April 7, 2006
From: ProMED-mail<promed@promedmail.org>
Source: American Phytopathological Society, Plant Disease Notes, April 2006 [edited] <http://www.apsnet.org/pd/searchnotes/2006/PD-90-0526A.asp>


First report of cucurbit aphid-borne yellows virus in Iran causing yellows on four cucurbit crops
K. Bananej, Plant Virus Research Department, Plant Pests and Diseases Research Institute (PPDRI), P.O. Box-19395-1454, Tehran, Iran; C. Desbiez and C. Wipf-Scheibel, INRA, Station de Pathologie Vegetale, Domaine St Maurice, BP94, 84143, Montfavet cedex, France; I. Vahdat, Plant Virus Research Department, Plant Pests and Diseases Research Institute (PPDRI), P.O. Box-19395-1454, Tehran, Iran; A. Kheyr-Pour, Institute des Sciences Vegetales, CNRS, 91198 Gif Sur Yvette Cedex, France; A. Ahoonmanesh, Department of Plant Protection, College of Agriculture, Esfahan University of Technology, Esfahan, Iran; and H. Lecoq, INRA, Station de Pathologie Vegetale, Domaine St Maurice, BP94, 84143, Montfavet cedex, France. Plant Dis. 90:526, 2006; published on-line as DOI: 10.1094/PD-90-0526A. Accepted for publication 26 Jan 2006.

A survey was conducted from 2001 to 2004 in the major cucurbit-growing areas in Iran to reassess the relative incidence of cucurbit viruses. Severe yellowing symptoms were observed frequently on older leaves of cucurbit plants in various regions in outdoor crops, suggesting the presence of Cucurbit aphid-borne yellows virus (CABYV, genus Polerovirus, family Luteoviridae) (1,2). Leaf samples (n = 1019) were collected from plants of melon (_Cucumis melo_ L.), cucumber (_C. sativus_ L.), squash (_Cucurbita_ sp.), and watermelon (_Citrullus lanatus_ L.) showing various virus-like symptoms (mosaic, leaf deformation, yellowing). All samples, collected from 15 provinces, were screened for the presence of CABYV by double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) with IgGs and alkaline phosphatase-conjugated IgGs against a CABYV reference isolate (1). Of the 1019 samples tested, 471 were positive for CABYV using DAS-ELISA. Some of the positive samples had typical severe yellowing symptoms while symptoms in other samples were masked by mosaic or leaf deformations caused by other viruses frequently found in mixed infections  (data not shown). During the entire survey, CABYV was detected by DAS-ELISA in 201 of 503 melon samples, 72 of 129 cucumber samples, 158 of 249 squash samples, and 40 of 138 watermelon samples. These results indicate that CABYV is widely distributed on 4 cucurbit species in the major growing areas of Iran. In order to confirm CABYV identification, total RNA extracts (TRI-Reagent, Sigma Chemical, St Louis, MO) were obtained from 25 samples that were positive using DAS-ELISA originating from Khorasan (n = 4), Esfahan (n = 6), Teheran (n = 3), Hormozgan (n = 4), Azerbaiejan-E-Sharqi (n = 4), and Kerman (n = 4). Reverse transcription-polymerase chain reactions (RT-PCR) were carried out using forward (5(prime)-CGCGTGGTTGTGGTCAACCC-3(prime)) and reverse (5(prime)-CCYGCAACCGAGGAAGATCC-3(prime)) primers designed in conserved regions of the coat protein gene according to the sequence of a CABYV reference isolate (3) and 3 other unpublished CABYV sequences. RT-PCR experiments yielded an expected 479-bp product similar to the fragment amplified with extracts from the reference isolate. No amplification of the product occurred from healthy plant extracts. To our knowledge, this is the 1st report of the occurrence of CABYV in Iran on various cucurbit species. The high frequency (46.2 percent) with which CABYV was detected in the samples assayed indicates that this virus is one of the most common virus
infecting cucurbits in Iran.

References:
(1) H. Lecoq et al. Plant Pathol. 41:749, 1992
(2) M. A. Mayo and C. J. D'Arcy. Page 15 in: The Luteoviridae. H. G. Smith
and H. Barker, eds. CAB International Mycological Institute, Walli

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[The cucurbit crop plants mentioned in this report are melon (_Cucumis melo_), cucumber (_C. sativus_), squash (_Cucurbita pepo_), and watermelon (_Citrullus lanatus_). They develop yellows symptoms when infected by cucurbit aphid-borne yellows virus (family: _Luteoviridae_, genus: _Polerovirus_, CAYBV).

CABYV was widely distributed with high frequency (nearly 50 percent of samples tested) in these 4 cucurbit species in the major growing areas of Iran. This conclusion is based on an extensive survey by ELISA throughout Iran conducted during 2001 to 2004.

CABYV was first reported in France in 1992. So far, it has been recorded in other European countries (including Greece, Spain and Cyprus) and African countries (including Tunisia, Morocco, Sudan, and Zambia) and in the USA
(California). Typical symptoms of CABYV on cucurbits include yellowing and thickening of old leaves. The major veins of these leaves remain green. These symptoms can be masked by mixed infection with other cucurbit viruses, and this was noted in the current study. Yield reduction in infected cucumber crops can reach about 50 percent. Major vegetable species susceptible to CABYV include watermelon, muskmelon, cucumber, zucchini
squash and lettuce (_Lactuca sativa_). CABYV can be transmitted persistently by the aphid _Aphis gossypii_ with great efficiency and also by the aphid _Myzus persicae_. CABYV is not transmitted mechanically. The source of the virus is unknown, possibly wild cucurbits. Resistant curcubit cultivars are not available, but sources of resistance to CABYV have been identified in melon accessions.

Map: Iran <http://worldatlas.com/webimage/countrys/asia/ir.htm>

Links:
<http://www.ipm.ucdavis.edu/PMG/r116102111.html>
<http://www.ipgri.cgiar.org/pgrnewsletter/article.asp?id_article=7&id_issue=138>
<http://www.iita.org/info/virology/pdf_files/213-232.pdf>
<http://www.umresearch.umd.edu/CGC/conferen/c96dise.htm#paper19>
- Mod.JAD]

[see also in the archive:
Cucurbit viruses CYSDV, CVYV - Cyprus: 1st reports 20060320.0868
2005
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Cucurbit aphid-borne yellows virus - Tunisia 20050627.1818
2004
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Cucurbit virus diseases - Sudan 20040918.2589
Cucurbit aphid-borne yellows virus - Spain (Murcia) 20040811.2224]