First Record of White Rust, Caused by <i>Albugo occidentalis</i>, on Spinach in Greece
Bibliographic record
Abstract
In early December 2012 and February 2013, severe symptoms of white rust were observed on several commercial crops of the spinach (Spinacia oleracea L.) cvs. Tahiti and Rembrandt in the Aghia Pelaghia and Elia areas, respectively, of Heraklio, Crete, Greece. Initially, small, chlorotic lesions developed on the upper side of the leaves. As disease progressed, small, glassy white pustules developed on the underside of each leaf, frequently in concentric rings. The pustules were blister-like and oval, irregularly oval, or elongated, ranging from 0.5 to 2.0 mm in diameter and up to 3 mm in length. Lesions often coalesced, and the pustules could cover the entire lower leaf surface, rendering them unmarketable. The dome-like epidermis of host tissue covering the white rust pustules ruptured and exposed a white, chalky ‘dust’ of numerous powdery spores in small, circular to elongate sori. The sporangia were arranged in basipetal chains, were globose to oval, with a smooth wall that was uniformly thick and measured 19.1 ± 1.93 (14.1 to 23.5) μm × 15.3 ± 1.49 (12.9 to 20.0) μm when hydrated. Oospores were absent from the leaves. The morphological characteristics closely resembled those reported for the white rust pathogen, Albugo occidentalis Wilson (4), as well as those of A. occidentalis measured from dried leaves of Chenopodium spp. and Monolepis nuttalliana (Schult.) Greene (Herb. IMI96980, IMI351202, and IMI26345, respectively), kindly loaned by the Royal Botanic Gardens, Kew, United Kingdom. Pathogenicity was confirmed by spraying a suspension of 10 5 sporangia/ml on 10 healthy 20-day-old potted spinach plants of cv. Tahiti. Inoculated plants were covered with polyethylene bags for 3 days and incubated in a growth chamber at 16 to 20°C with a 10-h photoperiod. White rust symptoms were observed on the lower surface of the leaves 10 days after inoculation. Ten control plants sprayed similarly with distilled water and maintained under the same conditions as inoculated plants showed no symptoms. The fungus present on the inoculated plants was morphologically identical to that originally observed on diseased plants, fulfilling Koch's postulates. Genomic DNA from spinach leaf sori was extracted, and the internal transcribed spacer (ITS) region of ribosomal DNA (rDNA), ITS1-5,8S-ITS2, as well as the cytochrome oxidase subunit II (COX2) mitochondrial gene, were amplified. PCR products were sequenced and deposited in GenBank (KC676794 and KC676795, respectively). In a BLAST search, the ITS1-5,8S-ITS2 and COX2 sequences showed 99% similarities to 684 bp (AJ553900.1) and 599 bp (AY286220.1) sequences of the corresponding A. occidentalis genes in GenBank, respectively. Based on morphological characteristics, pathogenicity tests, and molecular sequencing data, it was concluded that the pathogen on spinach in Crete is A. occidentalis. This is an economically important pathogen of spinach in the United States, that has also has been recorded in Iran (2) and India on a Chenopodium sp. (IMI351202), and in Canada on M. nuttalliana (IMI26345). To our knowledge, this is the first report of this pathogen in Greece, and the first record on spinach in Europe. A voucher specimen has been deposited at the Royal Botanic Gardens, Kew, United Kingdom (Accession No. K(M) 181610). References: (1) J. C. Correll et al. Eur. J. Plant Pathol. 129:193, 2011. (2) A. G. Ebrahimi and H. Afzali. Rostaniha 1:73, 2000. (3) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN, 1989. (4) G. W. Wilson. Bull. Torrey Bot. Club 34:61, 1907.
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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".