Evaluation of wheat blast resistance in the USDA Uniform Eastern and Southern Soft Red Winter Wheat ( Triticum aestivum ) Nurseries

Wheat blast is an emerging disease caused by the highly virulent Triticum pathotype of the fungal pathogen Pyricularia oryzae that threatens wheat production worldwide. Relatively few sources of resistance to wheat blast have been identified, and no single source of resistance that protects against all strains of the pathogen has been found. We have conducted greenhouse evaluations of wheat entries submitted to the 2021 USDA-coordinated Uniform Eastern and Southern Soft Red Winter Wheat (Triticum aestivum L.) Nurseries for wheat blast resistance using an aggressive isolate (B-71) of the pathogen collected in Bolivia in 2012. From a total of 72 breeder entries, only three were highly resistant (<10% average disease severity) and six were moderately resistant (<20% average disease severity). All potentially resistant entries possessed the distal chromosomal translocation of 2N ^V S from Aegilops ventricosa, which was previously associated with wheat blast resistance. No potentially new sources of resistance were evident in either of the soft red winter wheat nurseries, underscoring the importance of using 2N ^V S donor lines in wheat breeding programs to protect against wheat blast.