Mapping of genomic regions associated with agronomic traits and resistance to diseases in Canadian spring wheat

• Author / Creator

  Perez Lara, Enid

• Wheat breeders, in addition to phenotypic selection, employ molecular markers in their programs for different purposes, including parental selection, quality control, analysis of advanced lines (cultivars), on genetic purity and identity, and for markers assisted selection. In the first study of this thesis we evaluated 158 recombinant inbred lines (RILs) population for flowering, maturity, plant height and grain yield under field conditions. With a subset of 1809 single nucleotide polymorphisms (SNPs) and 2 functional markers (Ppd-D1 and Rht-D1) we identified a total of 19 quantitative trait loci (QTLs) associated with flowering time under greenhouse (5) and field (6) conditions, maturity (5), grain yield (2) and plant height (1). These QTLs explained between 6.3 and 37.8% of the phenotypic variation. Only the QTLs on both 2D chromosome (adjacent to Ppd-D1) and 4D chromosome (adjacent Rht-D1) had major effects and, respectively reduced flowering and maturity time up to 5 days with a yield penalty of 436 kg ha-1 and reduced plant height by 13 cm, but increased maturity by 33 degree days. In the second study, we used genome-wide association analysis (GWAS) to identify markers associated with the wheat diseases leaf rust, stripe rust, tan spot, common bunt and three host selective toxins (HST) from Pyrenophora tritici-repentis (Ptr ToxA, B and C). We were able to identify 94 markers associated with all traits except Ptr ToxC sensitivity. Two major effect genomic regions on 5B and 1A were associated with Ptr ToxA sensitivity, of which the former coincided with the Tsn1 gene. For Ptr ToxB, two other major effect regions on chromosomes 2B and 5B. The genomic regions associated with common bunt mapped on chromosomes 2B, 4B and 7A, while those associated with leaf rust mapped at two positions on 2B. A single marker-trait was associated each to tan spot on 7B and for yellow rust on 2A. Finally, we investigated the phenotypic effect of 50 markers associated with 16 genes for resistance to rust and tan spot, and Ptr toxin reaction in a subset of 70 cultivars. We first report the marker makeup of the 70 cultivars to aid spring wheat breeders in parental choice for future crossing programs. We also identified 6-8 markers for yellow rust, 4-6 markers for leaf rust, 5-9 markers for tan spot resistance and 6-11 markers for Ptr ToxA insensitivity as the best predictors of the phenotypic variation observed across the 70 cultivars.

• Subjects / Keywords

  • Wheat
  • Mapping
  • Canadian spring wheat
  • Traits
  • Diseases
  • Resistance

• Graduation date

  Spring 2017

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3FJ29R36

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.