Incidence of Beet western yellows virus (BWYV) in alfalfa fields of Lorestan and Ilam provinces (West Iran) and its taxonomical place using coat protein gene

During 2011 and 2012, a total of 932 alfalfa leaf samples with yellows, reddening, necrosis and stunting were collected from Lorestan and Ilam provinces. Samples were tested by tissue blot immuno assay (TBIA) using 5G4 monoclonal antibody (a broad spectrum antibody against wide range of legume infecting luteoviruses) in which 35% of random leaf samples showed positive reaction. Molecular analysis confirmed the infection of samples by Beet western yellows virus-BWYV (Polerovirus genus). Inoculation tests using green peach aphids (Myzus persicae) induced vein clearing in sugar beet cv. IC1, vein yellowing in canola (cultivar Otsubu), stunting in white mustard and severe vein yellowing in alfalfa cv. Hamedani. A DNA fragment with the expected length of 560 bp corresponding to BWYV coat protein (CP) gene was amplified. PCR-RFLP analysis using Sma I also revealed BWYV specific profile for the studied isolates. The identity of BWYV-CP gene was 98.6 to 99.4 %.among the Iranian isolates at nt levels The lowest and highest sequence identities were 92.5 % and 97 % with isolates from Italy (L40020) and FL1 (X13063) from France, respectively. Phylogenetic tree using NJ method showed that Iranian BWYV isolates clustered into two subgroups. This is the first report of BWYV occurrence in alfalfa fields in Iran and their CP nucleotide sequences.