Identification of the Phytoplasma Associated with Wheat Blue Dwarf Disease in China
Bibliographic record
Abstract
Wheat blue dwarf disease (WBD) was first reported in China in the 1960s. It has caused severe losses on several occasions in winter wheat (Triticum aestivum) in northwestern China, and the nature of the pathogenic agent has been unknown. Here we have shown that WBD was caused by a 16SrI-C phytoplasma transmitted by Psammotettix striatus. This finding was based on molecular diagnostics, insect transmission trials, and host-range determination. Portions of the 16S rRNA and ribosomal protein (rp) genes, rpsS (rps19), rplV (rpl22), and rpsC (rps3), were amplified from DNA samples of WBD-infected wheat seedlings by polymerase chain reaction (PCR) utilizing phytoplasma specific primer pairs. The nucleotide sequences of these amplicons showed high identity to these genes from phytoplasma strains in the aster yellows group (16SrI). Pairwise nucleotide sequence identities of WBD 16S rDNA compared to representative genes of 16SrI group strains ranged from 98.9 to 99.9%, whereas compared to 17 other phytoplasma groups (16SrII to 16SrXVIII), sequence identity ranged from 88.6 to 96.0%. Similarly, the sequence identities of rps19, rpl22, and rps3 between WBD and 16SrI group strains varied from 96.6 to 99.7%, but only 60.3 to 65% between WBD and other phytoplasma groups. Phylogenetic analyses were carried out on sequences from 16S rRNA and ribosomal protein genes (rps19, rpl22, and rps3), respectively, and both results indicated that WBD phytoplasma was a member of the 16SrI group and most closely related to subgroup 16SrI-C. WBD-infected P. striatus were present in wheat fields with WBD, and phytoplasma infection was verified by PCR detection followed by DNA sequencing. Insect transmission trials confirmed that P. striatus transmitted the WBD phytoplasmal agent from infected wheat to healthy wheat seedlings and seven other different plant species in the greenhouse. A survey of various weed species near WBD-infected wheat fields found 10 plant species in seven families to be positive for the presence of WBD phytoplasma.
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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 | 0.001 | 0.001 |
| 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 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".