Two diseases of dimorphotheca caused by lettuce mosaic potyvirus and tomato spotted wilt tospovirus

Abstract

In 1997, virus-like symptoms were observed in dimorphotheca plants (Dimorphotheca sinuata) at two different locations in Greece. In a greenhouse near Heraklion (Crete), plants showed chlorotic patches mainly in the older leaves, and a mild stunting; near Katerini (Macedonia), garden plants showed chlorotic rings. Sap inoculation of healthy dimorphotheca plants with extracts from diseased plants from the two regions, reproduced each of the two diseases. Examination by electron microscopy (EM) of samples from diseased plants from the first region revealed filamentous particles, whereas samples from the second region showed quasi-spherical particles. The filamentous particles were decorated in EM with antibodies specific to lettuce mosaic potyvirus (LMV). Samples from the second location reacted with antibodies specific to tomato spotted wilt tospovirus (TSWV) in ELISA tests. It is concluded that LMV and TSWV are the causal agents of the disease noticed in Heraklion and in Katerini, respectively.