Characterization and mapping of leaf rust resistance in four durum wheat cultivars

PLoS One. 2018 May 10;13(5):e0197317. doi: 10.1371/journal.pone.0197317. eCollection 2018.

Abstract

Widening the genetic basis of leaf rust resistance is a primary objective of the global durum wheat breeding effort at the International Wheat and Maize Improvement Center (CIMMYT). Breeding programs in North America are following suit, especially after the emergence of new races of Puccinia triticina such as BBG/BP and BBBQD in Mexico and the United States, respectively. This study was conducted to characterize and map previously undescribed genes for leaf rust resistance in durum wheat and to develop reliable molecular markers for marker-assisted breeding. Four recombinant inbred line (RIL) mapping populations derived from the resistance sources Amria, Byblos, Geromtel_3 and Tunsyr_2, which were crossed to the susceptible line ATRED #2, were evaluated for their reaction to the Mexican race BBG/BP of P. triticina. Genetic analyses of host reactions indicated that leaf rust resistance in these genotypes was based on major seedling resistance genes. Allelism tests among resistant parents supported that Amria and Byblos carried allelic or closely linked genes. The resistance in Geromtel_3 and Tunsyr_2 also appeared to be allelic. Bulked segregant analysis using the Infinium iSelect 90K single nucleotide polymorphism (SNP) array identified two genomic regions for leaf rust resistance; one on chromosome 6BS for Geromtel_3 and Tunsyr_2 and the other on chromosome 7BL for Amria and Byblos. Polymorphic SNPs identified within these regions were converted to kompetitive allele-specific PCR (KASP) assays and used to genotype the RIL populations. KASP markers usw215 and usw218 were the closest to the resistance genes in Geromtel_3 and Tunsyr_2, while usw260 was closely linked to the resistance genes in Amria and Byblos. DNA sequences associated with these SNP markers were anchored to the wild emmer wheat (WEW) reference sequence, which identified several candidate resistance genes. The molecular markers reported herein will be useful to effectively pyramid these resistance genes with other previously marked genes into adapted, elite durum wheat genotypes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromosome Mapping
  • Disease Resistance / genetics*
  • Genes, Plant
  • Genetic Linkage
  • Phenotype
  • Plant Breeding
  • Plant Diseases / genetics*
  • Polymorphism, Single Nucleotide
  • Species Specificity
  • Triticum / genetics*

Grants and funding

This research was conducted as part of the Canadian Triticum Applied Genomics (CTAG2) project. We are grateful for the financial support of Genome Canada, Genome Prairie, Western Grains Research Foundation, Saskatchewan Wheat Development Commission, Alberta Wheat Development Commission and the Saskatchewan Ministry of Agriculture. Scholarships were also provided by the Saskatchewan Innovation and Opportunity scholarship and the Rene Vandeveld postgraduate scholarship. CIMMYT’s contribution to the present work has been made possible thanks to funding from (1) “Patronato por la Investigación y Experimentación Agrícola del Estado de Sonora (PIEAES)” / Fundacíón Produce Sonora, México, and (2) the “Durable Rust Resistance Wheat (DRRW)” Project as part of the Borlaug Global Rust Initiative (BGRI). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.