A ProMED-mail post <http://www.promedmail.org>
ProMED-mail is a program of the International Society for Infectious Diseases <http://www.isid.org>
Date: March 2017
Source: European Plant Protection Organisation (EPPO) Reporting Service 2/2017/065 [edited] <http://archives.eppo.int/EPPOReporting/2017/Rse-1703.pdf>
1st reports of a new bacterial leaf blight of rice caused by _Pantoea ananatis_ and _stewartii_
In Benin, surveys were carried out in rice to assess the importance of bacterial leaf blight caused by _Xanthomonas oryzae_ pv. _oryzae_ (EPPO A1 List). Symptomatic leaf samples gave negative results in a multiplex PCR test for _X. oryzae_. Further studies revealed bacteria belonging to the genus _Pantoea_. Molecular and pathogenicity tests confirmed _P. ananatis_ and _P. stewartii_ (EPPO A2 List). Symptoms were observed in all 14 surveyed sites with a disease incidence from 30 to 100 per cent.
In Togo, surveys were carried out to evaluate the prevalence of plant-pathogenic bacteria. [In] rice showing characteristic symptoms of bacterial leaf blight, similarly, the bacteria isolated from leaves and grains were shown to be _P. ananatis_ and _P. stewartii_.
This is the 1st time that _P. ananatis_ and _P. stewartii_ are found causing a leaf blight disease on rice in Benin and Togo. According to the EPPO Secretariat this is also the first time that _P. stewartii_ is reported from Africa.
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communicated by: ProMED-mail <promed@promedmail.org>
[The genus _Pantoea_ belongs to the family of _Enterobacteriaceae_, which also comprises genera pathogenic to humans or animals. However, the majority of its members are plant-associated. Species in the genus can affect a number of crops. For example, _P. stewartii_ causes Stewart's bacterial wilt on maize, an important insectborne disease in parts of the USA and Europe; a new disease on maize, brown stalk rot, was reported to be caused by _P. ananatis_ and an undescribed novel _Pantoea_ species; _P. citrea_ is the causal agent of pink disease of pineapple; center rot of onion is caused by _P. ananatis_; a bacterial blight of _Eucalyptus_ and a leaf blotch disease of sudangrass have also been associated with _Pantoea_ species; _P. agglomerans_ is associated with leaf blights of cereals, including rice. The effects of different bacterial strains on hosts can vary dramatically. The bacteria are generally transmitted by insect vectors, plant material and infected seed, making them a quarantine risk.
In rice, _P. ananatis_ leaf blight symptoms may include lesions on stems, stem necrosis, and leaf blight. The pathogen has also been reported to cause sheath and grain rot, as well as kernel discolouration. _P. stewartii_ has previously been isolated from seeds, but the report above appears to be the first time it has been associated with a leaf blight of the crop. Both species are considered emerging rice pathogens.
Maps
Togo:
<http://www.lonelyplanet.com/maps/africa/togo/map_of_togo.jpg> and <http://healthmap.org/promed/p/64>
Benin:
<http://www.lonelyplanet.com/maps/africa/benin/map_of_benin.jpg> and <http://healthmap.org/promed/p/59>
Africa, overview:
<http://www.worldatlas.com/webimage/countrys/africa/maps/africa.jpg>
Pictures
_P. ananatis_ symptoms on rice:
<http://www.publish.csiro.au/temp/AP04053_F1.gif>
_Xanthomonas_ leaf blight of rice:
<http://www.knowledgebank.irri.org/images/stories/bacterial-leaf-blight-4.JPG>,
<https://bugwoodcloud.org/images/768x512/0162037.jpg>, and <http://www.apsnet.org/edcenter/advanced/topics/EcologyAndEpidemiologyInR/ModelingDispersalGradients/PublishingImages/BacterialBlight.jpg>
Links
_P. ananatis_ on rice:
<http://www.publish.csiro.au/ap/Fulltext/ap04053>,
<http://www.apsnet.org/publications/plantdisease/2011/December/Pages/95_12_1582.2.aspx>,
<http://apsjournals.apsnet.org/doi/10.1094/PDIS-94-4-0482B>,
<https://www.ndrs.org.uk/article.php?id=032021>, and via <http://pbt.padil.gov.au/pbt/index.php?q=node/15&pbtID=173>
_P. stewartii_ from rice seeds:
<https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4707233/> and <http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2672.2009.04268.x/full>
Information on _P. stewartii_, incl. host list:
<http://www.plantwise.org/KnowledgeBank/Datasheet.aspx?dsid=21939>
_Xanthomonas_ leaf blight of rice, disease information:
<http://www.knowledgebank.irri.org/decision-tools/rice-doctor/rice-doctor-fact-sheets/item/bacterial-blight>,
and
<http://www.cabi.org/isc/datasheet/56956>
Description of genus _Pantoea_:
<http://www.tgw1916.net/Enterobacteria/Pantoea.html>
Information on _Pantoea_ species and subspecies:
<http://www.bacterio.net/pantoea.html> and <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2643697/>
Genus _Pantoea_ taxonomy and species:
<http://www.uniprot.org/taxonomy/53335>
EPPO alert lists via:
<https://www.eppo.int/QUARANTINE/quarantine.htm>
- Mod.DHA]
[See Also:
2016
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Pantoea, papaya - Australia: new subspecies (WA)
http://promedmail.org/post/20160104.3911037
2013
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Stewart's wilt, maize - Argentina: 1st rep (CB)
http://promedmail.org/post/20130603.1752215
2008
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P. agglomerans, cereals - Mexico: 1st rep
http://promedmail.org/post/20080111.0140
and additional items on _Xanthomonas_ leaf blight in the archives]