Dwarf bunt-resistant bread wheat accessions and SNP markers associated with DB resistance identified in this study are valuable resources for characterization and deployment of DB resistance in bread wheat. Dwarf bunt (DB), caused by Tilletia controversa J.G. Kühn, can significantly reduce grain yield and quality on autumn-sown wheat in regions with prolonged snow cover. DB can be managed with the use of resistant cultivars. The objectives of the present study were to characterize DB resistance in a large set of bread wheat accessions from the National Small Grains Collection and use a genome-wide association study approach to identify genetic loci associated with DB resistance. A total of 292 accessions were selected using historical DB resistance data recorded across many trials and years in the Germplasm Resources Information Network (GRIN) and re-tested for DB resistance in replicated field nurseries in Logan, UT, in 2017, 2018, and 2019. Ninety-eight accessions were resistant with DB normalized incidence ≤ 10%, and twenty-eight of these were highly resistant with DB normalized incidence ≤ 1% in both GRIN and the field nurseries. Based on the presence of marker haplotypes of the four published dwarf bunt QTL on 6DS, 6DL, 7AL, and 7DS, highly resistant accessions identified in this study may provide novel resistance and should be further evaluated. This study validated one previously identified QTL on 6DS and identified an additional locus on 6DS. These loci explained 9-15% of the observed phenotypic variation. The resistant accessions and molecular markers identified in the present study may provide valuable resources for characterization and deployment of DB resistance in bread wheat.

中文翻译：

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来自美国农业部国家小谷物收藏的面包小麦种质中矮化短打抗性的遗传特征和全基因组关联作图。

本研究中鉴定出的抗矮化面包小麦种质和与 DB 抗性相关的 SNP 标记是表征和部署面包小麦 DB 抗性的宝贵资源。由 Tilletia controversa JG Kühn 引起的矮矮胖子 (DB) 会显着降低积雪时间延长地区秋播小麦的产量和品质。DB可以使用抗性品种进行管理。本研究的目的是表征来自国家小谷物收藏的大量面包小麦种质中的 DB 抗性，并使用全基因组关联研究方法来识别与 DB 抗性相关的遗传基因座。使用种质资源信息网络 (GRIN) 中记录的许多试验和年份的历史 DB 抗性数据共选择了 292 个种质，并于 2017 年、2018 年和 2019 年在犹他州洛根的复制田间苗圃中重新测试了 DB 抗性. 98 个种质具有耐药性，DB 标准化发生率≤10%，其中 28 个具有高度耐药性，在 GRIN 和田间苗圃中，DB 标准化发生率≤1%。基于在 6DS、6DL、7AL 和 7DS 上存在的四种已发表的矮胖子 QTL 的标记单倍型，本研究中鉴定的高抗性种质可能提供新的抗性，应进一步评估。该研究验证了一个先前在 6DS 上鉴定的 QTL，并在 6DS 上鉴定了一个额外的基因座。这些基因座解释了观察到的表型变异的 9-15%。