A ProMED-mail post
<http://www.promedmail.org>
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International Society for Infectious Diseases <http://www.isid.org>
Date: Thu 28 Jun 2012
Source: EON (Enhanced Online News) [edited] <http://eon.businesswire.com/news/eon/20120628005365/en/potato-virus-Y/PVY/fungicide>
Bacillus mycoides J emergency exemption for seed potatoes
The re-emergence of _Potato Virus Y_ (PVY) [ProMED-mail post 20110128.0331] in potato seed stock is of great concern to farmers because insecticides used to control the aphids that vector PVY do not effectively decrease transmission of the disease.
In response, the US EPA [Environmental Protection Agency] has granted an Emergency Exemption to the Montana Department of Agriculture for use of BmJ to control PVY on up to 2675 acres [1083 ha] of seed potatoes. Manufactured by Certis USA, BmJ contains _Bacillus mycoides_ isolate J, a bacterium discovered by Montana State University [MSU] that has been shown to trigger a plant's immune response to pathogenic fungi, bacteria, and viruses. Products that can produce this response (called systemic acquired resistance) represent an advancement in the management of pests and plant diseases.
MSU's Barry Jacobsen and his colleagues discovered and patented BmJ, which is a naturally occurring bacterium. BmJ, they found, "turns on"
specific genes found in most plants. These genes induce the plant to produce defensive reactions that make it more difficult for a pathogen, such as PVY, to infect the plant. BmJ is a resistance activator with no direct effect on the plant pathogen itself. That characteristic makes BmJ a potentially valuable tool for use in fungicide resistance management programs.
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[_Potato Virus Y_ (PVY; type member of genus _Potyvirus_) is one of the most damaging potato viruses affecting crop yields and tuber quality. PVY can also affect tomato, capsicum, and some other related species. Symptoms vary depending on viral strains and susceptibility level of host cultivar. They may include mottling, distortion and necrosis of leaves and stems, premature defoliation, tuber necrosis and plant death, or no symptoms at all.
PVY is transmitted by aphids in a non-persistent manner, with _Myzus persicae_ being the most efficient vector. PVY can also be spread by mechanical means, plant-to-plant contact, or with infected planting material such as seed tubers. Disease management of PVY and other potato viruses relies largely on clean planting material and use of resistant crop varieties, but reduction of available virus reservoirs and vector numbers may also be useful.
The emergence of new PVY strains has recently been reported from different areas, including an increase in new tuber-necrotic strains in the US (ProMED-mail post 20110128.0331). Numbers of co-infecting strains will build up with every crop cycle if PVY infected seed tubers are used, especially if these are moved to different areas where the virus strains they carry may combine with local PVY populations.
Induced (or acquired) systemic resistance (ISR) of plants against pathogens is a widespread phenomenon. It is a host response triggered by a local infection that leads to long lasting disease resistance effective against fungi, bacteria, and viruses. Changes in cell walls, pathogenesis related enzyme modifications and/or production of phytoalexins have been found to be associated, but further defensive compounds are likely to exist.
_Bacillus mycoides_ is a common, ubiquitous soil bacterium assigned to the _B. cereus_ species complex. Strain J, a non-pathogenic, phyllosphere inhabiting isolate, was previously shown to be effective as a biocontrol agent against the fungal cercospora leaf spot (_Cercospora beticola_) of sugar beet reducing disease incidence by up to 90 per cent in both glasshouse and field experiments (see link below).
Maps
USA:
<http://www.mapsofworld.com/usa/usa-state-and-capital-map.html> and <http://healthmap.org/r/1hiS> Individual states via:
<http://www.mapsofworld.com/usa/states/>
Pictures
PVY symptoms on potato:
<http://www.inra.fr/hyp3/images/6034404.jpg> (leaves), <http://www.umext.maine.edu/images/PVY.jpg> (leaves), <http://www.inra.fr/hyp3/images/6034401.jpg> (plant), and <http://images.photoresearchers.com/photos/preview/bn/bn3297.jpg>
(tubers)
Symptoms of different PVY strains:
<http://www.virologyj.com/content/figures/1743-422X-8-207-1.jpg> and <http://ars.els-cdn.com/content/image/1-s2.0-S016817020900104X-gr1.jpg>
PVY particles, electron micrograph:
<http://www.ppi-bg.org/i/sn5.jpg>
Aphid vector _Myzus persicae_:
<http://bit.ly/NnIFsS>
_B. mycoides_ colonies:
<http://www.biomedcentral.com/content/figures/1471-2180-2-33-1.jpg>
Links
Information on _Potato virus Y_:
<http://www.inra.fr/hyp3/pathogene/6potviy.htm>,
<http://nu-distance.unl.edu/homer/disease/agron/Potato/PoViY.html>,
<http://www.dpvweb.net/dpv/showdpv.php?dpvno=242>, and <http://ictvdb.bio-mirror.cn/ICTVdB/00.057.0.01.001.htm>
Information on PVY and other potato viruses:
<http://extension.umaine.edu/publications/2492e/> and <http://vegetablemdonline.ppath.cornell.edu/factsheets/Virus_Potato.htm>
Review and diagnosis of PVY strains:
<http://www.virologyj.com/content/6/1/48>
PVY taxonomy via:
<http://ictvonline.org/virusTaxonomy.asp?version=2011>
_B. mycoides_ strain J biopesticide fact sheet:
<http://www.epa.gov/oppbppd1/biopesticides/ingredients/factsheets/factsheet_006516.htm>
_B. m._ strain J induced fungal resistance:
<http://www.sciencedirect.com/science/article/pii/S0885576503904437>
_B. mycoides_ taxonomy:
<http://www.uniprot.org/taxonomy/1405>
Background information on induced systemic resistance:
<http://aob.oxfordjournals.org/content/89/5/503.full>
Certis biopesticides:
<http://www.certisusa.com>. - Mod.DHA]
[see also:
2011
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Potato virus Y - USA: new strains 20110128.0331
2010
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Potato virus Y - Australia: update 20100329.0984 Potato viruses - Canada: (PE) 20100125.0273
2009
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Potato virus Y - South Africa: new strain, spread 20091111.3913 Potato virus Y - Switzerland: new strains 20090703.2396 Viruses & nematodes, potato - UK: alert 20090212.0628
2002
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Potato virus Y, necrotic strain - USA (north west) 20021001.5434
1997
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Potato viruses - Saudi Arabia 19970414.0796 Aphis gossypii: new potato virus vector? - UK 19970113.0059]
Species
