Three novel lineages of 'Candidatus Liberibacter africanus' associated with native rutaceous hosts of Trioza erytreae in South Africa

dc.contributor.authorRoberts, Ronel
dc.contributor.authorSteenkamp, Emma Theodora
dc.contributor.authorPietersen, Gerhard
dc.contributor.emailgerhard.pietersen@fabi.up.ac.zaen_ZA
dc.date.accessioned2016-04-19T10:36:23Z
dc.date.available2016-04-19T10:36:23Z
dc.date.issued2015-02
dc.description.abstractGreening disease of citrus in South Africa is associated with ‘Candidatus Liberibacter africanus’ (Laf), a phloem-limited bacterium vectored by the sap-sucking insect Trioza erytreae (Triozidae). Despite the implementation of control strategies, this disease remains problematic, suggesting the existence of reservoir hosts to Laf. The current study aimed to identify such hosts. Samples from 234 trees of Clausena anisata, 289 trees of Vepris lanceolata and 231 trees of Zanthoxylum capense were collected throughout the natural distribution of these trees in South Africa. Total DNA was extracted from samples and tested for the presence of liberibacters by a generic Liberibacter TaqMan real-time PCR assay. Liberibacters present in positive samples were characterized by amplifying and sequencing rplJ, omp and 16S rRNA gene regions. The identity of tree host species from which liberibacter sequences were obtained was verified by sequencing host rbcL genes. Of the trees tested, 33 specimens of Clausena, 17 specimens of Vepris and 10 specimens of Zanthoxylum tested positive for liberibacter. None of the samples contained typical citrus-infecting Laf sequences. Phylogenetic analysis of 16S rRNA gene sequences indicated that the liberibacters obtained from Vepris and Clausena had 16S rRNA gene sequences identical to that of ‘Candidatus Liberibacter africanus subsp. capensis’ (LafC), whereas those from Zanthoxylum species grouped separately. Phylogenetic analysis of the rplJ and omp gene regions revealed unique clusters for liberibacters associated with each tree species. We propose the following names for these novel liberibacters: ‘Candidatus Liberibacter africanus subsp. clausenae’ (LafCl), ‘Candidatus Liberibacter africanus subsp. vepridis’ (LafV) and ‘Candidatus Liberibacter africanus subsp. zanthoxyli’ (LafZ). This study did not find any natural hosts of Laf associated with greening of citrus. While native citrus relatives were shown to be infected with Laf-related liberibacters, nucleotide sequence data suggest that these are not alternative sources of Laf to citrus orchards, per se.en_ZA
dc.description.departmentForestry and Agricultural Biotechnology Institute (FABI)en_ZA
dc.description.departmentMicrobiology and Plant Pathologyen_ZA
dc.description.librarianhb2016en_ZA
dc.description.sponsorshipCitrus Research International (CRI), the National Research Foundation (NRF) and the Department of Science and Technology (DST)/NRF Centre of Excellence in Tree Health Biotechnology (CTHB).en_ZA
dc.description.urihttp://ijs.sgmjournals.orgen_ZA
dc.identifier.citationRoberts, R, Steenkamp, ET & Pietersen, G 2016, 'Three novel lineages of 'Candidatus Liberibacter africanus' associated with native rutaceous hosts of Trioza erytreae in South Africa', International Journal of Systematic and Evolutionary Microbiology, vol. 65, no. 2, pp 723-731.en_ZA
dc.identifier.issn1466-5026 (print)
dc.identifier.issn1466-5034 (online)
dc.identifier.other10.1099/ijs.0.069864-0
dc.identifier.urihttp://hdl.handle.net/2263/52062
dc.language.isoenen_ZA
dc.publisherInternational Journal of Systematic and Evolutionary Microbiologyen_ZA
dc.rights© 2015 IUMS Printed in Great Britain. This is an author manuscript that has been accepted for publication in International Journal of Systematic and Evolutionary Microbiology but has not been copy-edited, formatted or proofed. Cite this article as appearing in International Journal of Systematic and Evolutionary Microbiology, vol. 65, no. 2, pp. 723-731, 2015. doi : 10.1099/ijs.0.069864-0.en_ZA
dc.subjectHorsewooden_ZA
dc.subjectWhite ironwooden_ZA
dc.subjectKnobwooden_ZA
dc.subjectLiberibacteren_ZA
dc.subjectGreeningen_ZA
dc.subjectTrioza erytreaeen_ZA
dc.titleThree novel lineages of 'Candidatus Liberibacter africanus' associated with native rutaceous hosts of Trioza erytreae in South Africaen_ZA
dc.typePostprint Articleen_ZA

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