Root rot and distortion of ginseng seedling roots caused by<i>Fusarium oxysporum</i>
Bibliographic record
Abstract
Stunted ginseng (Panax quinquefolius) seedlings with distorted roots as a result of girdling of the taproot and rotting of the root tips were observed in British Columbia and Ontario in 2005 in four fields of 1- or 2-year-old plants. Isolation from affected root tissues yielded >90% recovery of Fusarium oxysporum. Population levels of the fungus were up to 40-fold higher in the rhizosphere of affected plants compared with that of healthy plants. Inoculation of 1-year-old seedlings with four isolates of F. oxysporum under greenhouse conditions resulted in rotting of root tips, brown discolouration and death of lateral roots, followed by distortion of the taproots at a frequency of 52%-70%. DNA of F. oxysporum was detected in flowers, green berries, ripe berries, and seeds of ginseng using a DNA hybridization array. Stratified seeds showed up to an 80% incidence of F. oxysporum both in the seed coat and endosperm. Isolates of F. oxysporum from ginseng grew best under laboratory conditions at 25–30 °C and pH 5.7–6.8. Mycelial growth was significantly reduced by 10 µg/mL of the fungicides benomyl, propiconazole, fludioxonil, and thiophanate-methyl. Phylogenetic comparisons of the sequence a portion of the elongation factor-1 alpha gene grouped all 13 isolates of F. oxysporum from ginseng with 21 isolates of F. oxysporum from a range of other hosts. Inoculum of F. oxysporum originating from straw mulch or soil in ginseng gardens, together with seedborne inoculum, may be primary sources for infection of seedling roots. Key words: damping-off, molecular detection, root girdling, seedborne pathogen. En 2005, dans quatre champs de la Colombie-Britannique et de l'Ontario o[ugrave] poussaient des plants de 1 ou 2 ans, on a observé des plantules de ginseng (Panax quinquefolius) rabougries dont les racines étaient déformées à cause de la nécrose de leurs extrémités et de l'annélation du pivot. L'isolement de tissus infectés provenant de racines a révélé la présence de Fusarium oxysporum, et ce, dans des proportions dépassant les 90 %. Les taux de population de champignon enregistrés dans la rhizosphère des plants infestés étaient jusqu'à 40 fois plus élevés que chez des plants sains. L'inoculation, en serre, de plantules de un an avec quatre isolats de F. oxysporum a provoqué la nécrose des extrémités des racines, l'apparition d'une teinte brunâtre ainsi que la mort des racines secondaires, suivie de la déformation des pivots, et ce, dans une proportion variant de 52 % à 70 %. Dans les jeux d'échantillons faisant appel à l'hybridation de l'ADN, on a trouvé l'ADN de F. oxysporum sur les fleurs, les baies vertes, les baies mures et les graines du ginseng. Les graines stratifiées affichaient une incidence de F. oxysporum de près de 80 %, et sur le tégument et sur l'endosperme. Les isolats de F. oxysporum provenant du ginseng ont davantage proliféré en laboratoire quand la température variait de 25 à 30 °C et le pH, de 5,7 à 6,8. La croissance mycélienne a été inhibée de façon notable par l'utilization de 10 µg/mL de bénomyl, de propiconazole, de fludioxonil et de méthyle de thiophanate. Les comparaisons phylogénétiques d'une portion de la séquence du gène porteur du facteur d'élongation-1 alpha ont permis d'associer les 13 isolats de F. oxysporum provenant du ginseng et 21 isolats de F. oxysporum issus d'une gamme d'hôtes divers. Les inoculums provenant du paillis ou de la terre des parcelles o[ugrave] l'on cultive le ginseng, en plus des inoculums portés par les semences, semblent être les principales causes d'infection des racines des plantules. Mots-clés : fonte des semis, détection moléculaire, annélation de la racine, agent pathogène porté par les semences.
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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 | 0.000 | 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) | 0.001 | 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".