First report of a phytoplasma associated with Australian lucerne yellows disease
Bibliographic record
Abstract
Lucerne or alfalfa (Medicago sativa) is a pasture legume of worldwide significance. The production of lucerne seed is an important sector of Australia’s pasture seed industry, but is being affected by the disease Australian lucerne yellows (ALuY) (Pilkington et al., 1999). Symptoms associated with ALuY include a discoloration of leaves (Stovold, 1983) ranging from bright yellow to red. Discoloration is consistently evident across the entire foliage of the plant (Pilkington et al., 1999). Further symptoms include a characteristic brown discoloration immediately under the periderm of the tap root (Stovold, 1983). Phytoplasmas are known to cause similar yellowing symptoms in other crops, such as grapevine yellows (Padovan et al., 1995). Using transmission electron microscopy (TEM), phytoplasmas were found in phloem of leaf midrib and stems prepared from infected plants, and were absent from similar tissue of healthy (symptomless) plants. The structures visualized by TEM in ALuY-affected plant tissue were consistent in size, shape and structure with phytoplasmas associated with other plant diseases (Gowanlock et al., 1998). Fifty individual symptomatic lucerne plants were tested using polymerase chain reaction techniques, with approximately 40% of individuals testing positive for the presence of a phytoplasma. Fifteen nonsymptomatic plants were tested using identical techniques, with no positive results. A phytoplasma was shown to be associated with Australian lucerne yellows, although it may not be the exclusive causal agent. Analysis of ALuY 16S rDNA revealed this strain to be closely related phylogenetically to Australian tomato big bud phytoplasma. We thank the Rural Industries Research and Development Corporation for providing funding for this work, Mr Don Gowanlock (University of Queensland) for his aid in interpretation of the electron micrographs, and Dr Deborah Hailstones (NSW Agriculture) and Lucy Tran-Nguyen (Northern Territory University) for their aid in molecular biology techniques.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 teacher head, 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".