Detection of <i>Citrus exocortis viroid, Iresine viroid</i>, and <i>Tomato chlorotic dwarf viroid</i> in New Ornamental Host Plants in India
Bibliographic record
Abstract
Columnea latent viroid, originating from ornamental plants, is known to be harmful to crop plants (2). Despite the potential threat to crop plants, the importance of ornamental plants in viroid evolution is not fully appreciated. Availability of a Pospiviroid genus-specific primer pair (1) to detect the most prevalent viroids in ornamental plants and a simplified nucleic acid preparation protocol (3) for use in reverse-transcription polymerase chain reaction (RT-PCR) have facilitated surveys of ornamental plants for pospiviroids. Using the above protocol in India, leaf and shoot samples were collected randomly from roadside beds consisting of ground covers or creepers/trailing plants at the IARI campus, New Delhi. These were extracted in 50 mM NaOH + 2.5 mM EDTA solution, centrifuged to sediment the coarse debris from sap, and 10 μl of the supernatant was spotted on a nitrocellulose membrane. Individual spots were eluted with distilled sterile water (30 μl) and the eluates were used for RT-PCR detection of viroids (3). Amplified fragments or subsequently cloned plasmids were also purified using NaOH-EDTA membrane protocol. Cloning and sequencing of amplicons (195 to 224 bp) revealed a very high sequence identity with specific viroids from the viroid sequence database (NCBI). Among the 19 plant samples assayed, only three plant species were infected by viroids, although none of them exhibited any symptoms. The three plant species included: (i) moss verbena, Glandularia puchella (Verbenaceae, native to Argentina and Chile, now established in several regions of the world), infected with a viroid (Accession No. DQ846884) having 99% sequence identity to Citrus exocortis viroid (CEVd) (Accession No. S67446); (ii) trailing verbena, Verbena × hybrida (Verbenaceae, ornamental plant), doubly infected with a viroid (Accession No. DQ846885) having 95% sequence identity to CEVd (Accession No. DQ094297) and infected with another viroid (Accession No. DQ846883) having 98% sequence identity to Tomato chlorotic dwarf viroid (TCDVd) (Accession No. AF162131); and (iii) red joyweed, Alternanthera sessilis (Amaranthaceae, a perennial weed herb) infected with a viroid (Accession No. DQ846886) having 96% sequence identity to Iresine viroid (IrVd) (Accession No. DQ094293). CEVd and TCDVd were mechanically transferred to tomato seedlings causing reduced growth of plants, smaller leaves, and bunchy-top appearance of plants, symptoms similar to those typically observed with other isolates of these viroids. As expected from previous studies, IrVd was not transmitted to tomato plants. Natural infection of verbena with CEVd has been detected in North America (2) but this was a novel observation in India. Additional novel observations include: A. sessilis as a new host for IrVd; and TCDVd is the first crop viroid to be isolated from a naturally infected ornamental plant. The significance of these viroid findings in ground cover and widely grown ornamental plants may lie in their potential role in spreading the viroids to citrus plants in citrus-growing countries such as India. References: (1) H. Bostan et al. J. Virol. Methods 116:189, 2004, (2) R. P. Singh and J. A. Teixeira da Silva. Floriculture, Ornamental Plant Biotechnol. 3:531, 2006. (3) R. P. Singh et al. J. Virol. Methods 132:204, 2006.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".