{{Short description|Species of bacterium}} {{italic title}} {{Automatic taxobox | image = Potato psyllid.jpg | image_caption = The potato psyllid, ''Bactericera cockerelli'', feeds on a potato and infects it with "''Candidatus'' Liberibacter solanacearum", the bacterium that causes zebra chip disease. | taxon = Liberibacter | authority = Fagen ''et al''. 2014<ref>{{cite journal |vauthors=Fagen JR, Leonard MT, Coyle JF, McCullough CM, Davis-Richardson AG, Davis MJ, Triplett EW | title = ''Liberibacter crescens'' gen. nov., sp. nov., the first cultured member of the genus ''Liberibacter'' | journal = Int J Syst Evol Microbiol | year = 2014 | volume = 64 | issue = 7 | pages = 2461–2466| doi = 10.1099/ijs.0.063255-0 | pmid = 24786353 | doi-access = free }}</ref> | subdivision_ranks = Species | subdivision = See text. | synonyms = "''Candidatus'' Liberibacter" <small>Jagoueix ''et al''. 1997</small> }}
'''''Liberibacter''''' is a genus of Gram-negative bacteria in the Rhizobiaceae family. Detection of the liberibacteria is based on PCR amplification of their 16S rRNA gene with specific primers. Members of the genus are plant pathogens mostly transmitted by psyllids. The genus was originally spelled ''Liberobacter''.<ref>{{cite web |website=National Center for Biotechnology Information |url=https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?lvl=0&id=34019 |title=Taxonomy browser 34019 }}</ref>
Most importantly, ''Liberibacter'' is a causative agent of Huanglongbing disease (HLB) also known as citrus greening disease.<ref name="Nadarasah_2011">{{cite journal | vauthors = Nadarasah G, Stavrinides J | title = Insects as alternative hosts for phytopathogenic bacteria | journal = FEMS Microbiology Reviews | volume = 35 | issue = 3 | pages = 555–75 | date = May 2011 | pmid = 21251027 | doi = 10.1111/j.1574-6976.2011.00264.x | doi-access = free }}</ref> ''Liberibacter'' is transmitted by two insects from Psyllidae family – ''Diaphorina citri'' in Asia, Brazil and Florida, and ''Trioza erytreae'' in Africa. The Asian HLB strain, "''Candidatus'' Liberibacter asiaticus" is more heat tolerant, while the African strain, ''Candidatus'' Liberibacter africanus is asymptomatic at temperatures above 30 °C.<ref name="Nadarasah_2011" /> Species of ''Liberibacter'', infecting solanaceous plants has been identified and it was carried by another psyllid, a potato pest ''Bactericera cockerelli''.<ref name="Nadarasah_2011" /><ref name = "Hansen_2008">{{cite journal | vauthors = Hansen AK, Trumble JT, Stouthamer R, Paine TD | title = A new Huanglongbing Species, "''Candidatus'' Liberibacter psyllaurous," found to infect tomato and potato, is vectored by the psyllid ''Bactericera cockerelli'' (Sulc) | journal = Applied and Environmental Microbiology | volume = 74 | issue = 18 | pages = 5862–5 | date = September 2008 | pmid = 18676707 | pmc = 2547047 | doi = 10.1128/AEM.01268-08 | bibcode = 2008ApEnM..74.5862H }}</ref>
== Genomes == The genetic diversity within the genus is best expressed as the diversity across genomes. More than 60 genomes have been sequenced, ranging in size from 233 kb to about 1.5 MB, hence the genomes are small compared to most other bacteria. The smallest genome (Candidatus ''Liberibacter asiaticus'' strain SGCA1) encodes only 655 proteins, while the largest genome (Candidatus ''Liberibacter asiaticus'' Tabriz. 3) encodes 2174 proteins.<ref>{{Cite web |title=Genome List |url=https://www.bv-brc.org/view/GenomeList/?eq(genome_id,*)&genome()#view_tab=genomes&filter=and(eq(genus,liberibacter),keyword(liberibacter)) |access-date=2023-07-31 |website=Bacterial and Viral Bioinformatics Resource Center }}</ref><ref>{{Cite web |date=2022-02-19 |title=MAG: Candidatus Liberibacter asiaticus isolate Tabriz.3, whole genome shotgun sequencing project |url=https://www.ncbi.nlm.nih.gov/nuccore/JAKQYA000000000.1 |language=en-US |website=GenBank }}</ref>
The small genome size is typical for pathogenic bacteria which often undergo genome reduction. This is due to adaptation to their host which often provides many nutrients, so that the parasite does not need genes to produce those nutrients itself.<ref>{{Cite journal |last1=Koskiniemi |first1=Sanna |last2=Sun |first2=Song |last3=Berg |first3=Otto G. |last4=Andersson |first4=Dan I. |date=June 2012 |title=Selection-driven gene loss in bacteria |journal=PLOS Genetics |volume=8 |issue=6 |article-number=e1002787 |doi=10.1371/journal.pgen.1002787 |issn=1553-7404 |pmc=3386194 |pmid=22761588 |doi-access=free }}</ref>
== Pathogenicity == ''Liberibacter'' bacteria are carried in the hemolymph and salivary glands of psyllids. Since psyllids feed on sap, this provides bacteria the entry to phloem of the plant.<ref name="Nadarasah_2011" /> They induce significant metabolic and regulatory changes that damage the plants transport system and affects plants defense systems. These impairments have downstream negative effects on citrus microbiome of the infected plants.<ref name="Wang_2017">{{cite journal | vauthors = Wang N, Stelinski LL, Pelz-Stelinski KS, Graham JH, Zhang Y | title = Tale of the Huanglongbing Disease Pyramid in the Context of the Citrus Microbiome | journal = Phytopathology | volume = 107 | issue = 4 | pages = 380–387 | date = April 2017 | pmid = 28095208 | doi = 10.1094/PHYTO-12-16-0426-RVW | doi-access = free | bibcode = 2017PhPat.107..380W }}</ref>
Since pathological ''Liberibacter'' cannot be cultivated outside of its vector or host, genetics, bacteria-vector and bacteria-plant interaction have not yet been thoroughly explored. Factors important for adaption and colonization or possible coevolution are not yet understood.<ref name="Nadarasah_2011" /><ref name="Wang_2017" /> Only in 2014 the accidental discovery of ''Liberibacter crescens'' in Babaco papaya (during a Papaya Bunchy Top Disease study), which can be cultured axenically,<ref name=":0" /> allowed researchers to establish the genus and provided a valuable model organism to study related HLB strains.
''Liberibacter'' activates salicylic acid pathway in host, likely due to recognition of extracellular molecules such as lipopolyscacharides or flagella. Pathogen in turn likely mitigates the effects, because it encodes SA hydroxylase, that degrades salicylic acid. Liberibacteria were shown to affect the spread of vector, by influencing the flight frequencies and sexual attraction of ''D. citri''. On the other hand, infection with ''Liberibacter'' causes higher mortality of ''D. citri'' adults, but not nymphs.<ref name="Wang_2017" /> ''Liberibacter'' is a part of the psyllid microbiota and co-existence with other bacteria likely has impact on the overall fitness of the insect, as well as outcome of the disease.<ref name="Wang_2017" />
== Treatment == Primary strategy for HLB disease management is a vector control. Antimicrobial treatment can suppress ''Liberibacter'' species,<ref name="johnson2020">{{cite web |last=Johnson |first=E. G. |date=February 29, 2020 |title=Zinkicide A Nanotherapeutic for HLB - University of Florida |website=National Institute of Food and Agriculture |url=https://portal.nifa.usda.gov/web/crisprojectpages/1005557-zinkicide-a-nanotherapeutic-for-hlb.html }}</ref> however usage of broad spectrum antibiotics is inadvisable due to adverse environmental effects. Alternative treatments, such as heat therapy, ''i.e.'', incubation of plant at temperatures above 40 °C for several days, show varying effects. Another suggested alternatives include the use of compounds that alleviate disease symptoms and boost plants defense systems<ref name="alferez2019">{{cite magazine |last1=Alferez |first1=Fernando |last2=Vincent |first2=Christopher |last3=Vashisth |first3=Tripti |date=June 19, 2019 |title=Update on Brassinosteroids for HLB Management |magazine=Citrus Industry Magazine |publisher=AgNet Media |location=Newberry, Florida |url=http://citrusindustry.net/2019/06/19/update-on-brassinosteroids-for-hlb-management/ }}</ref> or reinforcing natural citrus microbiota in order to compete with ''Liberibacter'' species.<ref>{{cite journal | vauthors = Blaustein RA, Lorca GL, Teplitski M | title = Challenges for Managing "''Candidatus'' Liberibacter" spp. (Huanglongbing Disease Pathogen): Current Control Measures and Future Directions | journal = Phytopathology | volume = 108 | issue = 4 | pages = 424–435 | date = April 2018 | pmid = 28990481 | doi = 10.1094/PHYTO-07-17-0260-RVW | doi-access = free | bibcode = 2018PhPat.108..424B }}</ref> Early detection of HLB positive trees and removal from the groves, and extensive control of psyllids are the crucial HLB management strategies.<ref>{{cite journal |last1=Pandey |first1=Sheo Shankar |last2=Wang |first2=Nian |title=Targeted Early Detection of Citrus Huanglongbing Causal Agent ' Candidatus Liberibacter asiaticus' Before Symptom Expression |journal=Phytopathology |date=June 2019 |volume=109 |issue=6 |pages=952–959 |doi=10.1094/PHYTO-11-18-0432-R |pmid=30667340 |doi-access=free |bibcode=2019PhPat.109..952P }}</ref><ref>{{cite journal |last1=Wang |first1=Nian |title=The Citrus Huanglongbing Crisis and Potential Solutions |journal=Molecular Plant |date=May 2019 |volume=12 |issue=5 |pages=607–609 |doi=10.1016/j.molp.2019.03.008 |pmid=30947021 |doi-access=free |bibcode=2019MPlan..12..607W }}</ref>
==Species== Named species include:<ref>{{cite web | title = ''Liberibacter'' | url = https://www.uniprot.org/taxonomy/34019 | publisher = UniProt Consortium }}</ref> * "''Ca.'' Liberibacter africanus" <small>corrig. Jagoueix ''et al''. 1994</small> originated in Africa and is a causal agent of citrus greening disease, also known as huanglongbing, and vectored by the African citrus psyllid ''Trioza erytreae''.<ref>{{cite web | title = Trioza erytreae | url = http://www.eppo.org/QUARANTINE/insects/Trioza_erytreae/TRIZER_ds.pdf | archive-url = https://web.archive.org/web/20100713203449/http://www.eppo.org/QUARANTINE/insects/Trioza_erytreae/TRIZER_ds.pdf |archive-date=2010-07-13 | work = European and Mediterranean Plant Protection Organization (EPPO) quarantine pest }}</ref> * "''Ca.'' Liberibacter americanus" <small>Teixeira ''et al''. 2005</small> is a novel species from Brazil described in 2005 and associated with huanglongbing and vectored by the Asian citrus psyllid ''Diaphorina citri''.<ref name="pmid16166678">{{cite journal | vauthors = Teixeira Ddo C, Saillard C, Eveillard S, Danet JL, da Costa PI, Ayres AJ, Bové J | title = "''Ca.'' Liberibacter americanus", associated with citrus huanglongbing (greening disease) in São Paulo State, Brazil | journal = International Journal of Systematic and Evolutionary Microbiology | volume = 55 | issue = 5 | pages = 1857–62 | date = September 2005 | pmid = 16166678 | doi = 10.1099/ijs.0.63677-0 }}</ref> * "''Ca.'' Liberibacter asiaticus" <small>corrig. Jagoueix ''et al''. 1994</small> originated in Asia and is a causal agent of huanglongbing, vectored by the Asian citrus psyllid ''D. citri''.<ref>{{cite web | title = Asian citrus psyllid | url = http://entomology.ifas.ufl.edu/creatures/citrus/acpsyllid.htm | work = Featured Creatures }}</ref> * "''Ca.'' Liberibacter brunswickensis" <small>Morris ''et al''. 2017</small><ref>{{cite journal | vauthors = Morris J, Shiller J, Mann R, Smith G, Yen A, Rodoni B | title = Novel "''Ca.'' Liberibacter" species identified in the Australian eggplant psyllid, ''Acizzia solanicola'' | journal = Microbial Biotechnology | volume = 10 | issue = 4 | pages = 833–844 | date = July 2017 | pmid = 28387006 | pmc = 5481521 | doi = 10.1111/1751-7915.12707 }}</ref> associated with the psyllid ''Acizzia solanicola'' on eggplant in Australia. * ''Liberibacter crescens'' <small>Fagen ''et al''. 2014</small><ref name=":0">{{Cite journal |last1=Fagen |first1=Jennie R. |last2=Leonard |first2=Michael T. |last3=Coyle |first3=Janelle F. |last4=McCullough |first4=Connor M. |last5=Davis-Richardson |first5=Austin G. |last6=Davis |first6=Michael J. |last7=Triplett |first7=Eric W. |date=2014 |title=Liberibactercrescens gen. nov., sp. nov., the first cultured member of the genus Liberibacter |url=https://www.microbiologyresearch.org/content/journal/ijsem/10.1099/ijs.0.063255-0 |journal=International Journal of Systematic and Evolutionary Microbiology |volume=64 |issue=Pt_7 |pages=2461–2466 |doi=10.1099/ijs.0.063255-0 |pmid=24786353 |issn=1466-5034|url-access=subscription }}</ref> was isolated from papaya growing in Puerto Rico. * "''Ca.'' Liberibacter europaeus" <small>Raddadi ''et al''. 2011</small> is a novel species described in 2010, found in pear trees, where it seems to cause no symptoms and is vectored by the psyllid, ''Cacopsylla pyri''.<ref>{{cite journal | vauthors = Raddadi N, Gonella E, Camerota C, Pizzinat A, Tedeschi R, Crotti E, Mandrioli M, Bianco PA, Daffonchio D, Alma A | title = "''Ca.'' Liberibacter europaeus" sp. nov. that is associated with and transmitted by the psyllid ''Cacopsylla pyri'' apparently behaves as an endophyte rather than a pathogen | journal = Environmental Microbiology | volume = 13 | issue = 2 | pages = 414–26 | date = February 2011 | pmid = 21040355 | doi = 10.1111/j.1462-2920.2010.02347.x | hdl = 2318/133454 | s2cid = 20625405 | hdl-access = free }}</ref> * "''Ca.'' Liberibacter solanacearum" <small>Liefting ''et al''. 2009</small><ref>{{cite journal | vauthors = Liefting LW, Weir BS, Pennycook SR, Clover GR | title = 'Candidatus Liberibacter solanacearum', associated with plants in the family Solanaceae | journal = International Journal of Systematic and Evolutionary Microbiology | volume = 59 | issue = Pt 9 | pages = 2274–6 | date = September 2009 | pmid = 19620372 | doi = 10.1099/ijs.0.007377-0 | doi-access = free }}</ref> is a causal agent of zebra chip disease in potatoes. It can also infect other economically important crops including tomatoes, carrot, parsely, parsnip, celery and chervil. There are at least ten haplotypes described within this species, designated LsoA, LsoB, LsoC, LsoD, LsoE, Lso F, LsoG, LsoH, LsoH(Con) and LsoU.<ref>{{cite journal | vauthors = Nelson WR, Sengoda VG, Alfaro-Fernandez AO, Font MI, Crosslin JM, Munyaneza JE |title= A new haplotype of "''Ca.'' Liberibacter solanacearum" identified in the Mediterranean region |doi=10.1007/s10658-012-0121-3 |volume=135 |issue= 4 |journal=European Journal of Plant Pathology |pages=633–639|year= 2012 |s2cid= 10654496 |hdl= 10251/43378 |hdl-access= free }}</ref><ref>{{cite journal |vauthors=Teresani GR, Bertolini E, Alfaro-Fernández A, Martínez C, Tanaka FA, Kitajima EW, Roselló M, Sanjuán S, Ferrándiz JC, López MM, Cambra M, Font MI |date=August 2014 |title=Association of "''Ca.'' Liberibacter solanacearum" with a vegetative disorder of celery in Spain and development of a real-time PCR method for its detection |journal=Phytopathology |volume=104 |issue=8 |pages=804–11 |doi=10.1094/PHYTO-07-13-0182-R |pmid=24502203 |doi-access=free|hdl=10251/82656 |hdl-access=free }}</ref><ref name="ReferenceA">{{Cite journal |last1=Sumner-Kalkun |first1=Jason C. |last2=Highet |first2=Fiona |last3=Arnsdorf |first3=Yvonne M. |last4=Back |first4=Emma |last5=Carnegie |first5=Mairi |last6=Madden |first6=Siobhán |last7=Carboni |first7=Silvia |last8=Billaud |first8=William |last9=Lawrence |first9=Zoë |last10=Kenyon |first10=David |date=2020-10-06 |title='Candidatus Liberibacter solanacearum' distribution and diversity in Scotland and the characterisation of novel haplotypes from Craspedolepta spp. (Psylloidea: Aphalaridae) |journal=Scientific Reports |language=en |volume=10 |issue=1 |page=16567 |doi=10.1038/s41598-020-73382-9 |issn=2045-2322|doi-access=free |pmid=33024134 |pmc=7538894 |bibcode=2020NatSR..1016567S }}</ref> Haplotypes A, B and F are associated with solanaceous plants (potatoes and tomato) and vectored by the potato tomato psyllid ''Bactericera cockerelli''.<ref>{{cite journal |last1=Crosslin |first1=James M. |last2=Munyaneza |first2=Joseph E. |date=2009 |title=Evidence that the Zebra Chip Disease and the Putative Causal Agent Can be Maintained in Potatoes by Grafting and in Vitro |journal=American Journal of Potato Research |volume=86 |issue=3 |pages=183–187 |doi=10.1007/s12230-009-9070-6 |s2cid=32565774}}</ref> Haplotypes C, D, E and H affect apiaceous crops (carrots, celery etc.). Haplotypes D and E are vectored by ''Bactericera trigonica''. Haplotype C is vectored by ''Trioza apicalis.'' The vector for haplotype H is currently unknown. Haplotype U has been found in ''Urtica dioica'' (stinging nettle) and is vectored by''Trioza urticae.''<ref name="ReferenceA"/> ** LsoA is also described as a species as "''Ca.'' Liberibacter psyllidaureus" <small>corrig. Hansen ''et al''. 2008</small><ref name = "Hansen_2008" /> or the misspelling ''Ca.'' L. psyllaurous. It is now considered synonymous as the 16S rRNA genes are identical.<ref>{{cite journal | vauthors = Nelson WR, Fisher TW, Munyaneza JE |title= Haplotypes of "''Ca.'' Liberibacter solanacearum" suggest long-standing separation |doi=10.1007/s10658-010-9737-3 |volume=130 |journal=European Journal of Plant Pathology |pages=5–12|year= 2011 |s2cid= 21470208 |url= http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=2318&context=usdaarsfacpub |url-access= subscription }}</ref> In addition to being a plant pathogen, LsoA also serves as an endosymbiont for the insect vector, by modifying tomato defenses in favor of itself and its vector.<ref name="pmid22539959">{{cite journal | vauthors = Casteel CL, Hansen AK, Walling LL, Paine TD | title = Manipulation of plant defense responses by the tomato psyllid (''Bactericerca cockerelli'') and its associated endosymbiont "''Ca.'' Liberibacter psyllaurous" | journal = PLOS ONE | volume = 7 | issue = 4 | article-number = e35191 | date = 2012 | pmid = 22539959 | pmc = 3335145 | doi = 10.1371/journal.pone.0035191 | bibcode = 2012PLoSO...735191C | doi-access = free }}</ref> * "''Ca.'' Liberibacter ctenarytainae" {{au|Thompson et al. 2017}} is vectored by ''Ctenarytaina fuchsiae''.<ref>Thompson, S., Jorgensen, N., Bulman, S., & Smith, G. A novel Candidatus Liberibacter species associated with Ctenarytaina fuchsiae, the New Zealand native fuchsia psyllid. In Science Protecting Plant Health 4187 (Brisbane; 2017).</ref> Its genome was announced under a different spelling, "''Ca.'' Liberibacter ctenarytaina".<ref>{{cite conference |conference=THE 13 TH AUSTRALASIAN PLANT VIROLOGY WORKSHOP |title=Initial analysis of the draft genome of Candidatus Liberibacter ctenarytaina |url=https://www.researchgate.net/publication/325251517 |date=February 2018}}</ref> * "''Ca.'' Liberibacter capsica" {{au|Kwak et al. 2021}} is vectoed by ''Russelliana capsici''.<ref>{{cite journal |last1=Kwak |first1=Younghwan |last2=Sun |first2=Penglin |last3=Meduri |first3=Venkata RamaSravani |last4=Percy |first4=Diana M. |last5=Mauck |first5=Kerry E. |last6=Hansen |first6=Allison K. |title=Uncovering Symbionts Across the Psyllid Tree of Life and the Discovery of a New Liberibacter Species, "Candidatus" Liberibacter capsica |journal=Frontiers in Microbiology |date=29 September 2021 |volume=12 |doi=10.3389/fmicb.2021.739763|doi-access=free |pmc=8511784 }}</ref>
== References == {{Reflist}}
== Further reading == {{refbegin}} * {{cite journal | vauthors = Kogenaru S, Yan Q, Riera N, Roper MC, Deng X, Ebert TA, Rogers M, Irey ME, Pietersen G, Rush CM, Wang N | title = Repertoire of novel sequence signatures for the detection of "''Candidatus'' Liberibacter asiaticus" by quantitative real-time PCR | journal = BMC Microbiology | volume = 14 | page = 39 | date = February 2014 | pmid = 24533511 | pmc = 4015361 | doi = 10.1186/1471-2180-14-39 | doi-access = free }} {{refend}}
== External links == * [https://gtdb.ecogenomic.org/tree?r=g__Liberibacter g__Liberibacter] in GTDB
{{Taxonbar|from=Q4262259}}
Category:Bacterial plant pathogens and diseases Category:Potato diseases Category:Rhizobiaceae Category:Candidatus taxa