ARS | Publication request: Comparison of “Candidatus Liberibacter asiaticus” populations from Brazil, China, and U. S. at two non-related genomic loci

Submitted to: American Phytopathological Society
Publication Type: Abstract Only
Publication Acceptance Date: May 20, 2011
Publication Date: June 24, 2011
Citation: Deng, X., Chen, J., Lopez, S., Wang, X., Sun, X., Jones, D., Irey, M., Civerolo, E.L. 2011. Comparison of “Candidatus Liberibacter asiaticus” populations from Brazil, China, and U. S. at two non-related genomic loci. Phytopathology. 101:S41.

Technical Abstract: Huanglongbing (HLB, yellow shoot disease) is a highly destructive disease affecting citrus production worldwide. “Candidatus Liberibacter asiaticus” is associated with HLB. Information about population diversity of “Ca. L. asiaticus” from different geographical regions is important for HLB epidemiological research and disease control. In this study, DNA samples of “Ca. L. asiaticus” from Brazil, China, and U. S. were collected. Variation among bacterial populations was evaluated using sequences at two non-related genomic loci, CLIBASIA_01645 and CLIBASIA_05610. The former has a hyper-variable region with different tandem repeat numbers (TRNs) and the latter has single nucleotide polymorphisms (SNPs). At the CLIBASIA_01645 locus, the Brazil population is predominated by TRN>10 strain, contrasting to the U. S. population with TRN<10 strains being predominant and the China population with highly heterogeneous TRN genotypes, as previously reported (Phytopathology 100:567-572). At the CLIBASIA_05610 locus, all studied China strains, Brazil strains and the TRN>10 U. S. strains were identical, whereas the TRN<10 U. S. strains have unique substitution at 9 positions. By combining the results from these two different molecular markers, it is concluded that 1) China and U. S. populations of “Ca. L. asiaticus” are distinct; 2) Florida has two different “Ca. L. asiaticus” populations; and 3) the Brazil population of “Ca. L. asiaticus” was unique and highly homogeneous.