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GrainGenes Reference Report: TPG-10-71

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Reference
TPG-10-71
Title
Evaluation of Genetic Diversity and Host Resistance to Stem Rust in Durum Wheat Accessions from the USDA National Small Grains Collection
Journal
The Plant Genome
Year
2017
Volume
10
Author
Chao SM
[ Show all 9 ]
Abstract
The USDA-ARS National Small Grains Collection (NSGC) located in Aberdeen, ID maintains collections representing the global diversity of small grains and their wild relatives. To evaluate the utility of the NSGC durum wheat accessions, we assessed genetic diversity and LD patterns in a durum core subset containing 429 lines with spring growth habit originating from 64 countries worldwide. Genetic diversity estimated using wheat SNP markers showed a considerable amount of diversity captured in this collection. Population structure was generally weak with an overall Fst value of 0.06. Average LD decayed over a genetic distance to within 3 cM at r2 = 0.2, with a fast LD decay for markers linked at > 5 cM. We then evaluated the accessions for resistance to wheat stem rust using five races including TTKSK (Ug99), TRTTF, JRCQC, and a bulk of six North American races at the seedling and adult plant stages. Five accessions were identified as resistant to all stem rust pathogen races evaluated. Genome-wide association analysis detected 17 significant associations at the seedling stage with nine likely corresponding to Sr7, Sr12, and Sr13, and the remaining potentially being novel genes located on six chromosomes. A higher frequency of resistant accessions was found at the adult plant stage than at the seedling stage. However, few significant associations were detected possibly due to strong G x E interactions not properly accounted for in the mixed model. Nonetheless, the resistant accessions identified in this study should provide wheat breeders with valuable resources for improving stem rust resistance.
Gene
Sr12 (Triticum)
Sr13 (Triticum)
Sr7 (Triticum)
Map Data
Durum Wheat, NSGC Sr
QTL
QSr.locus-3B
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Trait Study
Stem rust, NSGC 2012-2014