Occurrence of Tomato Infectious Chlorosis in Europe.

A new virus of tomato and other crop and weed hosts was found in California in 1993. Tomato plants affected by the virus exhibited interveinal yellowing, necrosis and severe yield losses. The virus was described as tomato infeciious chlorosis virus (TICV), and is transmitted in a semi-persistent manner by the greenhouse whitefly, Trialeurodes vapomriorum. A tomato plant showing unusual malformation and leaf reddening, stunting, and poor fruit set was observed in a glasshouse at Albenga, Liguria, north western Idy. The plant was shown to be infected with a clostero-like virus transmitted by T. vaporariorum. The Italian virus isolate was transmitted to tomato and a few other members of the Solanaceae. The virus particle size, insect transmission and lack of a serological response to beet pseudo yellows virus (BPYV) and lettuce infectious yellows virus (LIYV) was similar to the TICV from California. ELISA tests demonstrated that antiserum against TICV reacted with tomato tissue infected with TICV from California and the Italian isolate, but not with tissue from healthy plants. Complementary DNA corresponding to the virion RNA isolated from TICV-infected tissue was cloned. Digoxigenin-labeled riboprobes reacted specifically with RNA extracted from TICV-infected plants and from plants infected with the Italian isolate in dot blot analyses. No hybridization reactions were observed with other whitefly-transmitted closteroviruses including BPYV, LIW, lettuce chlorosis, or cucurbit yellow stunting disorder.