New begomoviruses
Many new begomoviruses have recently been described from various parts of the world, on Cucurbitaceae, Malvaceae or Solanaceae. For convenience, they have been gathered here. For the moment, the main difficulty in assessing their importance is the lack of information on the extent and severity of the diseases they may cause on the crops.
Cucurbit leaf crumple begomovirus in California (US)
In 1998, a new bipartite begomovirus tentatively called Cucurbit leaf crumple begomovirus was observed in cucurbits in the Imperial Valley of California, US (Hernandez et al., 2000)
Cucurbit leaf curl begomovirus in USA (Arizona, Texas) and Mexico
In 1998-1999, virus symptoms were observed on pumpkin (Cucurbita pepo) in Arizona (US), and on melons (Cucumis melo) in Texas (US) and Coahuila (MX). Symptoms were similar to those caused by Squash leaf curl begomovirus (EPPO A1 quarantine pest) described in Arizona in 1981. Cucurbit plants were also infested by whiteflies. Molecular studies (PCR and nucleotide sequence comparisons) revealed the presence of a new begomovirus, tentatively called Cucurbit leaf curl begomovirus (Brown et al., 2000).
Cotton leaf curl begomovirus - Sudan
In Sudan, cotton leaf curl disease was first reported in 1931. Symptoms on cotton plants were characterized by vein thickening and leaf curling. It was shown that Bemisia tabaci (EPPO A2 quarantine pest) could transmit the disease to cotton, okra and several weeds. However, the probable begomovirus aetiology was not ascertained. During 1994-1996, 4 cotton samples showing typical symptoms of the disease were collected form different fields in the region of Gezira, in Central Sudan. Molecular studies (PCR, nucleotide sequence analysis) showed that the 4 isolates corresponded to a new single monopartite begomovirus. Its closest relatives were Althaea rosea enation begomovirus from Egypt (79% similarity) and Cotton leaf curl begomovirus – Pakistan (66%). This new virus was tentatively called Cotton leaf curl begomovirus - Sudan (Idris ; Brown, 2000).
Pepper yellow leaf curl begomovirus in Thailand
In 1995, pepper plants (Capsicum annuum) showing symptoms of yellow leaf curl were observed at Kanchanaburi in central Thailand. 3 naturally infected pepper plants were collected and virus cultures were maintained on pepper plants. The virus was transmitted by Bemisia tabaci (EPPO A2 quarantine pest). Molecular studies (PCR, nucleotide sequence comparisons with 28 well known begomoviruses) revealed the presence of a new begomovirus. Its closest relative was Tomato leaf curl virus from Taiwan (85 % sequence similarity). This new virus was tentatively called Pepper yellow leaf curl begomovirus (Samretwanich et al., 2000).
Tomato curly stunt begomovirus - South Africa
In South Africa, preliminary reports in 1997 suggested that Tomato yellow leaf curl begomovirus (TYLCV - EPPO A2 quarantine pest) was present. In 1998, 140 ha of tomato fields in the region of Onderberg (Mpumalanga) were studied for the possible presence of TYLCV-Israel. Disease incidence ranged from less than 1% to 50 %. Yield losses in individual plants ranged from negligible to 100 %. Molecular studies (PCR, nucleotide sequence comparisons) of two isolates were carried out. They showed that the 2 isolates were indistinguishable, and that the virus present was a distinct begomovirus (it shared less than 78% sequence identity with other well studied begomoviruses). This virus was tentatively called Tomato curly stunt begomovirus - South Africa (Pietersen et al., 2000).
Tomato leaf curl begomovirus - Barbados
In September 1998, tomato plants showing symptoms of severe leaf curling without marginal chlorosis were observed in Barbados. Symptoms were often associated with populations of Bemisia tabaci (EPPO A2 quarantine pest). Molecular studies revealed the presence of a new begomovirus which was tentatively called Tomato leaf curl begomovirus - Barbados (Roye et al., 2000).
Sources
Brown, J.K.; Idris, A.M.; Olsen, M.W.; Miller, E.; Isakeit, T.; Anciso, J.; (2000) Cucurbit leaf curl virus, a new whitefly transmitted geminivirus in Arizona, Texas, and Mexico.
Plant Disease, 84(7), p 809.
Hernandez, N.A.; Sudarshana, M.R.; Guzman, P.; Gilbertson, R.L. (2000) Generation and characterization of infectious clones of Cucurbit leaf crumple virus, a new bipartite geminivirus from the Imperial Valley of California. Abstract of a paper presented at the APS 2000 Annual Meeting in New Orleans, Louisiana, 2000-08-12/16, USA.
Phytopathology, 90(6), S 35.
Idris, A.M.; Brown, J.K. (2000) Identification of a new, monopartite begomovirus associated with leaf curl disease of cotton in Gezira, Sudan.
Plant Disease, 84(7), p 809.
Pietersen, G.; Idris, A.M.; Krüger, K.; Brown, J.K. (2000) Tomato curly stunt virus, a new begomovirus of tomato within the Tomato yellow leaf curl virus-IS cluster in South Africa.
Plant Disease, 84(7), p 810.
Roye, M.E.; Henry, N.M.; Burrell, P.D.; Mc Laughlin, W.A.; Nakhla, M.K.; Maxwell, D.P. (2000) A new tomato-infecting begomovirus in Barbados.
Plant Disease, 84(12), p 1342.
Samretwanich, K.; Ciemsombat, P.; Kittipakorn, K.; Ikegami, M. (2000) A new geminivirus associated with a yellow leaf curl disease of pepper in Thailand.
Plant Disease, 84(9), p 1047.