First report of a phytoplasma affecting cassava orchards in Cote d'Ivoire.
Bibliographic record
Abstract
Cassava (Manihot esculenta) is one of the staple foods in Africa, cultivated in around 40 countries and producing more than three million tonnes every year (United Nations, 3). In Côte d'Ivoire, cassava production is second to yams, and it is widely used as a typical food side dish called 'attieké'. Moreover, cassava-based flour or starch is widely used by private companies, which has made cassava one of the most important Ivorian industrial crops. Cassava has become an alternative income source for women in the south littoral of the coconut-growing area of Grand-Lahou, since the Côte d'Ivoire lethal yellowing phytoplasma (CILY, 16SrXXII-B, 'Candidatus Phytoplasma palmicola-related strains') devastated over 400 hectares of coconut plantations (Arocha et al., 1). Recently, symptoms of leaf mosaic, curling and yellowing (Figs. 1-2) were observed in cassava orchards located in the coconut-growing villages of Badadon and Braffedon in Grand-Lahou, which are currently affected by CILY. Leaf samples were collected at random from 12 symptom-bearing and two symptomless cassava plants from the two villages. Total DNA was extracted and used as a template for a nested PCR assay with universal primers that target the phytoplasma 16S rRNA gene, R16mF2/R1 for the first PCR reaction, and R16F2n/R2 for the nested reaction (Gundersen & Lee, 4). A second PCR assay was performed with primers P1 (Deng & Hiruki, 2) and P7 (Schneider et al., 5) followed by a nested PCR with primers G813 and AwkaSR (Tymon et al., 6) that specifically target the 16S rRNA gene and part of the intergenic region 16/23S rRNA gene of the Cape St. Paul Wilt Disease phytoplasma (16SrXXII-B) from Ghana. R16F2n/R2 and G813/AwkaSR amplicons were produced from six of the 12 symptom-bearing samples but not from the two symptomless plants. R16F2n/R2 amplicons from each sample were purified (EZNA Cycle Pure Kit, Omega Bio-Tek, USA), cloned (pGEM-T Easy Vector, Promega), and sequenced (University of Toronto, Canada). A consensus sequence was deposited in GenBank (Accession No. KY563222), and was compared to those of other phytoplasmas in the database and analysed through iPhyclassifier (http://plantpathology.ba.ars.usda.gov). R16F2n/R16R2 sequences from all samples shared 100% sequence identity and were 99% similar to those of the 16SrXXII-B phytoplasmas, including the CILY phytoplasma (KC999037). Analysis of the R16F2nR2 sequences with iPhyclassifier and the pDRAW32 software (http://www.acaclone.com) showed that the Côte d'Ivoire cassava phytoplasma and the CILY phytoplasma KC99937, exhibited identical AluI, RsaI, TaqI, HaeIII, BstUI, KpnI, HhaI, HinfI, HpaI, HpaII, MseI, Sau3AI, DraI, and BfaI RFLP profiles. Phylogenetic analysis (MEGA 4.0) based on the 16S rDNA sequence (Fig. 3) supported the grouping of the Côte d'Ivoire cassava phytoplasma within the 16SrXXII-B cluster, closely related to ‘Ca. P. palmicola’ (16SrXXII-A). To our knowledge this is the first report of a phytoplasma affecting cassava in Côte d'Ivoire. The findings suggest that cassava may be a potential alternative host for the CILY phytoplasma, which poses a serious threat for the food security of the smallholder coconut and cassava farmers, especially women in Grand-Lahou, Côte d'Ivoire.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| 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".