, three varieties were used for mutagenesis [58] and subjected to gamma irradiation to evaluate seed yield, quality traits (protein and mineral content: Fe, Zn, Mn, Cu), and tolerance to Didymella pinodes, the causal agent of ascochyta blight. Several individual plants displayed superior reproductive performance, with pod and seed yields exceeding controls by more than twofold. Five families were identified as promising candidates for advancement to the M₃ generation [31]. Biochemical analyses of selected families demonstrated increased protein content, higher Fe and Zn concentrations, and enhanced antioxidant activity, while protease activity remained stable. These findings indicate that gamma irradiation can generate pea mutants with improved nutritional and biofunctional properties (Sarri et al., personal communication). Disease tolerance assays using detached-leaf bioassays against Didymella pinodes identified families with reduced disease severity, particularly ‘DMIV21’, ‘DMIV36’, and ‘DMIV49’, which combined tolerance with improved yield traits [32]. Conversely, some families exhibited increased susceptibility, underscoring the complexity of mutagenic effects. This work represents one of the first comprehensive applications of gamma irradiation in pea breeding, integrating agronomic, biochemical, and disease resistance evaluations. The results highlight both opportunities and trade-offs, consistent with antagonistic pleiotropy, and emphasize the need for balanced selection strategies. The families identified in this study provide a functional framework for developing nutritionally enhanced, environmentally resilient pea varieties, contributing to sustainable agriculture and food security.

4.2.2. Common Bean

In Bosnia and Herzegovina (Banja Luka), seeds of a bush-type common bean reference variety were irradiated with two gamma doses. By the M₄ generation, phenotypic evaluation revealed mutant lines with climbing growth habit, diverse flower coloration, seed coat colour changes [25]. Also, longer pods, higher seed number per pod and improved disease resistance were observed. These modifications expand the genetic base of common bean and provide valuable donor lines for breeding programs aimed at enhancing adaptation and resilience under changing climatic conditions.

In North Macedonia, evaluation through successive generations up to M₄ revealed improvements in seed yield and yield-contributing traits, as well as enhanced disease resistance and abiotic stress tolerance. Detailed trait assessments included plant height, pod length and width, seed length and width, hundred-seed weight, seeds per pod, days to flowering, and seed yield per plant. Observations of disease tolerance and drought stress tolerance further confirmed the potential of these mutants as donors for breeding programs [36].

In Bulgaria, a total of 70 M₈ mutant lines with diverse altered traits have been developed through induced mutagenesis of elite varieties. These advanced lines represent stabilized material suitable for detailed phenotypic, molecular, and agronomic evaluation.

4.3. Industrial Crops

4.3.1. Sunflower

Sunflower is one of the most important oilseed crops in SEE, widely cultivated for its high-quality edible oil and valuable by-products. Several distinct mutant types were identified in the mutation breeding program in Serbia. Early-flowering mutants such as line ‘Early-1’ (derived from fast neutron treatment of line ‘L3’) flowered approximately five days earlier than the original line without affecting plant height, demonstrating separation of traits typically correlated in sunflower. Short-stature mutants (‘Shorty-5’ and ‘Shorty-9’) were obtained with gamma irradiation (100–120 Gy). ‘Shorty-5’ was 15 cm shorter than its tall parent line ‘L2’ yet produced significantly higher seed yield per plant, while ‘Shorty-9’ (from restorer line ‘R1’) showed variability in flowering time and head size. Reduced plant height is considered advantageous for standability and yield stability, as confirmed in ‘Shorty-5’. Conversely, a high-stature mutant, ‘Tally-2’, was produced by gamma irradiation (200 Gy) of the dwarf line ‘R3’, resulting in plants 30 cm taller, with longer vegetation, larger heads, and higher seed yield, traits favorable for hybrid production [44].

Mutants with enhanced oil content were also identified. ‘Oily-3’ (fast neutrons, 3 Gy) and ‘Oily-7’ (gamma irradiation of line ‘R2’) exhibited increased and stable oil percentages compared to their parental lines. Oil content reached 49.7% in ‘Oily-3’ and 46.1% in ‘Oily-7’, compared to 44.6% and 36.0% in the respective controls. While mutation-induced changes in sunflower oil content are generally modest, these results demonstrate that targeted mutagenesis can generate lines with improved oil yield and stability [44].

Concerning oil quality, in the M₂ generation, seeds were analyzed for fatty acid composition, and individual plants showed noticeable alterations. In the following generation, a putative mutant line (‘ML31-1’) was identified, exhibiting significantly reduced oleic acid content compared with the high-oleic line ‘L31’ grown in the same season [59]. Further molecular studies showed that mutant progeny with reduced oleic acid content still preserved the Ol mutation in at least one allele and valuable source for further breeding [60].

4.3.2. Sesame

In Greece, a long-term breeding program aims to identify superior sesame genetic resources to support the expansion and modernization of sesame cultivation. Over six years of evaluating Greek sesame landraces, elite progeny lines were selected, but a narrow genetic base was identified, limiting further breeding progress—particularly for traits needed in modern, mechanized production systems [61] (Figure 4).

Figure 4. Sesame field experiment for drought tolerance. Approximately 600 M₂ progeny rows established in two environments (full and 40% reduced irrigation). Plants exhibit contrasting canopy development and biomass accumulation under limited water availability. Plots maintaining greater green leaf area and canopy density indicate superior drought resilience through enhanced water acquisition, efficient water use, delayed senescence, and sustained photosynthetic activity. Such field phenotyping trials enable the identification of resilient germplasm for climate-adaptive crop improvement.

Figure 4. Sesame field experiment for drought tolerance. Approximately 600 M₂ progeny rows established in two environments (full and 40% reduced irrigation). Plants exhibit contrasting canopy development and biomass accumulation under limited water availability. Plots maintaining greater green leaf area and canopy density indicate superior drought resilience through enhanced water acquisition, efficient water use, delayed senescence, and sustained photosynthetic activity. Such field phenotyping trials enable the identification of resilient germplasm for climate-adaptive crop improvement.

Developing climate-resilient mutant sesame is a strategic approach to overcome the narrow genetic base identified in existing germplasm and to enhance the crop’s adaptability to changing environmental conditions [48]. A rigorous composite index was developed to assess capsule shattering based on three components: the number of seeds retained in an upright mature capsule, seed retention after capsule inversion, and the percentage of capsule opening. This multi-criteria approach enabled reliable identification of stable, non-shattering mutant lines, leading to the selection of approximately 50 genotypes combining strong drought tolerance with traits suitable for mechanized cultivation [62]. These genotypes will form M₃ families for further evaluation using an augmented incomplete block design, while the ongoing mutagenesis and selection program will be enhanced by modern genomic tools and high-throughput phenotyping to generate valuable pre-breeding material and support the development of high-yielding, climate-resilient sesame varieties.

4.3.3. Cotton

Morphological and technological traits expressed in the mutant populations revealed the degree of genetic responsiveness of the studied fiber-colored genotypes. Among them, green-, golden-, and cream-fiber mutants demonstrated high stability and yield potential, making them valuable donors for breeding programs [43]. Their incorporation into breeding pipelines is expected to diversify fiber quality, enhance resilience, and contribute to the development of cotton varieties adapted to the arid and semi-arid conditions of CA. Current work continues to evaluate these radio-mutants for yield stability and technological properties, with the long-term objective of releasing improved varieties and integrating them into national breeding strategies.

5. Discussion

Agricultural production in SEE and CA has been challenged by extreme environmental conditions. One of the solutions is induced mutagenesis, which is not only a source of theoretical variability, but a practical breeding tool for climate adaptation. In the particular regions, mutant-derived varieties could demonstrate improved yield and quality parameters, enhanced drought and heat tolerance, improved stress physiology, and greater disease resistance under field conditions [63]. Such traits could contribute to yield maintenance and stability across variable environments. Therefore, the development and deployment of mutant-derived varieties would represent a field-validated strategy to strengthen climate resilience, food security, and production sustainability in climate-vulnerable regions such as SEE and CA.

5.1. Physiological Phenotyping as a Catalyst for Accelerating Mutation Breeding

After induced mutagenesis it is very important to choose an adequate method for traits evaluation. A major bottleneck in mutation breeding and early-generation selection is that many adaptive traits (drought/heat/disease tolerance) are physiologically complex and often poorly captured by morphological scoring alone, while strong genotype × environment interactions can mask true genetic differences. Integrating high-throughput physiological phenotyping into mutation-breeding pipelines can therefore increase selection efficiency by providing rapid, non-destructive, and more objective proxies of stress response that are measurable on large populations and at relevant developmental stages. Across crops and stress types, canopy temperature has emerged as one of the most robust predictors of stress performance, reflecting water relations and stomatal regulation; it shows high utility in early-generation selection and can deliver measurable genetic gain under drought/heat when deployed in appropriately timed field screening [64,65,66]. Moreover, combining canopy-temperature–related phenotypes with genomic selection frameworks can substantially improve prediction accuracy compared with genomics alone, highlighting the complementary information content of physiological traits [65].

Chlorophyll fluorescence and spectral approaches add mechanistic resolution and are particularly valuable for detecting early functional shifts in photosynthetic performance that may precede visible symptoms, but their predictive value depends on stress type, intensity, and duration. For example, chlorophyll fluorescence has been shown to differentiate tolerant vs. susceptible responses under prolonged drought in some crops [67] and to provide informative predictors of heat/drought response in wheat when appropriate parameters and stress regimes are used [68]. In contrast, limited predictive power can occur in highly plastic species or under transient stress conditions, emphasizing the need for context-specific validation and measurement timing aligned with critical stress-sensitive windows [68,69]. For resource-limited programs typical of parts of SEE and CA, a tiered strategy is therefore pragmatic: use scalable traits such as canopy temperature and spectral indices for initial screening, then apply fluorescence imaging and targeted gas exchange on a reduced subset for deeper physiological characterization and decision support [64,65,70]. Such an approach aligns well with the goal of accelerating early enrichment of mutant populations before advanced multi-location testing and can strengthen the deployment of mutation breeding as a modern, physiology-informed tool for climate resilience.

5.2. Practical Use of New Cereal Mutant Varieties as Climate-Resilient Crops

Mutation breeding has significantly contributed to wheat improvement worldwide and played an important role during the Green Revolution by generating valuable genetic variability for yield and adaptation [71]. Several mutation-derived varieties have achieved large-scale adoption and delivered substantial economic benefits. Mutation-derived varieties such as ‘Jauhar-78’, ‘Soghat-90’, and ‘Kiran-95’ in Pakistan demonstrated high yield potential, improved grain quality, and disease tolerance, collectively contributing over US $87 million to farmer income during the 1990s [72]. The Indian variety ‘Sharbati Sonora’, a mutant of ‘Sonora 64’, also gained widespread acceptance due to improved grain quality during the early years of the Green Revolution.

Our findings from SEE and CA demonstrate that induced mutagenesis continues to generate useful variability for modern wheat breeding. Gamma-induced mutant genotypes developed in Serbia, Bosnia and Herzegovina, North Macedonia, Türkiye, and Uzbekistan showed increased spike number, higher thousand-grain weight, and enhanced variability in yield components, particularly at moderate-to-high irradiation doses in field conditions [27,39]. Importantly, several lines maintained stable protein and gluten content under drought conditions in field trials [24], which is essential in continental production regions where terminal drought and heat stress frequently reduce grain filling and grain quality. Physiological analyses revealed variation in chlorophyll content, anthocyanin accumulation, and nitrogen balance index among field-grown mutant lines [41], suggesting improved photosynthetic stability and stress-response mechanisms. Because canopy temperature regulation and sustained photosynthetic activity are strongly associated with drought adaptation [64,65], these mutants represent promising material for rainfed and marginal environments. In addition, the identification of varieties with moderate resistance to Fusarium culmorum in Türkiye highlights the potential for simultaneous tolerance to both abiotic and biotic stresses under climate change scenarios. The need for diversified genetic resistance sources is further emphasized by the threat of ‘Ug99‘, first detected in Uganda, which remains one of the most serious global risks to wheat production due to widespread variety susceptibility.

Mutation breeding has made major contributions to barley improvement, particularly through the development of semi-dwarf varieties that enhanced yield stability and lodging resistance. Two of the most influential examples are ‘Diamant’ and ‘Golden Promise’, which had a profound impact on European barley production and the malting and brewing industries. ‘Diamant’, released in 1965 in Czechoslovakia after gamma irradiation of the variety ‘Valticky’, was about 15 cm shorter and produced approximately 12% higher grain yield. Its genetic background was subsequently incorporated into more than 150 barley varieties grown across Europe, North America, and Asia, largely due to the beneficial semi-dwarf denso gene that improved lodging resistance and productivity [73]. Likewise, ‘Golden Promise’, developed through gamma irradiation of the variety ‘Maythorpe’, combined short stature, stiff straw, high yield, and excellent malting quality, making it widely used by breweries in the United Kingdom and Ireland and contributing substantially to the brewing and whisky industries [74].

Recent mutation breeding efforts continue to demonstrate the relevance of this approach for climate-resilient barley improvement. In Türkiye, gamma-induced mutant lines with reduced plant height and improved lodging resistance showed favorable agronomic performance under field conditions [37]. Reduced plant height is particularly advantageous under increasingly frequent extreme rainfall and storm events in continental climates. Early-heading mutants can also escape terminal heat and drought stress, a widely recognized adaptive strategy in cereals [65]. When combined with doubled-haploid technology to accelerate genetic stabilization [47], these mutants can rapidly contribute to the development of barley varieties adapted to variable and climate-stressed production environments.

5.3. Pea and Bean as Models for Integrating Resilience, Productivity, and Nutritional Quality

In legumes, pea provides a clear example of how induced mutagenesis can simultaneously contribute to productivity, disease tolerance, and improved crop architecture. Early achievements in mutation breeding demonstrated how specific architectural traits can improve agronomic performance. For instance, the gamma-ray-induced mutant variety ‘Wasata‘, released in Poland in 1979, carried the afila (tendrilled leaf) trait in which leaflets are converted into tendrils while stipules remain functional. This plant architecture improves canopy aeration, light penetration, and standing ability, facilitating mechanical harvesting and reducing lodging. The afila trait was subsequently incorporated into breeding programs, leading to semi-leafless pea varieties are now widely cultivated in many countries, demonstrating the long-term breeding value of induced architectural variation [4].

Recent studies further demonstrate how induced mutagenesis can address emerging climate-related challenges in pea production. Gamma-irradiated populations developed in Greece produced mutant families that maintained high yield while exhibiting reduced severity of Didymella pinodes infection [31,32]. This is particularly relevant as climate projections suggest that rising temperatures and fluctuating humidity levels are likely to increase fungal pathogen pressure in legumes [75]. Disease-tolerant mutants therefore contribute to stabilizing yield and reducing reliance on fungicides under increasingly unpredictable environmental conditions. In addition to stress tolerance, selected mutant pea lines also showed enhanced nutritional quality, including increased protein content and elevated Fe and Zn concentrations. This biofortification aspect is particularly important because elevated atmospheric CO₂ levels have been shown to reduce mineral nutrient concentrations in many crops [76]. By combining disease tolerance with improved nutritional value, mutant pea lines contribute simultaneously to agronomic resilience and human nutrition security. Their ability to balance growth and defense processes further supports adaptation to unstable agro-ecosystems and multiple environmental stresses [77,78].

Common bean provides another clear example of how mutation breeding can improve crop adaptation through modifications in plant architecture, productivity, and stress tolerance. Early mutation breeding work demonstrated the importance of radiation-induced architectural traits for improving agronomic performance. In North America, irradiation of the variety ‘Michelite’ produced early bush-type mutants, including the white-seed coat mutant ‘NEP-2’, which were widely used as parental material in breeding programs. These mutants and their derivatives became foundational components in the pedigrees of many white-seeded bean varieties and even today approximately 40% of the areas of white beans grown in North America originate from these varieties [79]. The bush growth habit enabled earlier maturity, improved stand uniformity, and greater suitability for mechanized harvesting, demonstrating the long-term breeding value of mutation-induced architectural traits.

Recent mutation breeding efforts in SEE further illustrate how induced mutagenesis can address current climate-related production challenges. Programs in North Macedonia and Bosnia and Herzegovina generated mutant lines with increased seed number per pod, improved plant architecture, and enhanced tolerance to drought and disease [25,36]. These traits are particularly valuable in smallholder-dominated farming systems typical of mountainous and marginal areas in SEE, where yield stability is often more critical than maximum yield potential. Mutants with improved reproductive efficiency can partially compensate for stress-induced flower or pod abortion during drought episodes, thereby maintaining productivity under variable environmental conditions.

5.4. Improvement of Industrial Crops: Implications for Food Security and Sustainability

Sunflower mutation breeding provides well-documented examples of how induced genetic variation can improve crop architecture and oil quality, thereby supporting adaptation to changing climatic conditions. One of the most influential achievements in sunflower mutation breeding was the development of the high-oleic mutant variety ‘Pervenets’, obtained through chemical mutagenesis using dimethyl-sulphate (DMS) in Krasnodar, Russia [80,81]. Following its introduction into breeding programs in the United States and Europe after 1980, the ‘Pervenets’ germplasm became the primary genetic source for the development of high-oleic sunflower hybrids [82].

Recent mutation breeding research in Serbia further illustrates how induced variation can support climate adaptation in oilseed crops. Early-flowering mutants derived from fast-neutron treatments flowered several days earlier than their parental lines without compromising yield [44]. In regions where late-summer drought and heat waves reduce seed set and oil accumulation, earlier flowering allows partial escape from terminal stress. Short-stature mutants also demonstrated improved standability and, in some cases, increased seed yield [44], thereby reducing lodging losses during extreme weather events. Additionally, mutants with increased oil content, reaching nearly 50%, provided enhanced oil yield stability [59]. Considering that oilseed crops are economically strategic in SEE, maintaining stable oil productivity under increasing heat and drought stress is critical for regional agricultural sustainability [14].

Cotton mutation breeding provides notable examples of how induced genetic variation can support both agronomic performance and economic stability in major fiber crops. One of the most prominent examples is the gamma-ray-induced mutant variety ‘NIAB-78’, released in Pakistan in 1983. This variety combined high yield with several adaptive traits, including shorter plant stature, determinate growth habit, heat tolerance, and early maturity. Its early maturation allowed it to escape severe bollworm infestation and made it particularly suitable for cotton–wheat rotation systems. Within five years of release, ‘NIAB-78’ covered more than 70% of the cotton-growing area in Punjab and played a major role in stabilizing cotton production and sustaining Pakistan’s textile industry [4]. Subsequent mutation breeding efforts continued to build on these achievements. The mutant-derived variety ‘NIAB Karishma’, released in 1996, improved heat tolerance, and high yield potential. Its cultivation expanded to nearly half a million hectares and generated substantial economic benefits for farmers. Similarly, in China the gamma-induced variety ‘Lumian No. 1’, released in 1974, became one of the most widely grown cotton varieties, exceeding one million hectares of cultivation annually until the late 1980s [83].

More recent mutation breeding work in CA further highlights the relevance of induced variation for climate adaptation. In Uzbekistan, cotton mutants developed under low-to-moderate gamma irradiation doses exhibited stable or increased boll numbers together with favorable fiber characteristics [43]. Because cotton production in CA largely occurs under arid and semi-arid conditions, identifying mutants that maintain productivity under water-limited environments is increasingly important. Such genotypes are better suited to withstand rising temperatures and increased evaporation rates associated with climate change. Incorporating these mutants into breeding programs targeting drought tolerance and fiber-quality diversification can therefore strengthen the resilience of cotton production systems in arid regions.

These results confirm that mutation breeding continues to provide valuable genetic resources for improving yield stability, grain quality, and stress resilience. Newly developed wheat mutants from SEE and CA therefore represent promising candidates for cultivation in stress-prone environments and valuable donors for broadening adaptive breeding pools.

Despite the successes detailed above, several limitations in crop mutation breeding in the SEE and CA regions remain to be overcome. Primary challenge is genotype dependency; the optimal dose for one variety often causes excessive lethality in another, requiring costly preliminary radiosensitivity assays. Furthermore, while mutation breeding is excellent for broadening crop genetic base, it is inherently random compared to the precision of CRISPR/Cas9 gene editing. However, in many SEE and CA nations, the regulatory landscape and public perception of gene editing remain complex, making mutation breeding a more accessible “non-GMO” path to trait improvement. Furthermore, infrastructure gaps in some countries also hinder further progress. Many mutation breeding programs lack high-throughput molecular confirmation tools and platforms (e.g., TILLING) to identify specific nucleotide changes early, relying instead on multi-year field phenotyping. Strengthening regional cooperation through shared irradiation facilities and centralized genomic platforms is essential to move from random discovery to targeted crop design.

6. Conclusions

In conclusion, this review demonstrates that mutation breeding in SEE and CA can be an effective, regionally adapted but robust pillar for climate-smart agriculture. Significant progress has been achieved in key trait–crop combinations, including drought and heat tolerance in cereals, improved oil quality and stress resilience in sunflower, enhanced seed retention and drought adaptation in sesame, and increased disease resistance in legumes. Our analysis shows that moderate-dose gamma irradiation (200–300 Gy) is the most effective regional strategy for balancing induced variability with plant survival in most of the crops. However, many mutant populations remain in early breeding generations, while multi-location evaluation, long-term assessment of trait stability, and molecular validation of candidate mutations are still limited. Breeding capacity also varies considerably among countries because of differences in infrastructure, available technologies, and financial resources. Consequently, relatively few mutant lines have progressed to officially released cultivars despite the large amount of promising breeding material. Future progress will depend on integrating mutation breeding with genomic selection, TILLING platforms, genome-wide association studies, next-generation sequencing, and AI-assisted digital breeding to accelerate the identification and utilization of beneficial mutations. Equally important will be expanding field-based physiological phenotyping under realistic stress environments and developing mutant populations targeting complex traits, including combined drought and heat tolerance, resource-use efficiency, and durable resistance to emerging pests and diseases.