Genetic diversity of phytoplasmas identified in peach (Prunus persica) accessions at the Canadian Clonal Genebank.
Bibliographic record
Abstract
Peach [Prunus persica (L.) Bastch] is mainly cultivated in Canada in Ontario province (82% of national production). A variety of symptoms typical of a phytoplasma infection were observed some of the 83 P. persica accessions during June-August 2009 at the Canadian Clonal Genebank. PRU0430 (‘HW274’, from Canada), PRU0380 (‘GF305’ from France), PRU0334 (‘RedSkin’ from USA), PRU0155 (‘Harblaze’, from Canada) and PRU0375 (‘Babygold #5’, from USA) showed decline, leaf reddening, yellowing, shortening of internodes, witches’ broom and reduced fruit size; while ‘PRU0382’ (peach-almond ‘Kando’ from the Czech Republic) and PRU0445 (peach ‘HW271’ from Canada) exhibited peach rosette-like symptoms. Leaf samples from symptomatic and symptomless plants were collected and total DNA was extracted. Phytoplasma universal 16S rRNA primers, R16mF2/R1 and R16F2n/R2 and fU5/rU3 were used in nested PCR assays. R16F2n/R2 nested PCR products were obtained for ‘PRU0430’, ‘PRU0380’, ‘PRU0155’, ‘PRU0334’ and ‘PRU0375’; while fU5/rU3 PCR products were obtained for ‘PRU0382’ and ‘PRU0445’. Plants lacking symptoms yielded no PCR products. Amplicons were purified, cloned, and sequenced. BLAST analysis showed that R16F2n/R2 sequences (GU223903) were 99% identical to 16S rRNA phytoplasma sequences for group 16SrVII ‘Candidatus Phytoplasma fraxini’, while those from fU5/rU3 amplicons (GU223904) shared 99% identity with those of group 16SrI ‘Candidatus Phytoplasma asteris’. AluI, RsaI and MseI RFLP analysis yielded profiles consistent with those of phytoplasma in subgroups 16SrVII-A and 16SrI-B, respectively. To our knowledge, this is the first report of a 16SrI-related phytoplasma in peach in Canada, and the first world report of a 16SrVII-related phytoplasma strain identified in peach after a case in southern Italy.
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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 | 0.002 | 0.003 |
| Science and technology studies | 0.002 | 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) | 0.002 | 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".