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The Plant Genome Abstract - Original Research

Evaluation of Genetic Diversity and Host Resistance to Stem Rust in USDA NSGC Durum Wheat Accessions


This article in TPG

  1. Vol. 10 No. 2
    unlockOPEN ACCESS
    Received: July 22, 2016
    Accepted: Feb 14, 2017
    Published: June 8, 2017

    * Corresponding author(s): shiaoman.chao@ars.usda.gov
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  1. Shiaoman Chao *a,
  2. Matthew N. Rouseb,
  3. Maricelis Acevedocd,
  4. Agnes Szabo-Hevere,
  5. Harold Bockelmanf,
  6. J. Michael Bonmanf,
  7. Elias Eliase,
  8. Daryl Klindwortha and
  9. Steven Xua
  1. a USDA–ARS, Cereal Crops Research Unit, 1605 Albrecht Blvd N, Fargo, ND 58102
    b USDA–ARS, Cereal Disease Lab., Dep. of Plant Pathology, Univ. of Minnesota, St. Paul, MN 55018
    c Dep. of Plant Pathology, North Dakota State Univ., Fargo, ND 58108
    d current address: Delivering Genetic Gain in Wheat Project, International Programs, Cornell Univ., Ithaca, NY 14583
    e Dep. of Plant Sciences, North Dakota State Univ., Fargo, ND 58108
    f USDA–ARS, Small Grains and Potato Germplasm Research Unit, Aberdeen, ID 83210
Core Ideas:
  • Characterized the utility of a core subset of USDA–NSGC worldwide durum wheat accessions
  • The durum core subset captured a considerable amount of genetic diversity
  • Identified accessions’ resistance to wheat stem rust pathogen races
  • Assessed genome-wide LD present in the durum core subset


The USDA–ARS National Small Grains Collection (NSGC) maintains germplasm representing global diversity of small grains and their wild relatives. To evaluate the utility of the NSGC durum wheat (Triticum turgidum L. ssp. durum) accessions, we assessed genetic diversity and linkage disequilibrium (LD) patterns in a durum core subset containing 429 lines with spring growth habit originating from 64 countries worldwide. Genetic diversity estimated using wheat single-nucleotide polymorphism (SNP) markers showed considerable diversity captured in this collection. 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 evaluated accessions for resistance to wheat stem rust, caused by a fungal pathogen, Puccinia graminis Pers. Pers. f. sp. tritici Eriks. and E. Henn (Pgt), using races from both eastern Africa and North America, at 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 a result of strong G × 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.

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