First Report of Verticillium Wilt caused by <i>Verticillium dahliae</i> Kleb. on New Zealand Spinach (<i>Tetragonia tetragonioides</i>) in Italy
Bibliographic record
Abstract
Tetragonia tetragonioides (New Zealand spinach, Aizoaceae) is an Australasian annual species that occurs naturally in Italy, where it is cultivated for the edible young shoots and succulent leaves. In September 2011, a previously unknown wilt was observed in 10 private gardens, each 0.1 to 0.5 ha, near Castellaro, Northern Italy, on 7-month-old New Zealand spinach plants. Leaves wilted, starting from the collar and moving up the plant, and vascular tissues showed brown streaks in the roots, crowns, and stems. Diseased plants were stunted with small, chlorotic leaves. Infected stems and leaves then wilted, and plants often died. Of about 500 plants, 30% were affected. Stems of 10 diseased plants were disinfected with 1% NaOCl for 1 min. Sections of symptomatic vascular tissue were plated on potato dextrose agar. After 3 days at 23 ± 1°C, colonies developed that were white and turned a grey to dark green color. Irregular, black microsclerotia (32.0) 63.1 ± 16.8 μm (106.1) × (18.7) 39.1 ± 12.3 μm (65.8) developed in hyaline hyphae after 8 days. Hyaline, elliptical, single-celled conidia (2.7) 3.8 ± 0.6 μm (4.8) × (1.9) 2.6 ± 0.5 μm (3.5) developed on verticillate conidiophores with three phialides at each node. Based on these morphological characteristics, the fungus was identified as Verticillium dahliae (1). The internal transcribed spacer (ITS) region of rDNA was amplified for one isolate using the primers ITS1/ITS4 (3) and sequenced (GenBank Accession No. JX308315). BLASTn analysis of the 479-bp segment showed 100% homology with the ITS sequence of a V. dahliae isolate (AB551206). Pathogenicity tests were performed twice using 60-day-old plants of T. tetragonioides. Unwounded roots of eight plants were dipped for 1 min in a conidial suspension (5 × 107 conidia/ml) of one isolate of V. dahliae obtained from the original infected New Zealand spinach plants, and grown in potato dextrose broth. The inoculated plants were transplanted into 2-liter pots (1 plant/pot) containing steamed potting mix (sphagnum peat-perlite-pine bark-clay; 50:20:20:10) and maintained in a growth chamber at 20 to 24°C and 50 to 80% RH. Eight plants immersed in sterile water served as a control treatment. Wilt symptoms were observed 30 days after inoculation, with vascular discoloration in the roots, crowns and stems. V. dahliae was reisolated consistently from infected tissues, but not from the control plants that remained healthy. Pathogenicity was also tested using the same method on plants of four cultivars (five plants/cultivar) of Spinacia oleracea (Matador, Asti, Merlo Nero, and America). Wilt symptoms developed on all cultivars and V. dahliae was reisolated from each inoculated plant. No fungal colonies were reisolated from control plants, which remained healthy. To our knowledge, this is the first report of Verticillium wilt caused by V. dahliae on T. tetragonioides in Italy, as well in Europe. V. dahliae was reported on T. tetragonioides in Canada (2). At this time, the economic impact of Verticillium wilt on New Zealand Spinach in Italy is limited, although the use of this vegetable in Italy is increasing. References: (1) G. F. Pegg and B. L. Brady. Verticillium Wilts. CABI Publishing, Wallingford, UK, 2002. (2) M. J. Richardson. Page 387 in: An Annotated List of Seed-Borne Diseases, Fourth Edition. International Seed Testing Association, Zurich, Switzerland, 1990. (3) T. J. White et al. Page 315 in: PCR Protocols. A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.
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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) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".