Doddapaneni, HarshavardhanLiao, HuihongLin, HongBai, XianjinZhao, XiaolongCiverolo, Edwin L.Irey, MichaelColetta-Filho, HelvecioPietersen, Gerhard2010-08-112010-08-112008-08Doddapaneni, H, Liao, H, Lin, H, Bai, X, Zhao, X, Civerolo, EL, Irey, M, Coletta-Filho, H & Pietersen, G 2008, 'Comparative phylogenomics and multi-gene cluster analyses of the Citrus Huanglongbing (HLB)-associated bacterium Candidatus Liberibacter', BMC Research Notes, vol. 1, no. 72. [www.biomedcentral.com]1756-050010.1186/1756-0500-1-72http://hdl.handle.net/2263/14617BACKGROUND: Huanglongbing (HLB, previously known as citrus greening), is associated with Candidatus Liberibacter species and is a serious threat to citrus production world-wide. The pathogen is a Gram negative, unculturable, phloem-limited bacterium with limited known genomic information. Expanding the genetic knowledge of this organism may provide better understanding of the pathogen and possibly develop effective strategies for control and management of HLB. RESULTS: Here, we report cloning and characterization of an additional 14.7 Kb of new genomic sequences from three different genomic regions of the Candidatus Liberibacter asiaticus (Las). Sequence variation analyses among the available Ca. Liberibacter species sequences as well as the newly cloned 1.5 Kb of rpoB gene from different Ca. Liberibacter strains have identified INDELs and SNPs. Phylogenetic analysis of the deduced protein sequences from the cloned regions characterizes the HLB-associated Candidatus Liberibacter as a new clade in the sub-division of the α-proteobacteria. CONCLUSION: Comparative analyses of the cloned gene regions of Candidatus Liberibacter with members of the order Rhizobiales suggest overall gene structure and order conservation, albeit with minor variations including gene decay due to the identified pseudogenes. The newly cloned gene regions contribute to our understanding of the molecular aspects of genomic evolution of Ca. Liberibacter.en© 2008 Lin et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Comparative phylogenomicsCitrus fruits -- ColoringPathogenic bacteriaGram-negative bacterial infectionsCitrus -- Diseases and pests -- ControlCitrus -- PhylogenyMicrobial genomicsMolecular cloningArticle