The Science of Breeding Resilient Crops for a Changing Climate
In the vast steppes of Ukraine, often called the "breadbasket of Europe," a quiet revolution is taking place in agricultural research laboratories and experimental fields. As climate change intensifies, bringing unpredictable precipitation patterns and extended drought periods, scientists are racing against time to develop winter wheat varieties that can withstand increasingly harsh conditions while maintaining high yields and quality. The stakes are enormously high—wheat represents not just an economic commodity but a foundation of global food security.
Recent reports from the Joint Research Centre highlight that despite favorable conditions in some regions, persistent dryness in eastern Ukraine continues to negatively affect winter cereals, underscoring the urgency of drought resistance research . This article, the third in a series exploring years with different moisture supply, delves into the fascinating science behind breeding drought-resistant winter wheat varieties specifically adapted to the challenging environment of the Ukrainian steppe. We'll explore how scientists are unlocking the secrets of plant stress tolerance, examine groundbreaking experiments that reveal the inner workings of wheat under duress, and discover how these advances translate into more resilient crops for farmers.
Developing wheat varieties that thrive with limited water resources
Maintaining grain quality and baking properties under stress conditions
Breeding crops resilient to increasingly variable climate patterns
To understand the remarkable achievements of wheat breeders, we must first appreciate what happens to wheat plants when water becomes scarce. Drought stress triggers a complex cascade of responses at molecular, biochemical, and physiological levels that can either make or break a harvest.
When wheat experiences water shortage, the first line of defense is the closure of microscopic pores on leaf surfaces called stomata. This conservation strategy prevents water loss but comes at a cost—with stomata closed, carbon dioxide intake drops, leading to a decline in photosynthesis. As a result, the plant produces less energy while simultaneously experiencing an accumulation of reactive oxygen species (ROS) that damage cellular structures, including the precious photosynthetic apparatus 3 .
To counter this oxidative damage, wheat plants activate their antioxidant defense systems, producing enzymes like superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) that scavenge harmful ROS 2 3 . Simultaneously, plants accumulate compatible solutes—compounds like proline and various soluble sugars that help maintain cellular water balance through osmosis and protect proteins and membranes from damage 4 .
Stomatal closure, ABA hormone accumulation, photosynthesis reduction
Activation of antioxidant systems, osmotic adjustment, compatible solute accumulation
Root system modification, altered growth patterns, resource reallocation
At the hormonal level, abscisic acid (ABA) emerges as a key player in drought response. ABA levels rise rapidly during water stress, triggering stomatal closure and activating stress-protective genes 2 5 . Other hormones, including jasmonic acid, salicylic acid, and gibberellins, also participate in fine-tuning the plant's response to drought 2 .
Ukrainian plant breeders have made significant strides in developing winter wheat varieties specifically adapted to the drought-prone steppe environment. Through decades of selective breeding and advanced techniques like interspecific hybridization and gene introgression, they have created a portfolio of resilient cultivars that form the backbone of sustainable wheat production in challenging regions 1 .
The Plant Breeding and Genetics Institute – National Center of Seed and Cultivar Investigation (PBGI – NCSCI) has been at the forefront of these efforts, leading through multiple cultivar replacements over the past 65 years 1 . The most recent introductions (representing the sixth cultivar replacement) include varieties such as 'Lainer', 'Shliachetnyi', 'Blyskuchyi', 'Almaznyi', 'Yantarnyi', and 'Kryshtalevyi', classified as leucurum types; 'Areal Odeskyi' and 'Hranatovyi' as hordeiforme types; and 'Prestyzhnyi' and 'Yaskravyi' as leucomelan types 1 .
These modern cultivars are characterized as intensive types with universal use and boast high resistance to lodging, improved drought tolerance, and resistance to common diseases. Critically, they maintain excellent grain quality with high vitreousness and protein content despite water limitations 1 . Among bread wheat varieties, 'Odeska 267' has emerged as a particularly drought-tolerant cultivar recommended specifically for the Steppe and Forest-Steppe zones of Ukraine, while 'Darunok Podillia' serves as a drought-sensitive comparator in research studies 3 .
High drought and heat resistance with 13.0-13.9% protein content and 28-30% wet gluten 3 . Recommended for Steppe and Forest-Steppe zones.
Used as a comparator in research studies to understand drought sensitivity mechanisms and responses.
To understand how researchers evaluate drought resistance in winter wheat, let's examine a comprehensive study that investigated the response of different varieties to water stress during the critical flowering stage. This experiment provides a perfect case study of the scientific methods used to identify drought-tolerant traits.
The research was conducted using potted plants of two contrasting cultivars: drought-tolerant 'Odeska 267' and drought-sensitive 'Darunok Podillia' 3 . The plants were grown in luvisol soil mixed with sand (4:1 ratio) under natural conditions with protective canopies to exclude unpredictable rainfall. Key growth stages were monitored using the standardized BBCH scale, which allows precise comparison of developmental phases across different plants and conditions 3 .
The drought treatment was initiated at a critical moment—the beginning of flowering (BBCH 61), when water stress can dramatically impact grain development and yield. Watering was withheld until soil moisture decreased to 30% of field capacity, and this stress level was maintained for seven days before resuming normal irrigation 3 . This approach allowed researchers to simulate a transient drought event similar to what might occur naturally during the sensitive flowering period.
Contrasting Cultivars
Days of Drought Stress
Field Capacity Threshold
This comprehensive approach allowed scientists to connect molecular responses to ultimately important agronomic and quality traits.
The experimental results revealed fascinating differences between the drought-tolerant and drought-sensitive varieties, providing insights into the mechanisms that confer resilience to water stress.
When faced with water limitation, the drought-tolerant 'Odeska 267' demonstrated superior water management and maintained more stable photosynthesis compared to the sensitive 'Darunok Podillia' 3 . The tolerant cultivar effectively used photorespiration to dissipate excessive light energy, reducing the damage to its photosynthetic apparatus. Furthermore, 'Odeska 267' showed earlier induction of the antioxidant enzyme superoxide dismutase, resulting in less oxidative damage and better preservation of cellular functions 3 .
These physiological advantages translated into tangible benefits for grain yield and quality. While both varieties experienced some yield reduction under drought conditions, the tolerant cultivar maintained better grain filling and, crucially, preserved a more stable gluten profile that defines bread-making quality 3 . This maintenance of quality under stress is particularly important for farmers' economic returns, as wheat with poor baking quality commands lower prices despite acceptable yields.
Perhaps most intriguing were the differences observed at the protein level. The grain proteome analysis revealed that water deficit during flowering triggered distinct changes in protein composition between the two cultivars. The drought-sensitive 'Darunok Podillia' showed accumulation of certain gluten components, while the tolerant 'Odeska 267' accumulated more metabolic proteins 3 .
These findings have implications beyond agricultural productivity—they touch on human health concerns related to wheat consumption. Some wheat proteins can trigger intolerances or allergic responses in sensitive individuals, and the observation that drought stress alters the protein spectrum highlights the complex connections between growing conditions, wheat composition, and potential health impacts 3 .
| Parameter | Drought-Tolerant 'Odeska 267' | Drought-Sensitive 'Darunok Podillia' |
|---|---|---|
| Water Management | Effective | Ineffective |
| Photosynthesis Decline | Moderate | Severe |
| Photorespiration Use | Effective dissipation of excess light energy | Less efficient |
| Antioxidant Induction | Rapid superoxide dismutase activation | Delayed or insufficient response |
| Oxidative Damage | Limited | Significant |
| Grain Protein Stability | Maintained gluten profile | Altered gluten composition |
| Yield Impact | Reduced but more stable | More severely reduced |
Table 1: Comparison of physiological responses to drought stress between tolerant and sensitive wheat varieties 3
| Quality Parameter | Drought-Tolerant 'Odeska 267' | Drought-Sensitive 'Darunok Podillia' |
|---|---|---|
| Gluten Quality | Stable profile | Significant alterations |
| Protein Composition | Increased metabolic proteins | Increased gluten components |
| Baking Quality | Better maintained | More compromised |
| Medical Relevance | Potentially fewer problematic protein changes | Accumulation of potentially problematic gluten components |
Table 2: Impact of drought stress on grain quality parameters in contrasting wheat varieties 3
Studying drought resistance in wheat requires specialized methodologies and reagents that allow researchers to precisely measure plant responses at multiple levels. The following toolkit represents essential approaches used in cutting-edge drought resistance research.
| Research Tool | Function/Application | Example from Studies |
|---|---|---|
| Controlled Drought Stress | Simulate specific drought conditions at critical growth stages | Water withholding at flowering stage to 30% field capacity 3 |
| Antioxidant Enzyme Assays | Quantify oxidative stress response | Superoxide dismutase, peroxidase, catalase activity measurements 2 3 |
| Phytohormone Profiling | Analyze hormonal changes during stress and recovery | ABA, JA, GA, SA quantification via HPLC 2 |
| Transcriptome Analysis | Identify gene expression changes under drought | RNA sequencing to find differentially expressed genes 2 |
| Proteomic Analysis | Characterize changes in protein composition | Grain proteome profiling to identify quality alterations 3 |
| Physiological Trait Measurement | Assess functional responses to stress | Photosynthesis parameters, water use efficiency 3 4 |
| Soil Moisture Monitoring | Precisely control and document water availability | TDR soil moisture meters at different soil depths 2 |
Table 3: Research methodologies employed in drought resistance studies of winter wheat 2 3 4
Genomic, transcriptomic, and proteomic analyses to understand genetic basis of drought tolerance
Enzyme activity measurements, hormone profiling, and metabolite analysis
Photosynthesis parameters, water relations, growth analysis, and yield components
The research on drought resistance in winter wheat reveals a complex picture of plant stress response that spans from molecular levels to whole-plant physiology. The differences between drought-tolerant and drought-sensitive varieties—from their antioxidant systems and hormonal regulation to their protein composition and ultimate grain quality—provide valuable insights for future breeding efforts.
As climate variability increases, the work of wheat breeders becomes ever more crucial. The latest cultivars emerging from Ukrainian research institutions represent remarkable achievements in combining drought tolerance with high quality, but the challenge continues. Future breeding will likely incorporate molecular markers for drought resilience traits, allowing more precise selection of desirable genotypes. Genes encoding proteins like thaumatin-like protein, 14-3-3 protein, peroxiredoxins, and specific transcription factors have been identified as potential markers for drought tolerance 3 .
Moreover, understanding the rehydration compensation effect—whereby plants not only recover from drought but show compensatory growth after rewatering—opens new avenues for improving yield stability 2 . The ability to rapidly recover after stress relief may be as important as drought tolerance itself in many agricultural scenarios.
As we look to the future, the integration of traditional breeding with modern genomic tools and precise physiological understanding promises to deliver wheat varieties that can thrive despite the challenges posed by a changing climate. This research represents not just scientific advancement but a vital contribution to food security in Ukraine and beyond, ensuring that the steppe continues to fulfill its role as a productive breadbasket for generations to come.
| Cultivar Name | Type | Key Drought Adaptation Features | Quality Characteristics |
|---|---|---|---|
| Odeska 267 | Bread wheat | High drought and heat resistance | 13.0-13.9% protein, 28-30% wet gluten 3 |
| Lainer | Durum wheat (leucurum) | High drought resistance, lodging resistance | High vitreousness, high protein content 1 |
| Areal Odeskyi | Durum wheat (hordeiforme) | Drought tolerance, intensive type | High grain quality, suitable for steppe zones 1 |
| Prestyzhnyi | Durum wheat (leucomelan) | Drought resistance, disease resistance | Above average protein content 1 |
Table 4: Promising winter wheat cultivars developed for drought-prone regions of Ukraine 1 3