Identification and genetic mapping of resistance genes against Canadian pathotypes of Plasmodiophora brassicae in Brassica rapa and Brassica napus
Bibliographic record
Abstract
Clubroot (Plasmodiophora brassicae) is an important disease of canola/rapeseed (Brassica napus) and other crucifers. In this study, resistance loci/genes effective against P. brassicae pathotypes 2B, 3A, 3D, 3H, 5C, 5X and 8J were identified and mapped via genotyping-by-sequencing, QTL analysis, conventional linkage mapping, and by exploring the effect of individual genes on quantitative traits in combination with marker and trait data. Four of 34 B. napus accessions, CGN06902, CGN17369, AAFC695, and CN46235, were resistant to pathotypes 3A, 2B, and 3D, while 16 B. rapa families did not show any resistance. The resistant accession AAFC695, B. napus ‘Mendel’ (resistant to 13 of 17 pathotypes identified on the Canadian Clubroot Differential set), and B. rapa line ECD02 (resistant to all 17 pathotypes) were used to map resistance genes by developing a BC1S1 population based on ECD02 and doubled haploid (DH) populations based on ‘AAFC695’ and ‘Mendel’. A single QTL Rcr9ECD02 was identified on chromosome A08 of ECD02 using 93 BC1S1 lines; this QTL conferred resistance to pathotypes 3A, 3D, 3H, and 5X, accounting for 68.9-74.4% phenotypic variation explained (PVE). Bulked segregant and KASP analysis confirmed the QTL. In ‘AAFC695’, a QTL Rcr9AAFC695 was identified on chromosome A08 using 102 DH lines; Rcr9AAFC695 explained 92.6-95.0% PVE in response to pathotypes 3A, 3D, 3H, and 5X, with LOD values of 60.3 to 70.8. In ‘Mendel’, the QTL Rcr3Mendel was mapped on chromosome A08 using 137 DH lines; this was a major locus explaining 88-90% PVE for resistance to pathotypes 3D, 5C, and 8J, with an additive effect of 47.2-47.3%. Testing of 60 lines from this population against pathotype 3H indicated that Rcr3Mendel is the Rcr3 locus, but that it also bestows resistance to pathotypes 3D, 5C, and 8J. The identification of TIR_NBS_LRR (TNL) genes (via analysis of gene annotation with Blast2GO and gene ontology information) in the QTL regions of the three populations confirmed that the identified QTL Rcr9ECD02, Rcr9AAFC695 and Rcr3Mendel are different from each other, and distinct from Rcr9. The CR loci/genes identified in this study will enrich the repository of resistance genes available to protect canola/rapeseed from clubroot disease.
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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".