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Report of Candidatus Liberibacter caribbeanus, a new citrus- and psyllid-associated Liberibacter from Colombia, South America
M. L. KEREMANE (1), C. Ramadugu (2), A. Castaneda (3), J. E. Diaz (3), E. A. Peñaranda (3), J. Chen (4), Y. P. Duan (5), S. E. Halbert (6), R. F. Lee (7). (1) USDA ARS - Citrus Germplasm Repository, Riverside, CA, U.S.A.; (2) University of California Riverside, Riverside, CA, U.S.A.; (3) Instituto Colombiano Agropecuario, Bogota, Colombia; (4) USDA ARS, Parlier, CA, U.S.A.; (5) United States Horticultural R

We report a new species, <i>Candidatus </i>Liberibacter caribbeanus (CLca) from both the Asian citrus psyllid and <i>Citrus sinensis</i> from Cordoba in the northeastern region Colombia, South America. Additional psyllids carrying CLca were found from Barranquilla in the northern part of Colombia close to the Caribbean Sea. Quantitative real time PCR assays using primers and probes routinely used for <i>Ca</i>. L. asiaticus were capable of detecting CLca. About 5000 psyllids and 100 plant samples were tested for the presence of Liberibacter. We conducted conventional PCR and Sanger sequencing of the 16S rDNA region, followed by phylogenetic analysis, 16S metagenome analysis of the psyllid DNA, and PAC-BIO sequencing of the bacterium from psyllid. A new method, digital PCR, was utilized for sensitive detection of CLca. Confirmatory tests using multiple genomic regions of both CLca and CLas were conducted. CLca is about 92-96% similar to previously reported Liberibacters based on 16S rDNA sequence analysis. At this time, it is not clear if CLca can be cultured and if it causes HLB-like symptoms in citrus. The titer of the bacterium reaches very high levels in the psyllid. Further research to determine the pathogenicity of the organism and its role in citrus HLB is in progress.

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