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Date: May 25, 2007
Source:  Journal of Phytopathology Vol. 155, April 2007 [edited]
<http://www.blackwell-synergy.com/doi/full/10.1111/j.1439-0434.2007.01221.x>

Groundnut ringspot virus: an emerging tospovirus inducing disease in peanut crops

Diseases induced by tospoviruses cause great losses in agriculture worldwide. In Argentina, _Tomato spotted wilt virus_ (TSWV), _Groundnut ringspot virus_ (GRSV) and _Tomato chlorotic spot virus_ (TCSV) have been identified by molecular techniques as pathogens of various crops. Moreover, these viruses have been reported infecting some vegetables and ornamental plants. The occurrence of GRSV in peanut has only been reported in South Africa.

Peanut is a legume crop grown extensively in tropical and subtropical areas. In Argentina, 96 percent of peanut production is concentrated in Cordoba province. Plants showing symptoms typical of those caused by tospoviruses were observed, including stunting, smaller and distorted leaves showing severe chlorosis and concentric ringspots, which were initially thought to be caused by TSWV.

Peanut plants were collected and tested to identify the causal agent.
_Tospovirus_-like particles were observed by electron microscopy, and GRSV was identified by double antibody sandwich-enzyme-linked immunosorbent assay (DAS-ELISA) and reverse transcription-polymerase chain reaction (RT-PCR). Partial nucleotide and deduced amino acid sequences of the nucleocapsid (N) gene indicated a high degree of identity with other GRSV sequences. Thus, the virus was found to be an isolate of GRSV, named GRSV-AR. This is the 1st report of GRSV occurrence on peanuts in Argentina.

GRSV is efficiently transmitted by the thrips species _Frankliniella schultzei_ and _F. occidentalis_ and by _F. gemina_ under experimental conditions. However, in spite of the importance of the vector-virus relationship for understanding how virus spread occurs, in Argentina there is a lack of information concerning the presence and transmission efficiency of thrips vectors in peanut crops. The potential damage by tospoviruses underscores the need for epidemiological studies to understand how the virus spreads in peanut crops. Because of the worldwide distribution and emergence of tospoviruses, the identification of GRSV in the peanut-producing area of Argentina is important for future work in peanut-breeding programs.

[Byline: S. de Breuil, J. A. Abad, C. F. Nome, F. J. Giolitti, P. L. Lambertini, S. Lenardon, pp 251-254; <slenard@infovia.com.ar>]

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Communicated by:
J. Allan Dodds
Former ProMED-mail plant disease moderator <dodds@ucr.edu>

[_Groundnut ringspot tospovirus_, family _Bunyaviridae_, was 1st reported on peanuts during a survey of the viruses of this crop in South Africa in 1966. Thus far, this virus has been detected on peanuts and soybean in South Africa, where it is relatively common, and on tomatoes (and possibly solanaceous weeds) in Brazil and Argentina. It spreads in Argentina, Brazil and South Africa causing high economic losses. Apparently, this is not only the 1st report of GRSV on peanuts in Argentina but on peanuts anywhere outside South Africa.

Tospoviruses are an extremely important group of plant viruses capable of infecting a large range of important crops. The type member, _Tomato spotted wilt virus_ (TSWV), has one of the broadest host ranges among plant viruses and has had a serious impact on many crop species worldwide.

Tospoviruses are transmitted exclusively by thrips, which are found worldwide. Transmission occurs in a circulative propagative manner, meaning that the virus multiplies in the vector. Nymphs must emerge on an infected host plant to be able to acquire the virus, which is then spread by the adult insects. Thus, tospovirus epidemiology is complex. GRSV and TSWV could also be transmitted experimentally to _Arabidopsis thaliana_ (a weed species used frequently in virus
research) by mechanical inoculation.

Research on this important virus group has increased dramatically, and many new tospoviruses are being found. They often originate in developing countries, and some appear to occur only in these countries. The lack of resources in these regions may hamper the discovery of even more new tospoviruses.

Reference: Rybicki EP, Pietersen G (1999). Plant virus disease problems in the developing world. Advances in Virus Research 53: 128-175.

Map of Argentina:
<http://campus.udayton.edu/mary//resources/stamps/map%20argentina.jpg>.

Pictures:
Electron micrograph of _Tospovirus_ particles (TSWV):
<http://www.rothamsted.bbsrc.ac.uk/ppi/links/pplinks/virusems/b6.jpeg>,
Symptoms of TSWV on several vegetable species:
<http://vegetablemdonline.ppath.cornell.edu/PhotoPages/Tomatoes/Tom_SpWilt/Tom_SpWiltPhotoList.htm>,
Symptoms of TSWV on peanut seed:
<http://www.apsnet.org/education/lessonsPlantPath/TomatoSpottedWilt/text/fig06.htm>,
Western flower thrips, adult:
<http://www.insectimages.org/browse/detail.cfm?imgnum=4387048>  and  <http://insects.tamu.edu/images/insects/color/owthrip1.jpg>,
Western flower thrips, nymph and eggs:
<http://www.daylilies.org/ahs_dictionary/PestPics/thrips.gif>.

Links:
GRSV taxonomy and description:
<http://image.fs.uidaho.edu/vide/descr377.htm>,
General information on tospoviruses:
<http://www.mcb.uct.ac.za/tutorial/emerging%20plant%20viruses.htm>,
Diversity of tospoviruses in Brazil:
<http://www.apsnet.org/phyto/PDFS/1999/0628-01R.pdf>,
Mechanical inoculation of _A. thaliana_ with GRSV and TSWV:
<http://www.scielo.br/pdf/fb/v31n1/a20v31n1.pdf>,
TSWV fact sheet:
<http://vegetablemdonline.ppath.cornell.edu/factsheets/Virus_SpottedWilt.htm>,
Description of Western flower thrips vector:
<http://www.ricecrc.org/Hort/ascu/insects/wft.htm>.
- Mod.DHA]

[see also in the archive:
2002
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Groundnut ringspot virus, soybean - South Africa 20021023.5622
2001
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Tomato spotted wilt tospovirus, soybean - Iran 20011229.3130 Tomato spotted wilt, peanut - Iran 20011220.3069]

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