A Bromoviridae member associated with chlorotic leaf symptoms on sunflowers

GIOLITTI, F.; NOME, C.F.; VISINTIN, G.; DE BREUIL, S.; BEJERMAN, N.; LENARDON, S.

Mar del Plata

Conferencia; 18th International Sunflower Conference; 2012

ASAGIR

A bromovirus isolated from sunflower (Helianthus annuus L.) was characterised and shown to be highly related to Pelargonium zonate spot virus (PZSV), a virus reported in Italy, Spain, France, USA and Israel. Sunflower plants showing chlorotic concentric ring and linear pattern symptoms were observed near Paraná city (Entre Ríos Province) in commercial sunflower crops. This was the first observation of this type of symptoms in sunflower in Argentina, but similar ones have been reported in Africa and Mexico. The aim of this study was to characterize this new sunflower disease. The characterization was based on virus transmission, host range, electron microscopy and comparison of its sequence with those of related viruses. Virus transmission efficiency by mechanical inoculation to sunflower plants at the V2 vegetative stage was nearly 100%. Seed transmission was negative as plants derived from seeds of systemically infected plants showed no symptoms. A host range including 27 species of the families Amaranthaceae, Asteraceae, Chenopodiaceae, Cucurbitaceae, Dipsacaceae, Fabaceae and Scrophulariaceae was tested, and 59.26% of the inoculated species showed positive plants to viral infection. Electron microscopy of rapid preparations from samples enriched with the virus revealed high concentration of quasi-spherical particles of 33 nm diameter. Total RNA extracted from a viral enrichment sample was pyrosequenced, and 54,506 sequences were obtained, three of them with 3383, 2433 and 2655 pb showed 90.0%, 94.7% and 93.9% of identity with RNA1, RNA2 and RNA3, respectively, of PZSV isolated in Apulia, Italy. These results indicate that the virus associated with chlorotic concentric ring and linear patterns symptoms in sunflower is PZSV, a member of the Bromoviridae family, Anulavirus genus. This is the first mention of a PZSV infecting sunflower and is the first mention of this virus in Argentina. This study provides basic information on this new sunflower disease in Argentina. These results will allow further epidemiological and characterization studies of the disease.