Identification and characterization of a new strain of sunflower chlorotic mottle virus, a potyvirus infecting asteraceae in Argentina

Abstract

Sunflower (Helianthus annuus L.) plants with chlorotic ringspot symptoms were observed during the 2005– 2006 crop season in the Southeast of the province of Buenos Aires, Argentina. Symptomatic plants were tested by biological, serological and molecular assays, and the virus isolated was identified as a potyvirus closely related to Sunflower chlorotic mottle virus, common isolate (SuCMoV-C), the most prevalent virus in sunflower crops in the country. Infected plants were serologically positive when probed with a SuCMoV-C antiserum. In the 3¢-terminus region, 1304 nucleotides (nt) were sequenced, and it includes the C-terminal region of the nuclear inclusion b protein (NIb) gene (240 nt), the whole capsid protein (CP) gene (807 nt) and a 3¢-non-coding region (3¢-NCR) with 257 nt excluding the poly (A) tail. The CP of the Sunflower potyvirus causing chlorotic ringspot (CRS) shared 94.8% aa identity with SuCMoV-C and 89.2% with SuCMoV-Zi. The 3¢-NCR shared 94.2% nt sequence identity with SuCMoV-C. A RT-PCR ⁄ RFLP assay with PvuII and EcoRV restriction enzymes successfully differentiated SuCMoV-C and the virus isolate causing CRS symptoms. This potyvirus was identified as a new SuCMoV strain, provisionally designated SuCMoVCRS.