Mapping of Ug99 stem rust resistance in Canadian durum wheat
Bibliographic record
Abstract
Stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), has potential to cause major yield losses in durum wheat. Development of durum cultivars with improved resistance to stem rust is a sustainable option for effective control of this disease. This study was conducted to identify genomic regions associated with resistance to Ug99-derived Pgt races using a doubled haploid (DH) mapping population produced from a cross between the resistant experimental line A9919-BY5C and the moderately susceptible cultivar ‘Strongfield’. The parents and DH lines were phenotyped for adult plant disease severity and infection response at Njoro, Kenya, for four years, and for seedling reaction to race TTKSK in a containment facility near Morden, Canada. Composite interval mapping using 612 SNP and DArT markers indicated four significant QTL for resistance to stem rust on chromosomes 1B, 4A, 5B, and 6A. A major and stable QTL from A9919-BY5C was identified on the short arm of chromosome 6A (6AS), which accounted for 71% of variation explained for seedling resistance and up to 46% for field resistance. This QTL mapped near the Sr8 locus and may be Sr8155B1, or a novel gene at the same location. Another QTL for adult plant resistance from A9919-BY5C was mapped on chromosome 1B that explained up to 14% of the phenotypic variation and likely is Sr14. Two minor QTL were identified in ‘Strongfield’ on chromosomes 4A and 5B that were inconsistent over years. Markers associated with the 6AS and 1B QTL can be used to proactively stack resistance to Ug99-derived races of Pgt into Canadian durum wheat.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 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) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".