Climate change poses a significant threat to wheat production. Developing resilient wheat varieties with enhanced genetic variability is crucial to mitigating the constraints posed by changing climatic conditions. Our study focuses on identifying climate-resilient wheat cultivars from an International Spring Wheat Collection (ISWC) composed of 150 cultivars from diverse regions across North and South America, including East and West Canada, Argentina, Brazil, Chile, Mexico, Paraguay, the United States, and Uruguay. We evaluate the ISWC genomically and phenotypically at six distinct locations: East Canada (three locations), Brazil, Paraguay, and Uruguay.

The ISWC undergoes a comprehensive evaluation for both above and below-ground traits, such as crop ground cover, normalized difference vegetation index (NDVI), root system architecture, yield and its components, disease resistance, and baking quality. This provides crucial insights into genetic variability and adaptability. Biotic and abiotic factors were evaluated in separate trials (2022-2024), with fungicides used in abiotic experiments. Extreme climate variations occurred during the study years across locations.

Our phenotyping assessments have revealed significant genotype variation among wheat cultivars, with some demonstrating superior adaptability across various locations. Notable variability was observed in all analyzed traits. In 2022, the Paraguay trial, harshly affected by drought and frost, had the lowest grain yield mean of 1.4 ton/ha (55 kg/ha to 2.6 ton/ha), while the highest mean was in Brazil at 6.3 ton/ha (1.8 to 9.2 ton/ha). Similarly, kernel weights (19.8 to 51.9 g/thousand kernels) and test weights (51.9 to 84.9 kg/hectolitre) exhibited considerable ranges, highlighting genetic diversity. Disease reaction was assessed based on natural infection and artificial inoculation in disease nurseries (leaf rust, stripe rust, and Fusarium head blight).

The ISWC is being genotyped using markers associated with specific traits of interest, such as disease and pest resistance, phenology, and end-use quality. Genotyping-by-sequencing (GBS) has revealed significant genetic diversity, delineating eight sub-populations aligned with specific breeding programs or regions, informative of natural selections, and breeding efforts. Our ongoing GWAS analysis on multi-environmental data aims to pinpoint genetic loci associated with climate-resilient traits, emphasizing validation and reproducibility to ensure robust findings.

By integrating three years of data (2022 to 2024) with genotyping insights, we strive to comprehensively understand genotype-phenotype-environment relationships. This holistic approach empowers breeders to develop wheat varieties resilient to climate change, bolstering global food security amidst evolving environmental challenges.

Keywords: wheat, climate-smart, adaptation, genotypic diversity, America