Solanum nigrum: an indigenous weed reservoir for a tomato yellow leaf curl geminivirus in southern Spain

A tomato yellow leaf curl geminivirus (TYLCV-AL), was first identified in tomato plants in Almeria, southern Spain in 1992. This virus is transmitted by the tobacco whitefly, Bemisia tabaci (Gennadius), and is presently infecting tomato crops throughout the south eastern region of Spain. Solanum nigrum, collected from a field in south east Spain and exhibiting leaf curl symptoms, was squash blotted onto nylon membrane and gave a positive signal when hybridised to a TYLCV-Is DNA probe. Laboratory tests showed B. tabaci to transmit TYLCV-AL from infected tomato plants to S. nigrum seedlings. The virus could then be acquired by B. tabaci and transmitted back from infected S. nigrum plants to tomato, inducing typical TYLCV symptoms. These results indicate the importance of S. nigrum as a weed host/reservoir for a TYLCV and its possible role in the spread of this virus within Europe.