Virus diseases newly reported from Egypt
The EPPO Secretariat was recently informed by Dr Abdel-Salam from the University of Cairo (EG) of the occurrence of the following new virus diseases in Egypt.
Banana streak virus (Badnavirus)
In Egypt, banana plants showing chlorotic and necrotic streaks on the leaves were observed in the field. Banana streak virus was isolated from a stunted banana plant, heavily infested by Planococcus citri (a known vector of the disease), in the Souhag governorate. Serological and molecular tests (DBIA, TBIA, PCR) confirmed the identity of the virus, and pathogenicity tests were conducted in the greenhouse. This is the first report of Banana streak virus in Egypt.
Beet necrotic ringspot virus (a new tentative Ilarvirus)
In Egypt, sugarbeet (Beta vulgaris) is an expanding crop. It is affected by several viruses including Beet curly top virus (Curtovirus), Beet yellows virus (Closterovirus), Beet western yellows virus (Polerovirus), Cucumber mosaic virus (Cucumovirus) and Beet necrotic yellow vein virus (Benyvirus). Recently, sugarbeet plants showing ringspot, line pattern, bright mosaic and reduced growth were observed in Kafr El-Sheikh, Giza and Fayoum governorates. A new ilarvirus, tentatively called Beet necrotic ringspot virus was isolated from diseased plants. In glasshouse experiments, the virus could be transmitted mechanically and via Thrips tabaci (but not via Myzus persicae). In preliminary tests, it appears that the virus is not seed-transmitted. In mechanical inoculation studies, the virus could be transmitted to a wide range of plants (21 species from Amaranthaceae, Asteraceae, Chenopodiaceae, Cucurbitaceae, Fabaceae, Rosaceae and Solanaceae).
Squash leaf curl virus (Begomovirus – EPPO A2 List)
In recent years, both the quality and yield of cucurbit crops in Egypt have been drastically reduced due to virus diseases associated with whitefly infestations. In particular, squash plants (Cucurbita pepo) have been showing symptoms typical of those of squash leaf curl observed in the Americas (i.e. severe stunting, leaf curling, enations). Laboratory studies were done in Egypt to identify the causal agent. A virus isolate was obtained from squash plants growing in the experimental farm of the Faculty of Agriculture (Giza) and studied with serological and molecular methods (ELISA, PCR with specific primers, IC-PCR, DNA sequencing, molecular hybridization). Results confirmed the presence of Squash leaf curl virus in diseased plants. In addition, it was observed under glasshouse conditions that the disease was transmitted by Bemisia tabaci. Phylogenetic analysis revealed very close similarities between the Egyptian isolate and isolates from USA. This could suggest an introduction from the Americas to Egypt. The EPPO Secretariat had previously no data on the occurrence of Squash leaf curl virus in Egypt. In the EPPO region to date, this virus is only known to occur in Israel (see EPPO RS 2003/117).
Sources
Abdel-Salam AM, Abdallah NA, Soliman DZR, Rezk AAS (2006) The incidence of squash leaf curl begomovirus (SqLCV) in Egypt. Arab Journal of Biotechnology 9(2), 375-388.
Abdel-Salam AM, Abdel-Kader HS, Saghir SM (2005) Biological, serological, and molecular detection of Banana streak badnavirus in vegetatively propagated banana plants in Egypt. Egyptian Journal of Virology 2(1), 255-265.
Abdel-Salam AM, El-Shazly MA, Abdel-Kader HS (2005) Beet necrotic ringspot virus, a new ilarvirus infecting sugar beet in Egypt: biological, biochemical, serological, and genomic studies. Arab Journal of Biotechnology 9(2), 395-414.