First Report on the Presence of Phoma Blackleg Pathogenicity Group 1 (<i>Leptosphaeria biglobosa</i>) on <i>Brassica napus</i> (Canola/Rapeseed) in Iran
Bibliographic record
Abstract
Canola/rapeseed (Brassica napus L.) is a new crop in Iran, grown since 1996. In 2006, 180,000 ha were planted. During the same year, leaf and upper stem lesions (3) were observed on cv. Hyola 401 at rosette and flowering stages in the Gorgan Province in northern Iran. Field disease incidence ranged from 1 to 40%. Several isolates from stem lesions were sent to the Department of Plant Science, Blackleg Research Lab, University of Manitoba, Canada from the Agricultural and Natural Resources Research Center of Golestan Province of Iran for pathogenicity group identification. The blackleg pathogen is divided into several pathogenicity groups on the basis of phenotypic interaction (IP) of isolates on differential cvs. Westar, Glacier, and Quinta. Isolates PG2, PG3, PG4, and PGT are highly virulent, but PG1, which recently has been named Leptosphaeria biglobosa (2), is weakly virulent. Colonies of the blackleg pathogen were reisolated from their original medium, potato dextrose agar, and grown onV8 agar medium and incubated under light for 2 weeks. Pure cultures of the pathogen were then characterized by colony morphology, pycnidia, and measurement and microscopic observation of pycnidio-spores. Fungal colonies formed with concentric rings containing pycnidia with pink ooze on V8 agar. Pycnidia were globose and as much as 200 μ 200 μm. They had a prominent beak on the ascomata that was enlarged, cylindrical, central, terete, erect, and 150 to 200 × 100 μm. Pycnidiospores were cylindrical, straight, 4 to 5 × 2 μm, and hyaline (2). To identify the pathogenicity group of the Iranian isolates, pycnidiospores were harvested from single-spore cultures after 14 days of incubation under continuous cool-white fluorescent light (1). One-week-old cotyledons from the differential cvs. Westar, Glacier, and Quinta were inoculated with pycnidiospore suspension concentration of 2 × 107 spores per ml of the four Iranian isolates. Each cotyledon lobe was punctured with forceps and inoculated with a 10-μl droplet of spore suspension. Disease evaluations were made 10 to 14 days after inoculation using a 0 to 9 rating scale. Inoculations were repeated twice with identical results yielding only the PG1 type reaction. To our knowledge, this is the first report of the presence of L. biglobosa (PG1; B-type) on canola in Iran. Differential testing fulfilled Koch's postulates. L. biglobosa seems to be less damaging compared with L. maculans, but severe phoma stem lesion epidemics have been associated with the L. biglobosa in Poland (3). The importance of this weakly virulent pathogen, whenever the relative humidity increases, has been demonstrated in greenhouse conditions (A. El-Hadrami, W. G. D. Fernando, and F. Daayf, unpublished data). Since the relative humidity in northern Iran is high, an epidemic may occur if appropriate management practices are not utilized to minimize inoculum levels. References: (1) W. G. D. Fernando and Y. Chen. Plant Dis. 87:1268, 2003. (2) R. A. Shoemaker and H. Brun. Can. J. Bot. 79:412, 2003. (3) J. S.West et al. Plant Pathol. 48:161, 2001.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 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".