Table_2_Genetic mapping of leaf rust (Puccinia triticina Eriks) resistance genes in six Canadian spring wheat cultivars.xlsx

The Canada Western Red Spring wheat (Triticum aestivum L.) cultivars AAC Concord, AAC Prevail, CDC Hughes, Lillian, Glenlea, and elite line BW961 express a spectrum of resistance to leaf rust caused by Puccinia triticina Eriks. This study aimed to identify and map the leaf rust resistance of the cultivars using three doubled haploid populations, AAC Prevail/BW961 (PB), CDC Hughes/AAC Concord (HC), and Lillian/Glenlea (LG). The populations were evaluated for seedling resistance in the greenhouse and adult plant disease response in the field at Morden, MB for 3 years and genotyped with the 90K wheat Infinium iSelect SNP array. Genetic maps were constructed to perform QTL analysis on the seedling and field leaf rust data. A total of three field leaf rust resistance QTL segregated in the PB population, five in the HC, and six in the LG population. In the PB population, BW961 contributed two QTL on chromosomes 2DS and 7DS, and AAC Prevail contributed a QTL on 4AL consistent across trials. Of the five QTL in HC, AAC Concord contributed two QTL on 4AL and 7AL consistent across trials and a QTL on 3DL.1 that provided seedling resistance only. CDC Hughes contributed two QTL on 1DS and 3DL.2. Lillian contributed four QTL significant in at least two of the three trials on 2BS, 4AL, 5AL, and 7AL, and Glenlea two QTL on 4BL and 7BL. The 1DS QTL from CDC Hughes, the 2DS from BW961, the 4AL from the AAC Prevail, AAC Concord, and Lillian, and the 7AL from AAC Concord and Lillian conferred seedling leaf rust resistance. The QTL on 4AL corresponded with Lr30 and was the same across cultivars AAC Prevail, AAC Concord, and Lillian, whereas the 7AL corresponding with LrCen was coincident between AAC Concord and Lillian. The 7DS and 2DS QTL in BW961 corresponded with Lr34 and Lr2a, respectively, and the 1DS QTL in CDC Hughes with Lr21. The QTL identified on 5AL could represent a novel gene. The results of this study will widen our knowledge of leaf rust resistance genes in Canadian wheat and their utilization in resistance breeding.</p

Table_1_Genetic mapping of leaf rust (Puccinia triticina Eriks) resistance genes in six Canadian spring wheat cultivars.docx

The Canada Western Red Spring wheat (Triticum aestivum L.) cultivars AAC Concord, AAC Prevail, CDC Hughes, Lillian, Glenlea, and elite line BW961 express a spectrum of resistance to leaf rust caused by Puccinia triticina Eriks. This study aimed to identify and map the leaf rust resistance of the cultivars using three doubled haploid populations, AAC Prevail/BW961 (PB), CDC Hughes/AAC Concord (HC), and Lillian/Glenlea (LG). The populations were evaluated for seedling resistance in the greenhouse and adult plant disease response in the field at Morden, MB for 3 years and genotyped with the 90K wheat Infinium iSelect SNP array. Genetic maps were constructed to perform QTL analysis on the seedling and field leaf rust data. A total of three field leaf rust resistance QTL segregated in the PB population, five in the HC, and six in the LG population. In the PB population, BW961 contributed two QTL on chromosomes 2DS and 7DS, and AAC Prevail contributed a QTL on 4AL consistent across trials. Of the five QTL in HC, AAC Concord contributed two QTL on 4AL and 7AL consistent across trials and a QTL on 3DL.1 that provided seedling resistance only. CDC Hughes contributed two QTL on 1DS and 3DL.2. Lillian contributed four QTL significant in at least two of the three trials on 2BS, 4AL, 5AL, and 7AL, and Glenlea two QTL on 4BL and 7BL. The 1DS QTL from CDC Hughes, the 2DS from BW961, the 4AL from the AAC Prevail, AAC Concord, and Lillian, and the 7AL from AAC Concord and Lillian conferred seedling leaf rust resistance. The QTL on 4AL corresponded with Lr30 and was the same across cultivars AAC Prevail, AAC Concord, and Lillian, whereas the 7AL corresponding with LrCen was coincident between AAC Concord and Lillian. The 7DS and 2DS QTL in BW961 corresponded with Lr34 and Lr2a, respectively, and the 1DS QTL in CDC Hughes with Lr21. The QTL identified on 5AL could represent a novel gene. The results of this study will widen our knowledge of leaf rust resistance genes in Canadian wheat and their utilization in resistance breeding.</p

High density mapping and haplotype analysis of the major stem-solidness locus <i>SSt1</i> in durum and common wheat

<div><p>Breeding for solid-stemmed durum <i>(Triticum turgidum</i> L. var <i>durum</i>) and common wheat (<i>Triticum aestivum</i> L.) cultivars is one strategy to minimize yield losses caused by the wheat stem sawfly (<i>Cephus cinctus</i> Norton). Major stem-solidness QTL have been localized to the long arm of chromosome 3B in both wheat species, but it is unclear if these QTL span a common genetic interval. In this study, we have improved the resolution of the QTL on chromosome 3B in a durum (Kofa/W9262-260D3) and common wheat (Lillian/Vesper) mapping population. Coincident QTL (LOD = 94–127, <i>R</i>^<i>2</i> = 78–92%) were localized near the telomere of chromosome 3BL in both mapping populations, which we designate <i>SSt1</i>. We further examined the <i>SSt1</i> interval by using available consensus maps for durum and common wheat and compared genetic to physical intervals by anchoring markers to the current version of the wild emmer wheat (WEW) reference sequence. These results suggest that the <i>SSt1</i> interval spans a physical distance of 1.6 Mb in WEW (positions 833.4–835.0 Mb). In addition, minor QTL were identified on chromosomes 2A, 2D, 4A, and 5A that were found to synergistically enhance expression of <i>SSt1</i> to increase stem-solidness. These results suggest that developing new wheat cultivars with improved stem-solidness is possible by combining <i>SSt1</i> with favorable alleles at minor loci within both wheat species.</p></div

Phenotypic distribution of percent loose smut incidence (LSI, %) for the Strongfield/Blackbird DH mapping population in response to <i>Ustilago tritici</i> individual races T26, T32 and T33.

<p>Percent loose smut incidence levels for parents Blackbird and Strongfield are indicated by ‘B’ and ‘S’, respectively.</p

A QTL for loose smut resistance detected on chromosome 6B.

<p>A region of the chromosome 6B genetic map showing the position of SNP and SSR markers and highly significant QTL (<i>QUt</i>.<i>spa-6B</i>.<i>2</i>) associated with resistance to multiple races (T26, T32 and T33) of <i>Ustilago tritici</i>. Markers associated with the QTL are shown in green to the left of the double line representing the chromosome and their positions along the map are given to the right. A thick and multi-colored vertical line below the QTL peaks represents the genome-wide LOD threshold values (range 3.28–3.55) for declaring significant QTL.</p

Phenotypic distribution of percent loose smut incidence (LSI, %) for the Strongfield/Blackbird DH mapping population in response to a mixture of <i>Ustilago tritici</i> races T26, T32 and T33.

<p>Percent loose smut incidence levels for parents ‘Blackbird’ and ‘Strongfield’ are indicated by ‘B’ and ‘S’, respectively. H1 represents head 1 and H2 represents head 2.</p

Synergistic two-way interactions between <i>SSt1</i> and minor QTL identified in the Kofa/W9262-260D3 (durum) and Lillian/Vesper (common wheat) mapping populations.

<p>Synergistic two-way interactions between <i>SSt1</i> and minor QTL identified in the Kofa/W9262-260D3 (durum) and Lillian/Vesper (common wheat) mapping populations.</p

Haplotypes of 103 durum cultivars within the Kofa/W9262-260D3 <i>SSt1</i> QTL interval.

<p>Stem-solidness LS means for each line are shown in the bar chart along the top X-axis. The matrix consists of 90K genotypic data where cells shaded in blue denote expression of the W9262-260D3 (solid-stem) allele, whereas cells shaded in red denote expression of the Kofa (hollow-stem) allele. The name and position of each 90K probe, the anchored physical position on WEW chromosome 3B, and the corresponding position on the common wheat consensus map are shown. Two dimensional (row and column) hierarchical cluster analysis was performed to group lines into haplotypes as indicated by the colorized dendogram along the top X-axis, whereas similarly marker order is shown along the left Y-axis. *Lines showing identical haplotypes (n = 45) were collapsed into a single haplotype (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0175285#pone.0175285.s002" target="_blank">S2A Table</a>).</p

Summary of composite interval mapping (CIM) results.

<p>QTL were localized in the Kofa/W9262-260D3 (durum) and Lillian/Vesper (common wheat) mapping populations.</p

Frequency histograms displaying least-square means for stem-solidness.

<p>Scores are averaged across testing environments for DH lines in a) Kofa/W9262-260D3 (durum), and b) Lillian/Vesper (common wheat) mapping populations.</p