First Report of Downy Mildew Caused by <i>Peronospora arthurii</i> on Common Evening Primrose (<i>Oenothera biennis</i>) in Italy
Notice bibliographique
Résumé
Common evening primrose (Oenothera biennis L.) belonging to the family Onagraceae is a low-maintenance biennial plant that is widely used as a border for blooming in the late spring and summer in parks and gardens in northern Italy. During spring 2017, symptoms of a downy mildew were observed on about 400 plants of O. biennis growing in mixed borders as well as in pots, in a private garden near the city of Biella (northern Italy). Plants were originated by seeds produced in Italy, and they were reproduced spontaneously in this garden for about 10 years. Infected leaves showed yellow, vein-limited lesions on the upper surface. As the disease progressed, affected leaves turned necrotic, and plants lost their aesthetic value. The abaxial surface of affected leaves was covered by gray conidiophores and conidia in areas delimited by veins. Conidiophores measured 218 to 374 μm (average, 295 μm). Conidiophores branched dichotomously four to six times with terminal branches arranged at right angles and with curved ultimate branchlets that measured 7.6 to 20.2 μm (average 12.8 μm). Conidia were light gray, elliptic to ovoid, and measured 21.1 to 27.4 × 16.1 to 20.2 μm (average, 24.4 × 18.1 μm). These morphological characteristics corresponded to those described by Mułenko and Gosztyła (1997) for Peronospora arthurii. The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS1/ITS4 (White et al. 1990) and sequenced. BLAST analysis (Altschul et al. 1997) of a 730-bp sequence (GenBank accession no. MF370230) revealed 99% similarity to that of P. arthurii AY198284. Pathogenicity was confirmed by gently pressing affected leaves of O. biennis with conidia of P. arthurii onto moistened leaves of three 4-month-old healthy plants of the same host. Nine affected leaves (three for each inoculated plant) were used. Leaves of three control plants were moistened with sterilized water. All plants were kept in a humid chamber located outside, at temperatures ranging from 9 to 27°C (17 h daylight, 7 h dark) for 7 days. First yellowing appeared after 10 days only on inoculated plants. As the disease progressed, the same conidiophores and conidia described above were observed on affected leaves. P. arthurii on O. biennis has been reported in Austria, Canada, the Czech Republic, the United States (Farr and Rossman 2017), and Poland (Mułenko and Gosztyła 1997). This is the first report of P. arthurii on O. biennis in Italy. The economic importance of this disease is at present limited, although it could spread owing to the increased planting of O. biennis in low-maintenance gardens.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».