Instituto de Fitopatología y Fisiología Vegetal (IFFIVE-INTA), Cno. 60 Cuadras Km 5 1/2, 5119 Córdoba, Argentina
IFFIVE-INTA and Facultad de Agronomía y Veterinaria, Universidad Nacional de Río Cuarto, 5800 Río Cuarto, Córdoba, Argentina
A virus causing chlorotic mottling symptoms on sunflower was found in various locations in Argentina. Symptoms were small chlorotic spots, yellow blotches on leaves, and plant stunting. Virus transmission efficiency by mechanical inoculation was 73 to 100%, and by Myzus persicae was 31 to 49%. The host range included members of the Amaranthaceae, Asteraceae, Chenopodiaceae, and Solanaceae families. Electron microscopy of leaf dips from infected plants revealed flexuous particles 17 nm wide and 770 nm long. Cytoplasmic laminar aggregates and pinwheel inclusions were observed in ultrathin sections. Purified virus preparations analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis resolved a capsid protein of 33 kDa. A monoclonal antibody to aphid-transmitted potyviruses reacted with the capsid protein of this virus. In dot blot immunoassays, a polyclonal antiserum (early bleeding) reacted with infected sunflowers and weakly with Bidens mottle potyvirus, but not with either maize dwarf mosaic potyvirus or potato virus Y. The evidence suggests that a potyvirus is infecting sunflower, and a partial characterization of the causal agent is reported.