Plant Protection Institute, NAGREF, 71003 Heraklion, Crete, Greece
Aristotle University of Thessaloniki, Faculty of Agriculture, Plant Pathology Laboratory, 54 006 Thessaloniki, Greece
Benaki Phytopathological Institute, Laboratory of Virology, 14 561 Kifissia, Greece
In late summer 2000, tomato (Lycopersicon esculentum Mill.) grown in greenhouses in Ierapetra, Tympaki, and Chania (Crete) showed leaf curling, reduced leaf size, yellowing, shortened internodes, and a bushy appearance. More than 30 ha of tomato greenhouses were affected and the disease incidence ranged from 15 to 60% with estimated crop losses of over $500,000. Similar symptoms were observed in tomato samples from Marathon (Attiki) and Southern Peloponnese. All greenhouses with infected plants were infested with high populations of Bemisia tabaci (Gennadius), which were also observed outside the greenhouses on several weeds. Tomato symptoms were similar to those caused by Tomato yellow leaf curl virus (TYLCV). The assumed virus could not be transmitted mechanically but successful transmission was obtained by grafting onto healthy tomato plants. Over 100 samples of symptomatic tomato plants collected from Crete and southern Peloponnese gave positive reactions when tested by ELISA using monoclonal antibodies to TYLCV-European (Adgen Ltd). The serological results were confirmed by PCR using two pairs of primers, universal degenerate (1) and MA 13 and MA 17 (2), amplifying different parts of the virus genome. The restriction fragment length polymorphism (RFLP) analysis (AluI, HaeIII, and TaqI) of the 541 bp amplicon obtained with the degenerate primers showed patterns similar to TYLCV-Is (Israeli species). The second pair of primers gave the expected 348 bp product, which was sequenced. Sequence comparisons revealed 99% identity with TYLCV-Is (EMBL no. X15656, X76319). The resulting sequence was at least 97.7% identical to sequences of TYLCV isolates from the Dominician Republic (EMBL no. AF024715), Cuba (EMBL no. AJ223505), Portugal (EMBL no. AF105975), Iran (EMBL no. AJ13271), and Spain (EMBL no. AF071228). The disease appeared for the first time in 1992 in Tymbaki, but was limited to very few plants in one glasshouse. However, the cause was not determined. To our knowledge, this is the first report of TYLCV of the Begomovirus genus in Greece.
References: (1) D. Deng et al. Ann. Appl. Biol. 125:327, 1994. (2) J. Navas-Castillo et al. J. Virol. Methods 75:195, 1998.