‘Brotes grandes’ (big bud) of potato: a new disease associated with a 16SrI‐B subgroup phytoplasma in Bolivia
Bibliographic record
Abstract
Potatoes are the main crop of smallholder farmers in the Valles Cruceños, Santa Cruz Province, Bolivia. During surveys carried out from 2000 to 2003, a disease locally known as ‘brotes grandes’ (BG, ‘big bud’), was prevalent on crops in the valleys of Chilon, Saipina, Pulquina and Comarapa, where up to 90% of plants were affected in some fields. Symptoms included tuber-like growths in leaf axils, varying in size and colour from red to purple or black and bearing terminal, adventitious leaves. Tubers often produced hair-like shoots, reducing their quality and yield. Previously, this syndrome was presumed to be rhizoctoniosis, caused by basal stem infection by Rhizoctonia solani (teleomorph, Thanatephorus cucumeris). However, R. solani was absent from all diseased plants examined in the present study. As other potato diseases similar to BG have been attributed to phytoplasmas in Australia (Harding & Teakle, 1993), Poland (Hamilton, 2000), Canada (Khadhair et al., 2003) and Mexico (Martínez-Soriano et al., 1999), tissues from Bolivian plants were indexed by nested PCR (nPCR) using phytoplasma universal rRNA primer pairs P1/P7 and R16F2n/R16R2. nPCR products resulting from 43/50 BG samples and digested separately with HaeIII, RsaI or AluI endonuclease all produced identical RFLP profiles. RFLP profiles of nPCR products amplified from three samples of the mora-mora vine (Serjania perulacea) with little-leaf symptoms in hedgerows surrounding potato fields in La Tranca, Santa Cruz Province, were indistinguishable from BG profiles. 16S rDNA sequences derived from PCR products shared 99% sequence homology among BG phytoplasmas. Sequences from the phytoplasmas obtained from potato (accession no. AY725209) and from S. perulacea (accession no. AY725210) were each very similar (98%) to that of ash witches’ broom phytoplasma (accession no. AY568302). This is the first report of a phytoplasma of the aster yellows (16SrI) group associated with a potato disease in Bolivia. Work in the UK was done under Defra plant health licence no. PHL 174B/4612(09/20003).
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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) | 0.000 | 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".