characterization and genetic mapping of leaf rust (Puccinia triticina) resistance genes Lr2a and Lr46 in Canadian spring wheat (Triticum aestivum) germplasm
Bibliographic record
Abstract
Of the fungal diseases that can infect bread wheat (Triticum aestivum L.), leaf rust, caused by Puccinia triticina Eriks. is the most common and widespread. Pyramiding multiple resistance genes in a cultivar using conventional breeding techniques is often expensive and time consuming. Alternatively, marker assisted selection (MAS) allows for accelerated and accurate selection of resistance gene combinations. The objectives of this study were to characterize two leaf rust resistance genes: an adult plant resistance (APR) gene, hypothesized to be Lr46, from wheat line BW278, and a seedling resistance gene, Lr2a, from wheat cultivar Superb. To characterize the APR, two mapping populations derived from BW278 were genotyped with the iSelect 90K wheat SNP array. Both populations were evaluated for leaf rust in inoculated field nurseries for five years. Quantitative trait locus (QTL) analysis revealed two QTL controlling resistance in the BW278/AC Foremost population, one in the region of interest, chromosome 1B and another on chromosome 5A. Two QTL were detected in Superb/BW278, on chromosomes 4B and 5B, however no QTL were detected in the region of interest on 1B. The QTL on 1B in BW278/AC Foremost, designated QLr.mrdc-1B, was tightly linked to both csLV46G22 and DK0900, two markers previously described as tightly linked to the Lr46 locus. Ten SNPs in the QLr.mrdc-1B region were selected for kompetitive allele-specific PCR (KASP) assay design. To characterize Lr2a, two mapping populations derived from Superb (Superb/BW278 & Superb/86ISMN 2137) were genotyped with the iSelect 90 K wheat SNP array, and evaluated with a single race of P. triticina under greenhouse conditions. Two-point linkage analysis between the marker data and phenotypic infection type ratings revealed that the gene mapped to chromosome 2DS in both mapping populations. The linkage maps generated for the two mapping populations had 11 SNP markers in common and displayed collinearity. Seven SNPs that either flanked or co-segregated with Lr2a in Superb/BW278 were selected for KASP assay design. Of the seven markers, kwh740 (Excalibur_c1944_1017) was polymorphic in both populations and displayed clear clusters, making it the most applicable for use in MAS.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".