Evaluation of wheat blast resistance in the USDA hard winter wheat (Triticum aestivum L.) Northern and Southern Regional Performance Nurseries.

Wheat blast, caused by the Triticum pathotype of Pyricularia oryzae, is an emerging disease that threatens the global supply of wheat. The pathogen was first reported in Brazil and subsequently spread to the neighboring countries of Argentina, Bolivia, and Paraguay. More recently, wheat blast was reported in Asia and Africa, having been observed in Bangladesh and Zambia. The transcontinental spread of the pathogen has heightened awareness of the disease and has underscored the need to prepare for potential introductions into major wheat production regions. To this end, we have conducted greenhouse evaluations of the 2017 - 2020 hard winter wheat (Triticum aestivum L.) entries of the USDA-coordinated Northern and Southern Regional Performance Nurseries (NRPN and SRPN, respectively) of the U.S. Great Plains using an aggressive isolate of the pathogen, B-71, collected in Bolivia in 2012. Based on molecular marker analysis, all potentially resistant entries in both the NRPN and SRPN were in possession of the distal chromosomal translocation of 2N^VS from Aegilops ventricosa, which has previously been associated with wheat blast resistance. No potentially new sources of resistance were evident in the 2017 - 2020 regional performance nurseries, which highlights the need for the continued use of 2N^VS donor lines in Great Plains wheat breeding programs.