July 15, 2003
Source: American Phytopathological Society DISEASE NOTES [edited]


A new Tomato yellow leaf curl virus strain in Southern Spain
G. Morilla, C. Antúnez, and E. R. Bejarano, Departamento de Genetica Universidad de Malaga, 29071 Malaga, Spain; and D. Janssen and I. M. Cuadrado, CIFH "La Mojonera" El Ejido, Almeria, Spain. Plant Dis. 87:1004, 2003; published on-line as D-2003-0611-01N, 2003. Accepted for publication 19 May 2003.

Tomato yellow leaf curl disease (TYLCD) has affected tomato crops annually in southern Spain since 1992, when Tomato yellow leaf curl Sardinia virus (TYLCSV-ES) was first described. In 1997, the presence of a different begomovirus species (TYLCV-[ES7297]) was reported in common bean (_Phaseolus vulgaris_). In 1999, TYLCV-[ES7297] was found in pepper (_Capsicum annuum_) (2).

In September 2002, we observed tomato plants of TYLCD tolerant tomato cultivars (Kampala and Tiway) showing strong TYLCD symptoms (shortened internodes, curling of leaflet margins, and leaf blade reduction).

Samples from 90 of these plants were collected from greenhouses located in the Province of Murcia and analyzed by Southern blot using the intergenic region of TYLCSV-ES[2] and TYLCV-[ES7297] as specific probes. Positive signals were obtained for TYLCV-[ES7297] and TYLCSV-ES[2] in 88 and 23 of the plants, respectively.

Samples from 8 TYLCV single-infected plants (4 'Kampala' and 4 'Tiway') were analyzed by polymerase chain reaction using a pair of primers (OTYA7:GCTCCCTGAATGTTCGGATGG A and OTYA8: ATCATGGATTTACGCACAGGGG) designed to amplify a 1.9-kb fragment of any isolate of TYLCV/TYLCSV.

Subsequent restriction fragment length polymorphism analysis of the amplification products yielded a restriction pattern different from that obtained for TYLCV-[ES7297]. Fragments from the 8 samples were sequenced and showed 97.9 percent identity to a TYLCV strain previously reported in Israel (X15656) (1) and only 92.7 percent identify with TYLCV-[ES7297].

To our knowledge, this is the first report that this strain of TYLCV has been detected in Spain.

[TYLCV-infected tomato plants grow slowly and are stunted and dwarfed. Leaves are greatly thickened and leathery. Yield losses are extreme because fruit production is drastically reduced and the fruit that is produced is usually not marketable. The virus is present in most tropical production areas worldwide. A concerted effort is being made to locate sources of tolerance/resistance to TYLCV; _L. cheesmanii_ ssp. minor, _L. hirsutum_, _L. peruvianum_, and _L. pimpinellifolium_ are being assessed. The replication-associated protein (Rep) from TYLCV-Sardinia is being evaluated in transgenic tomatoes transformed with Rep. Hopefully these measures will result in tomato selections that are tolerant to virus infection and also able to sustain good yields.
A useful reference: < www.pubmedcentral.nih.gov/articlerender.fcgi?artid=156158 > - Mod.DH]