Basidiomycetous endophytes in jungermannialean (leafy) liverworts have novel cytology and species-specific host ranges: a cytological and experimental study
Bibliographic record
Abstract
This article reviews published data on the likely occurrence of basidiomycetous endophytes in jungermannialean (leafy) liverworts and presents a new overview based on observations on freshly collected specimens supplemented with confirmation, by transmission electron microscopy, of dolipore septa in representative taxa. These associations are widespread in the Lophoziaceae and Arnelliaceae and sporadic in the Jungermanniaceae, Scapaniaceae, and Geocalycaceae. They are almost exclusively confined to taxa growing on well-drained, humus-rich substrata and are absent from epiphytes and species from bare rocks and waterlogged habitats. Cross-infection experiments between axenically cultured liverworts ( Lophozia , Nardia , Diplophyllum , Southbya , and Aneura in the Metzgeriales) and their mycobionts revealed the associations to be host specific, in striking contrast with the wide host ranges previously recorded for rhizoidal ascomycetes in the Cephaloziaceae and other families. More vigorous growth of resynthesized basidiomycete associations compared with their axenic counterparts is indicative of nutritional benefits to the liverworts. The fungi enter their hosts via the tips of the rhizoids and develop distinctive distributions within the liverwort stem. In the Arnelliaceae, this comprises a central medullary strand; in the Lophoziaceae and Scapaniaceae, the ventral medulla contains a mosaic of infected and noninfected cells. In the latter, pegs of host wall material overgrow penetrating hyphae. Electron microscopy revealed that all of the endophytes have straight imperforate parenthesomes typical of heterobasidiomycetes. The fungi form hyphal coils that outlive the host cytoplasm, and digestion of the mycobionts, as seen in Aneuraceae and orchidaceous mycorrhizas, are absent. Closely similar mosaic infection patterns in Lophoziaceae and Scapaniaceae strenghten the link between the two families based on molecular data, but the present cross-infection and ultrastructural data indicate that the Calypogeia endophyte is ascomycetous rather than a member of the Sebacinaceae as reported previously. The distribution of basidiomycete associations in liverworts suggests that these probably arose several times and are more recent in origin than associations with glomeromycotean fungi.
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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 | 0.000 | 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".