Modeling blackleg severity and incidence in canola and identification of molecular markers linked to a Leptosphaeria maculans avirulence gene
Bibliographic record
Abstract
Canola is the most important oilseed crop in Canad,a.Blackleg caused by Leptosphøeria maculans is the rnost important disease in canola in the prairie provinces.While the sexual spores have been implicated as primary inoculum, there has not much work done on the asexual pycnidiospores and their role in primary infection in Canada.With the frnding of new blackleg pathogenicity groups in the prairies, there has been renewed interest in understanding the host-pathogen interactions, and the role of R-genes and corresponding avirulence genes in the pathogen.Therefore, the two main goals of the epidemiolo gy part of this study were to investigate the role of pycnidiospores of Leptosphaeria maculans ondisease development on plants infected at the cotyledon (i.0), 3-leaf (1, 03) and 6-leaf (1, 06) stages of Brassica napus cvs.Westar and Q2 under field conditions and to develop nonlinear weather-based models to describe blackleg severity and incidence of the infected plants.The results suggested that pycnidiospores were a source of primary inoculum for 2004 and 2005.The results showed that the mean blackleg severity of the plants infected at the cotyledon stage was significantly higher than plants infected at the other two stages.These results also confirmed that the mean blackleg severity of the plants infected at the 3-leaf stage was higher than plants infected at the 6-leaf stage.Blackleg incidence in the plants infected at the cotyledon stage was significantly higher than the other two stages.No signifìcant difference in disease incidence was observed between the plants infected al3-leaf and 6-leaf stage.Pearson's correlation coefficient showed that two weather variables, total rainfall per week (R) and average maximum temperature per week (Tmøx), werc significantly An atternpt was also made to develop molecular markers for the corresponding avirulence gene in L. mqculans to the LepRI resistance gene in B. napus, and to obtain fuither evidence of a gene-for-gene interaction.The segregation of 94 F1 progen! of Z.maculans from a cross of avirulent isolate (99-56) and virulent isolate (g7-41) on the monogenic line ddm-126s-1 containing LepRI was studied.The progenies were isolated and phenotyped for reactions on the line ddm-1 26s-1.The population segregated in 1 :1 ratio,44 avirulent and 50 virurent d : 0.79, p :0.66), indicating single gene contror of 99-56 avirulence on dm-726s-1.Bulked segregant analysis was used to identiflz two IV Sequence-related amplified polymorphic (SRAP) markers closely linked to the avirulence gene.We have named this avirulence gene AvrLepRI.Two flanking SRAP markers, SA7-108 and SA7-490, were linked to AvrLepRI at 9.6 and 7.8 cM, respectively.This work present further evidence for a gene-for-gene rnodel which has been suggested previuosly in this pathosystem and represents an initial step toward map-based cloning of this gene.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".