Submitted to: Genome Announcements
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/19/2013
Publication Date: 5/23/2013
Citation: Lin, H., Coletta-Filho, H.D., Han, C.S., Lou, B., Civerolo, E.L., Machado, M.A., Gupta, G. 2013. Draft genome sequence of “Candidatus Liberibacter americanus” bacterium associated with citrus huanglongbing in Brazil. Genome Announcements. 1(3):e00275.13. Interpretive Summary: ‘Candidatus Liberibacter americanus’ (Lam) is a bacterium that causes citrus huanglongbing (HLB) in Brazil. As pure cultures of the bacterium are not available, information regarding genetic and pathogenic aspects of Lam is limited. To obtain genetic information, a draft genome DNA sequence of a Lam strain from São Paulo, Brazil was obtained by using next generation sequencing technology. Comparative genome analyses of Lam and other Liberibacter bacteria species were performed, advancing the understanding of the potential of Lam to cause disease. Information derived from this study will facilitate development of effective strategies for controlling HLB disease.
Technical Abstract: The genus of‘Candidatus Liberibacter’ belongs to Gram-negative, a-proteobacteria. There are four pathogenic Liberibacter species in this genus, ‘Candidatus Liberibacter asiaticus’ (Las), ‘Candidatus Liberibacter africanus’ (Laf) and ‘Candidatus Liberibacter americanus’ (Lam), which are associated with citrus huanglongbing (HLB), and ‘Candidatus Liberibacter solanacearum’ (Lso) which is associated with potato zebra chip disease and other diseases of solanaceous crops. To gain insight into the bacterial genomic information, the draft genome of Lam strain PW_SP from São Paulo, Brazil was obtained using Illumina HiSeq 2000. The Lam genome comprises 1,176,071 nucleotides with GC content of 31.6 %. The genome contains 948 coding proteins, 38 tRNAs, 3 complete copies of ribosomal RNA genes (16S, 23S and 5S) and 213 hypothetical genes. While Lam is associated with citrus HLB, comparative genome analyses of the Las, Lso and Lam genomes indicated that the Lam genome was more similar to Lso than to Las with respect to genomic structure and sequence similarity. Phylogenetic analysis using 52 orthologous genes from pathogenic liberibacter Las, Lso and Lam along with the members of Rhizobiaceae and other a-proteobacteria shows that Lam is closely positioned proximal to the basal node, followed by Lso and Las, indicating early divergence of Lam. This Lam genome sequence extends comparative genome analyses, and advances the understanding of reductive genome evolution in liberibacter.