Strains of <i>Leptosphaeria maculans</i> with the Capacity to Cause Crown Canker on <i>Brassica carinata</i> are Present in Western Australia
Bibliographic record
Abstract
Blackleg, caused by Leptosphaeria maculans (Desm.) Ces. et de Not., is the most important disease of canola (Brassica napus L.) in Australia, Europe, Canada, and North America (2). During the early 1990s, new cultivars of canola with resistance to blackleg were released in Australia. Despite good adult-plant resistance, these cultivars still suffered significant yield losses from blackleg under high disease pressure. Potential new sources of blackleg resistance such as B. nigra L., B. carinata L., and Sinapis alba L. are being evaluated. B. carinata is believed to be highly resistant to blackleg by virtue of its B-genome. However, some L. maculans isolates that can attack B. carinata have been reported from Germany (1). During the 2003 growing season, 22 isolates of L. maculans were collected from different canola-growing areas of Western Australia and tested for their reaction on 24 seedlings of each of various Brassica genotypes, including B. carinata, in a controlled environment chamber. Twenty-four seeds per genotype were sown in 100-ml plastic pots (12 seeds per pot) and both cotyledons of 10-day-old seedlings were wound inoculated with a conidial suspension (1 × 107 conidia/ml) of each isolate of L. maculans. Disease assessments were made 2 weeks after inoculation. The majority of isolates induced a noninvasive hypersensitive reaction on B. carinata without pycnidial development. However, four of the isolates caused lesions with abundant pycnidia on B. carinata cotyledons. The lesion size ranged between 3 and 7 mm and appeared similar to that on susceptible B. napus cultivars. B. carinata seedlings were grown for another 8 weeks in a glasshouse, and crown cankers were observed from plants inoculated with three of the four seedling virulent isolates. The severity of crown cankers as percent of stem circumference (percent disease index) ranged between 20 and 54%. Twenty-five stem pieces from mature B. carinata plants infected with one of the three isolates were plated on V8 juice agar and L. maculans was recovered from 70% of pieces. Abundant pycnidia were also observed on these stem pieces. These results have important implications for using B. carinata as a source of blackleg resistance in canola breeding. To our knowledge, this is the first report of L. maculans isolates with the capacity to induce crown cankers on B. carinata in Australia. References: (1) C. Sjöidin and K. Glimelius. J. Phytopathol. 123:322, 1988. (2) J. West et al. Plant Pathol. 51:454, 2002.
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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 | 0.000 |
| 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) | 0.001 | 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".