Genome-wide DNA Variants Identify Genetic Diversity and Population Structure of Leptosphaeria maculans in Western Canada
Bibliographic record
Abstract
Abstract Background: Leptosphaeria maculans is a serious concern for canola production in Canada. For effective management, knowledge of the pathogen’s genetic variability and population structure is a prerequisite. Despite some information on race dynamics of the western Canadian L. maculans population in recent years, genetic diversity based on a large number of genome-wide DNA variants has not been investigated.Results: From 1,590 L. maculans isolates collected from 23 field sites in three provinces: Manitoba, Saskatchewan and Alberta, Canada, in the years 2007-2008 and 2012-2014, 150 representative isolates were selected and whole-genome sequenced, and 31,870 polymorphic DNA variants (SNPs and InDels) were used to study L. maculans genetic diversity and population structure. Cluster analysis showed that the genetic diversity levels and isolate groupings varied with the number and genomic regions of the variants involved; isolates collected in 2012-2014 were more genetically diverse than those collected in 2007-2008 when genome-wide variants were considered. The genome wide association study (GWAS) detected variants in egn4_Lema_T86290 (AvrLm4-7), egn4_Lema_T86300 and egn4_Lema_T86310 associated with the year of collection, but no variants was found to be associated with the province or specific location from which the isolates were collected. Population structure analysis indicated the presence of three distinct sub-populations in western Canada. While isolates from Saskatchewan were mainly of one sub-population (sub-pop1), the Alberta isolates comprised two sub-populations (sub-pop1 and sub-pop2), and all the 3 subpopulations were found in Manitoba.Conclusion: The genetic diversity of the western Canadian L. maculans population varied among provinces. It was highly admixed in Manitoba, followed by that in Alberta. The Saskatchewan population had the lowest genetic diversity. Significant genome variation between 2007-2008 and 2012-2014 occurred in the genes egn4_Lema_T86290 (AvrLm4-7), egn4_Lema_T86300 and egn4_Lema_T86310), with AvrLm4-7 becoming much more common in the L. maculans population in the later period.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".