WHEATSUSTAIN

The WHEATSUSTAIN project aims to elucidate the complex regulatory networks underlying efficient resource use and adaptive responses to water and nutrient limitations in wheat, integrating physiological, genomic, and metabolomic approaches. Specifically, the project investigates the biological mechanisms governing adaptation to water stress and nitrogen (N) and phosphorus (P) availability, both individually and in combination.

Developmental, physiological, transcriptomic, and metabolomic changes are analyzed across different growth stages and tissues under near-field conditions. Updated reference genomes and gene and metabolic network analyses are also employed to interpret stress responses, taking into account natural variation through the tetraploid wheat pangenome.

Expected Results

The project aims to identify key mechanisms regulating wheat adaptation to water and nutrient stress, contributing to the development of strategies to improve resource use efficiency. The results will provide a scientific foundation for breeding more resilient and productive varieties under multiple stress conditions.

Results Obtained

The WheatSustain project investigated how durum and bread wheat respond to environmental stress conditions associated with reduced water and essential nutrients, particularly nitrogen (N) and phosphorus (P). Two well-characterized reference cultivars were selected: Svevo for durum wheat and Chinese Spring for bread wheat.

To assess plant responses under controlled yet realistic conditions, plants were grown in lysimeters—systems that mimic field-like dynamics while allowing precise regulation of water and nutrient supply. Both optimal and limiting conditions for water and nutrient availability were applied, simulating more sustainable cropping scenarios.

Seven treatments (T1–T7) were implemented, combining different levels of water, nitrogen (N), and phosphorus (P), including optimal conditions (W+N+P) and realistic limitations of individual resources.

Key physiological parameters—stomatal conductance, chlorophyll content (SPAD), and fluorescence—were measured, and leaf and reproductive tissues were collected for analyses of yield components, grain quality (protein content, gluten, Zeleny index, alveograph W), and metabolite profiles (sugars, free amino acids, phenolics, flavonoids, and N, P, and C contents).

The WheatSustain project clearly demonstrated that the combined availability of water, nitrogen, and phosphorus is the primary determinant of wheat yield, quality, and metabolic responses.

Key Results

· Maximum performance under balanced conditions: The highest performance was achieved under balanced nutrient regimes (T4: water + N + P; T6: N + P), which optimized photosynthesis, biomass accumulation, and grain quality (proteins and gluten). These findings confirm the central role of nitrogen and its strong synergistic interaction with phosphorus.

· Total stress (T3) as a physiological limit: The combined absence of water and nutrients resulted in the lowest values for all parameters (growth, photosynthesis, quality), defining a critical threshold for productivity.

· Ineffectiveness of single inputs (T2, T7): Unbalanced inputs (water only or phosphorus only) led to poor performance, highlighting that no single factor alone is sufficient to sustain growth and quality.

Genotypic Differences

Clear strategic differences between cultivars were observed:

· Chinese Spring (bread wheat) exhibited a growth- and yield-oriented response, characterized by high biomass production and stable performance.

· Svevo (durum wheat) showed greater efficiency in grain quality traits (protein and gluten content) and activated defensive metabolic responses (phenolics and flavonoids) under stress conditions.

Svevo durum wheat displayed higher metabolic plasticity (amino acids and defense compounds), whereas Chinese Spring bread wheat maintained greater physiological stability.

Scientific and Practical Impact

· Identification of biomarkers and candidate genes associated with nitrogen use efficiency (NUE) and water use efficiency (WUE);

· Demonstration of the importance of studying combined stresses (rather than single stress factors) to better represent real field conditions;

· Provision of robust physiological and genomic knowledge to support:

1. Breeding of more resilient and sustainable wheat varieties;

2. Optimization of agronomic management of water and fertilizers.

Conclusion

Sustainable wheat productivity requires an integrated approach combining genetics, nutrition, and resource management. WheatSustain clearly identifies the key mechanisms upon which to build new crop ideotypes with high efficiency and environmental resilience.