Molecular Phylogenetic Support from Ribosomal DNA Sequences for Origin of Helminthosporium from Leptosphaeria-like Loculoascomycete Ancestors
Bibliographic record
Abstract
Internal transcribed spacer (ITS) regions and 5.8S rDNA were PCR-amplified and sequenced for 17 isolates of Helminthosporium solani, cause of the potato disease silver scurf, and for 10 other isolates obtained from culture collections as Helminthosporium spp. Of these, five isolates had been incorrectly identified as Helminthosporium spp. and belonged in the genera Cochliobolus (anamorphs Bipolaris, Curvularia), Cladosporium, and Pyrenophora (anamorph Drechslera). Sequence alignment and analyses of ITS regions and 5.8S rDNA of four true Helminthosporium species and more than 45 fungi formerly grouped in the genus Helminthosporium s. l. revealed that the segregated Helminthosporium species did not group with Helminthosporium s. s. Three species of Helminthosporium s. s. (H. solani, type species H. velutinum, and H. chlorophorae) grouped tightly and were most closely related to the teleomorph Leptosphaeria bicolor. For H. solani and H. velutinum, 18SrDNA sequences were also determined. Phylogenetic analyses of the 18S rDNA sequences of 33 euascomycetous species confirmed the close relationship of H. solani and H. velutinum to L. bicolor and placed Helminthosporium in the Pleosporales with 100% parsimony bootstrap support. Helminthosporium asterinum did not group closely with the other species of Helminthosporium s. s., but was as closely related to discomycetes in the Leotiales as to other true Helminthosporium spp. Review of type material revealed that H. asterinum could be excluded from the genus Helminthosporium based on morphology.
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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 | 0.001 | 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 | 0.001 |
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".