Ronja.wonneberger@slu.se, therese.bengtsson@slu.se

The CResWheat project is a collaborative pre-breeding initiative involving researchers and spring wheat breeders from the Nordic and Baltic countries. Its primary goal is to enhance climate resilience of Nordic spring wheat by improving yield, yield stability, and resistance to pests and diseases as well as abiotic stresses.

The cultivation of spring wheat (Triticum aestivum L.) plays a vital role in the climatic conditions of northern Europe, especially in regions where winter wheat cultivation encounters challenges. Historically, this region has relied on its temperate climate for successful wheat production. However, climate change is increasingly altering the dynamics of precipitation, leading to erratic rainfall patterns and prolonged dry spells during critical growth stages of wheat.

To identify sources of drought stress resistance in Nordic spring wheat, twelve selected Nordic spring wheat lines were grown under controlled conditions at the LemnaTec high-throughput phenotyping facility at IPK Gatersleben, Germany. Three week-old plants were subjected to either regular watering (up to 90% plant available water (PAW)) or reduced watering (up to 10% PAW) to induce a moderate early-season drought stress for 22 days, followed by a five-day regeneration phase.

During this time, imaging-based phenotyping of the plants and soil water measurements were performed daily, photosynthetic measurements were taken at four time points and leaf samples for metabolomics analysis were taken at four time points during and after the drought treatment. After harvest, grain and spike traits and tiller number gain were recorded for each plant.

Biomass, tiller number gain, plant weight, thousand grain weight and traits associated with grain size and shape were most strongly affected by drought. Biomass was reduced between 66 and 79% in the different genotypes. Differential metabolomics responses to drought became apparent at ca. 13 days after the start of the drought treatment.

We identified several differentially accumulated metabolites between control and drought-treated plants that may be used as biomarkers in breeding for drought stress tolerance. In total, 94 metabolites were significantly accumulated and 102 metabolites were significantly reduced under drought stress in at least one of the four time points.

In addition, we were able to identify metabolites that are strongly correlated with different phenotypes and should therefore be an interesting starting point for further studies on how metabolic changes affect phenotypes and yield components and on their predictive ability for plant performance.