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Toronto, Canada

Acosta K.,Las Tunas University | Zamora L.,National Center for Animal and Plant Health | Pinol B.,National Center for Animal and Plant Health | Fernandez A.,Las Tunas University | And 6 more authors.
Crop Protection | Year: 2013

Two different papaya diseases have been previously reported in Cuba, Bunchy Top Symptom (BTS) associated with a phytoplasma of group 16SrII '. Candidatus Phytoplasma aurantifolia' and Papaya Bunchy Top (PBT), associated with a rickettsia. Regarding the regional phytosanitary impact of both diseases for the papaya crop, the present study investigated the occurrence of BTS and PBT in papaya fields in Cuba, and the possible mixed infection of phytoplasma and rickettsia pathogens associated. Papaya plants showing symptoms of BTS or PBT or both, were collected in Las Tunas and Havana provinces from January 2009 to February 2010, and evaluated for phytoplasma and rickettsia by PCR with primers targeting the 16S ribosomal RNA and the rickettsial succinate deshydrogenase (sdhA) genes, respectively. Phytoplasmas and rickettsia were individually detected in 76/86 BTS-symptomatic and 22/22 PBT-symptomatic papaya plants, and simultaneously detected in 5/86 (5.81%) of the BTS-symptomatic and 17/22 (77.27%) of the PBT-symptomatic plants. Conventional and virtual RFLP analyses of the 16S rDNA sequences revealed the presence of phytoplasmas of group 16SrI '. Candidatus Phytoplasma asteris' and 16SrII in papaya plants affected by BTS and PBT, and identified two new phytoplasma subgroups, 16SrI-X and 16SrII-N in papayas fields of Las Tunas, which was confirmed by phylogenetic analysis. The partial rickettsia sdhA gene sequences were 100% identical to that of the rickettsia associated with PBT in Puerto Rico. Results confirm that phytoplasmas are consistently associated with both BTS and PBT symptoms, and that mixed infections of phytoplasma and rickettsia pathogens can occur in either BTS or PBT-affected papaya fields, which implies new epidemiological constraints for the disease control. © 2012 Elsevier Ltd. Source


Arocha-Rosete Y.,Sporometrics | Kent P.,Agriculture and Agri Food Canada | Agrawal V.,Sporometrics | Hunt D.,Agriculture and Agri Food Canada | And 6 more authors.
Canadian Journal of Plant Pathology | Year: 2011

Prunus and Pyrus species affected with phytoplasma diseases, as well as leafhopper species collected from Prunus and Pyrus fields in Ontario, Canada were tested for presence of phytoplasmas. Preliminary results showed that Graminella nigrifrons is a potential vector for phytoplasma groups 16SrI-W (Candidatus Phytoplasma asteris), and 16SrVII-A (Candidatus Phytoplasma fraxini) to a variety of plant hosts, including peach, apricot, plum and pear. Results showed that G. nigrifrons may be able to transmit both phytoplasma groups simultaneously within the same location and suggest that G. nigrifrons populations appear to have a complex ecology. © 2011 The Canadian Phytopathological Society. Source


Arocha-Rosete Y.,Sporometrics | Arocha-Rosete Y.,University of Windsor | Zunnoon-Khan S.,Greenhouse and Processing Crops Research Center | Krukovets I.,Greenhouse and Processing Crops Research Center | And 6 more authors.
Canadian Journal of Plant Pathology | Year: 2011

Peach trees exhibiting peach rosette-like disease symptoms and infected by a phytoplasma of group 16SrI 'Candidatus Phytoplasma asteris' at the Canadian Clonal Genebank were further tested for the pathogen characterization based on the 16S rRNA gene. Nested PCR with phytoplasma universal primers R16mF2/R1 and R16F2n/R2 resulted in amplification of products of approximately 1.25 kb from all four symptomatic trees tested. Virtual RFLP of the R16F2n/R2 sequenced amplicons with selected restriction endonucleases showed unique RFLP patterns when compared to the described 16SrI phytoplasma subgroups; these data were confirmed by phylogenetic analyses. The phytoplasma was therefore assigned as a member of a new 16SrI subgroup (16SrI-W). Results represent the first report of a new phytoplasma 16SrI subgroup infecting peach in Canada, and provide a valuable tool for further epidemiological studies on this phytoplasma in peach. © 2011 The Canadian Phytopathological Society. Source


Arocha-Rosete Y.,Sporometrics | Konan Konan J.L.,DeLorme | Diallo A.H.,Nangui Abrogoua University | Allou K.,DeLorme | And 2 more authors.
Canadian Journal of Plant Pathology | Year: 2014

Coconut palms from the Grand-Lahou region of Co'Ivoire exhibiting lethal yellowing-like symptoms and infected by a phytoplasma were further tested for the characterization of the phytoplasma pathogen based on the 16S rRNA gene analysis. Nested PCR with phytoplasma universal and lethal yellowing-specific primers resulted in amplification of products of expected sizes from seven out of 17 symptomatic trees tested, while non-infected symptomless plants yielded no DNA amplification. The 16S rDNA sequence of the phytoplasma detected from Grand-Lahou in coconut trees (KC999037) affected with the Co'Ivoire Lethal Yellowing disease showed a 99% sequence identity with that of the Ghanaian lethal yellowing phytoplasma (Cape St. Paul Wilt strain) of group 16SrXXII. The 16S rDNA sequence-based virtual and actual RFLP and phylogenetic analyses revealed that the phytoplasma associated with Co'Ivoire Lethal Yellowing in Grand Lahou is as a member of a new subgroup within group 16SrXXII that was designated as 16SrXXII-B. The present results support previous suspicions of disease spread to Co'Ivoire from neighbouring Ghana, posing a threat to the survival of the coconut trees in the Grand-Lahou region and for the Ivorian coconut industry. © 2014 The Canadian Phytopathological Society. Source


Rosete Y.A.,Sporometrics | Diallo H.A.T.T.A.,Nangui Abrogoua University | Konan Konan J.L.,Center National Of Recherche Agronomique Cnra | Kouame A.E.P.,Nangui Abrogoua University | And 20 more authors.
Canadian Journal of Plant Pathology | Year: 2016

Coconut farms located in the southern coast of Grand-Lahou in Côte d’Ivoire are severely affected by a lethal yellowing disease (CILY) associated with the group 16SrXXII-B, ‘Candidatus Phytoplasma palmicola’-related strains. Given the high prevalence of weed species on most of the farms, plants growing within and in the periphery of five selected coconut farms were assessed for the presence of the CILY phytoplasma to identify potential alternative hosts. A total of 396 plant samples belonging to 84 plant species and 35 botanical families were collected. Total DNA was extracted and tested by nested PCR with primers targeting the 16S rRNA and the translocation protein (secA) phytoplasma genes, and sequenced. Twenty samples from six plant species and five botanical families yielded PCR amplicons of the expected size, and both the secA and 16S rDNA sequences showed over 99% similarity with that of the Côte d’Ivoire lethal yellowing phytoplasma previously identified from coconut palms grown in Grand-Lahou coconut farms. Plant species from the families Poaceae (Paspalum vaginatum, Pennisetum pedicillatum), Verbenaceae (Stachytarpheta indica), Plantaginaceae (Scoparia dulcis), Phyllanthaceae (Phyllantus muellerianus) and Cyperacea (Diplacrum capitatum) were positive for the presence of the CILY phytoplasma, suggesting they may have epidemiological implications for disease spread in coconut farms in Grand-Lahou. © 2016 The Canadian Phytopathological Society. Source

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