D. Kostova1*, V. Masenga2, R.G. Milne2 and V. Lisa2
1 Maritza Institute for Vegetable Crops, Plovdiv, Bulgaria
2 Istituto Fitovirologia Applicata CNR, Torino, Italy
Accepted: 11 Jun 2001
Unusual virus-like symptoms were observed in crops of cucumber (Cucumis sativus) under plastic and pepper (Capsicum annuum) in the open, near Plovdiv, southern Bulgaria, in summer 2000. Cucumber plants showed shortened internodes, severe dwarfing, epinasty, wrinkled epidermis and reduced leaf size (Fig. 1). The disease appeared on c. 30% of plants, at flowering, in two localities, on cvs T-19 (pickling type) and Gergana (salad type). On pepper, severe vein clearing and small yellow spots or yellow mosaic were seen sporadically on young leaves at both localities.
Leaf samples were desiccated over calcium chloride, brought to Torino, and sap-inoculated to test plants. Subsequent isolates were designated P6 (cucumber) and P15 and P27 (pepper). The isolates proved to be similar except that P27 gave more severe reactions and higher virus titres. Nicotiana benthamiana, N. clevelandii, N. glutinosa and N. megalosiphon reacted by developing yellow local lesions followed by vein clearing, mottling, mosaic and stunting. Chenopodium quinoa, Datura stramonium, Petunia hybrida and Ociymum basilicum gave local lesions only. The symptoms resembled those reported for Eggplant mottled dwarf virus (EMDV; a rhabdovirus). Pepper cv Quadrato d'Asti reacted with severe symptoms to the pepper isolates, and cucumber cv Marketer reacted severely to the cucumber isolate, but pepper was not infected by the cucumber isolate and vice versa.
Electron microscopy of negatively stained crude extracts revealed large numbers of rhabdovirus-like particles (Fig. 2) and free nucleocapsids but no other virus-like particles. Western blots were prepared using EMDV antiserum DSMZ As 0136, kindly supplied along with the homologous virus by Dr. S. Winter, DSMZ, Braunschweig. The homologous antigens and those of our three isolates reacted similarly.
EMDV has been reported in pepper and cucumber in Italy (Roggero et al., 1995) and is known to infect several crops in the Mediterranean area, including cucumber and tobacco in Greece (Katis et al., 2000) and eggplant in Turkey (Erkan, 1988).
Roggero P, Milne RG, Masenga V, Ogliara P, Stravato VM, 1995. First reports of eggplant mottled dwarf rhabdovirus in cucumber and in pepper. Plant Disease 79: 321.
Erkan S, 1988. A virus disease of eggplant in Turkey: eggplant mottled dwarf virus. Capsicum Newsletter 7, 93-94.
Katis N.I, Chatzivassiliou EK, Clay C, Avgelis A, Manossopoulos I, Lecoq H, 2000. Occurrence of eggplant mottled dwarf nucleorhabdovirus (EMDV) in tobacco and cucumber in Greece. Phytopathologia Mediterranea 39, 318.
©2001 The Authors