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October 30, 2003
From: American Phytopathological Society, Plant Dis. Notes 87:1397, 2003 [edited]

First report of a Geminivirus associated with Leaf Curl in Baja California Peninsula tomato fields
R. J. Holguin-Pena & R. Vazquez Juarez, Centro de Investigaciones Biologicas del Noroeste, La Paz, B.C.S. 23000, Mexico; and R. F. Rivera-Bustamante, Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Irapuato, Guanajuato 36500, Mexico. Plant Dis. 87:1397, 2003; published on-line as D-2003-0902-01N, 2003. Accepted for publication 9 Aug 2003.

Since November 2001, geminivirus-like symptoms (stunting, reduced leaf size, and leaf curling "chino") have been observed in tomato (_Lycopersicon esculentum_ Mill.) plantings in Baja California Sur, Mexico.

Samples of symptomatic plants were collected from commercial fields and analyzed by traditional and molecular methods for the presence of geminiviruses. Inocula prepared from infected plants were experimentally transmitted to tomato seedlings and _Datura stramonium_ by mechanical inoculation and whitefly transmission. Leaf curling and interveinal chlorosis symptoms similar to those found in the field were observed in inoculated tomato and _D. stramonium_.

DNA from infected plants was extracted and analyzed by polymerase chain reaction (PCR) and electrophoresis using degenerate primers PALIv1978/PARIc494 (1). PCR fragments of the expected size (1.1 kb) for the common region (CR) were obtained from 28 of 64 plants, cloned and sequenced (GenBank Accession No. AY336088).

Comparisons of CR sequences with the NCBI database by using BLAST and MegAlign (DNASTAR, London) indicated that the Baja Californian isolates were New World bipartite begomoviruses sharing the highest nucleotide sequence identity (93 percent) with a partially characterized geminivirus (Tomato severe leaf curl virus (ToSLCV); GenBank Accession No. AF130415) from Guatemala.

Reference:
(1) M. R. Rojas et al. Plant Dis. 77:340, 1993.

[ToSLCV strains have also been reported from Guatemala, Honduras, Nicaragua, and Cuba. Cucumber (_Cucumis sativus_) and tomato are natural hosts. These strains likely originated in Central America and the Caribbean region. The genomes of these viruses are either monopartite or bipartite, the viruses are transmitted by whiteflies (_Bemisia tabaci_), and they infect a range of dicotyledonous plants. Disease management involves procedures to delay infection, regulated applications of insecticides, use of biopesticides (parasitoids and predators), and planting resistant cultivars if they are available.
Additional references relating to ToSLCV and geminivirus disease management: <http://www.plantmanagementnetwork.org/pub/php/management/2003/tomato>
<http://gemini.biosci.arizona.edu/viruses/toslcv/index.htm> - Mod.DH]