New herbicide resistance traits in wheat were produced through the use of induced mutagenesis. While herbicide-resistant crops have become common in many agricultural systems, wheat has seen few introductions of herbicide resistance traits. A population of Hatcher winter wheat treated with ethyl methanesulfonate was screened with quizalofop to identify herbicide-resistant plants. Initial testing identified plants that survived multiple quizalofop applications. A series of experiments were designed to characterize this trait. In greenhouse studies the mutants exhibited high levels of quizalofop resistance compared to non-mutant wheat. Sequencing ACC1 revealed a novel missense mutation causing an alanine to valine change at position 2004 (Alopecurus myosuroides reference sequence). Plants carrying single mutations in wheat's three genomes (A, B, D) were identified. Acetyl co-enzyme A carboxylase in resistant plants was 4- to 10-fold more tolerant to quizalofop. Populations of segregating backcross progenies were developed by crossing each of the three individual mutants with wild-type wheat. Experiments conducted with these populations confirmed largely normal segregation, with each mutant allele conferring an additive level of resistance. Further tests showed that the A genome mutation conferred the greatest resistance and the B genome mutation conferred the least resistance to quizalofop. The non-transgenic herbicide resistance trait identified will enhance weed control strategies in wheat.

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Characterization of population structure and genetic relatedness within wheat (Triticum aestivum L.) germplasm collections is critical for genomewide association studies (GWAS) and training population development for genomic selection (GS). Cooperative regional or international nurseries are well suited for GWAS and GS studies due to the availability of multi‐environment datasets that are often produced. In this study, we analyzed population structure and genetic diversity of 283 genotypes from 7 yr of the Winter Wheat Eastern European Regional Yield Trial (WWEERYT). The collection was genotyped with single‐nucleotide polymorphism (SNP) markers obtained via genotyping‐by‐sequencing; a subset of 548 highly polymorphic SNPs was used for all analyses. Population structure was composed of seven subpopulations when using a correlated allele frequencies model in the program STRUCTURE. The genotype's breeding program of origin was closely related to, but not a perfect indicator of, subpopulation assignment. Genotypes of Central and Eastern European origin were assigned to six of the seven subpopulations, while genotypes from the United States were assigned to only two of the seven subpopulations. The lowest value for Wright's fixation index observed (FST = 0.20) was between a population of predominately Turkey‐CIMMYT‐ICARDA genotypes and genotypes from the United States, indicating a close relationship between genotypes from these two regions. The characterization of population structure and genetic diversity within the WWEERYT nurseries will allow breeders to accurately select and test germplasm that is genetically diverse from their own by targeting germplasm from different subpopulations identified under model 1. The results presented in this paper will help to foster the utilization and exchange of WWEERYT germplasm across diverse global winter wheat production regions.