First Report of a 16Sr I-B Phytoplasma Associated with Phyllody and Stem Fasciation of Flax (<i>Linum usitatissimum</i>) in India
Notice bibliographique
Résumé
Flax or linseed is grown as a fiber or oilseed crop in tropical and temperate regions. It is commercially cultivated in many countries of the world including Canada, China, India, the United States, Ethiopia, Pakistan, Russia, Poland, and Argentina (1). In December 2013, symptoms suggestive of phytoplasma infection were noticed on flax in different experimental fields of Central Research Institute for Jute and Allied Fibres (CRIJAF) research farm, Barrackpore, India, and the incidence was less than 2%. Because incidence of phytoplasma diseases are increasing worldwide, occurrence of a phytoplasma in a new geographical area poses an imminent threat. The infected plants showed floral virescence, phyllody, and stem fasciation (flattened stem). Floral malformation was very conspicuous with abnormal structures replacing normal flowers. All the floral parts, including petals, turned into green leaves. Total DNA was extracted from leaf mid veins of three symptomatic and three asymptomatic plants using a DNeasy Plant Mini Kit (Qiagen). PCR was carried out with the phytoplasma-specific universal P1/P7 primer set followed by nested primer pair R16F2n/R16R2 (2), resulting in DNA amplicons that were 1.8 kb and 1.2 kb, respectively, in all symptomatic samples tested. No amplification was observed with DNA from symptomless samples. This suggested association of a phytoplasma with the disease. The five purified nested PCR products were cloned in a pGEM-T Easy vector (Promega) and sequenced. One of the sequences that proved to be identical to the others was deposited in GenBank (Accession No. KJ417660). The consensus sequence was analyzed by NCBI BLAST and found to share 99% similarity with the 16Sr DNA sequence of the 'Candidatus Phytoplasma asteris' reference strain (GenBank HQ828108), which belongs to 16SrI group. The phylogenetic tree based on 16SrDNA sequence of phytoplasmas belonging to group 16SrI and other distinct phytoplasma groups also showed that the phytoplasma clustered with members of group 16SrI (3). The nested PCR product of R16F2n/R16R2 was digested using restriction enzymes AluI, BfaI, BstU, HhaI, HpaI, KpnI, MseI, and RsaI. The RFLP patterns were compared with those of known phytoplasma strains (2) and they matched the patterns for aster yellows subgroup B (16Sr I-B). Subsequently, the iPhyClassifier 16Sr group/subgroup classification based on similarity (4) analyses showed that the studied strain had 16SrDNA sequences in the 16SrI-B group with a similarity coefficient of 1.00. To the best of our knowledge, this is the first report of 16SrI-B phytoplasma associated with flax in India. References: (1) K. P. Akhtar et al. Phytoparasitica 41:383, 2013. (2) I. M. Lee et al. Int. J. Syst. Evol. Microbiol. 54:337, 2004. (3) N. Saitou and M. Nei. Mol. Biol. Evol. 4:406, 1987. (4) Y. Zhao et al. Int. J. Syst. Evol. Microbiol. 59:2582, 2009.
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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 ».