First Report of Quinoa Downy Mildew Caused by <i>Peronospora variabilis</i> in Republic of Korea
Notice bibliographique
Résumé
Quinoa (Chenopodium quinoa Willd.) has become increasingly popular due to its high nutritional value and adaptability to harsh environments. Several field trials have recently been conducted to determine the ability of quinoa cultivars to grow under climate and soil conditions of Republic of Korea. During July 2013, which is the rainy season, plants showing typical symptoms of downy mildew were first observed in an experimental plot in Iksan City, Korea. Infection resulted in small to large, irregular chlorotic areas on the upper leaf surface with a gray mildew developing on the abaxial surface, and often leading to early defoliation. The same symptoms of downy mildew were also found in Pyeongchang County and Imsil County, Korea. A sample from Iksan City was deposited in the Korea University Herbarium (Accession No. KUS-F27388) and used for microscopy and molecular studies. Microscopic examination revealed colorless conidiophores emerging from stomata, straight to slightly curved, 350 to 550 × 10 to 18 μm, and sub-dichotomously branched in 5 to 7 orders. Ultimate branchlets were mostly in pairs, flexuous to curved, 10 to 30 μm long, and had obtuse tips. Conidia were pale brown to olivaceous, broadly ellipsoidal to ellipsoidal, and 25 to 32 × 22 to 25 μm with a length/width ratio of 1.20 to 1.35. These characteristics fit well with Peronospora variabilis, which was previously recorded to be parasitic to C. quinoa and C. album, although P. farinosa f. sp. chenopodii has often been considered a causal agent of downy mildew on quinoa (1). To confirm this morphological identification, amplification and sequencing of the internal transcribed spacer (ITS) region of the rDNA of the Korean specimen were performed using procedures outlined by Choi et al. (1) with oomycete-specific primers DC6 and LR0. The resulting 796-bp sequence was deposited in GenBank (Accession No. KF887493). A comparison with the ITS sequences available in GenBank revealed that it is identical to P. variabilis found on C. album (EF614959, EF614961), and shows only one base pair substitution with another isolates from C. quinoa (EU113305, EU113306). Therefore, the pathogen found in Korea was confirmed to be P. variabilis. Downy mildew is the most damaging disease of quinoa in Argentina, Bolivia, Colombia, Ecuador, and Peru (1). Increasing reports of this disease from India, Canada, the United States, Portugal, and Denmark (2,3,4) have revealed its worldwide occurrence and spread. To our knowledge, this is the first report of a downy mildew on quinoa in Korea (3). It suggests that quinoa downy mildew poses a new and serious threat to production of this crop in Korea. References: (1) Y. J. Choi et al. Mycopathologia 169:403, 2010. (2) S. Danielson et al. Seed Sci. Technol. 32:91, 2004. (3) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., Online publication, ARS, USDA, Retrieved November 5, 2013. (4) A. L. Testen et al. Plant Dis. 96:146, 2012.
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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 ».