Serological and molecular detection of Turnip yellows virus in rapeseed fields in Kermanshah Province, Iran

Members of the genus Polerovirus, including Turnip yellows virus (TuYV), are important viruses on field crops. They are being transmitted by aphids in a circulative non-propagative manner. During 2018 and 2019, 32 leaf samples from rapeseed (Brassica napus) and one sample from wild mustard (Sinapis arvensis) were collected in Kermanshah Province, Iran. The samples were tested by a TAS-ELISA kit (DSMZ) that detects four poleroviruses including TuYV, Beet mild yellowing virus (BMYV), Beet western yellows virus (BWYV) and Beet chlorosis virus (BChV). A positive reaction was observed for the wild mustard and seven rapeseed samples. Myzus persicae and Brevicoryne brassicae were used for virus transmission. The virus was successfully transmitted by the aphids to rapeseed and radish but not to sugar beet plants. In IC-RT-PCR using a specific primer pair, a 780 bp fragment was amplified from wild mustard and two rapeseed samples. The two nucleotide sequences from rapeseed and wild mustard had 99.4% identity to each other and showed up to 97.2% similarity to TuYV isolates previously deposited in GenBank from fenugreek, rapeseed, pea and chickpea plants in Australia. In phylogenetic analysis based on the nucleotide sequences of ORF0, two Iranian isolates of TuYV were placed in the same clade with other TuYV isolates and were distinct from other poleroviruses such as BMYV, BWYV and BChV. In this study, for the first time in Kermanshah Province, TuYV was identified in Iranian rapeseed fields based on nucleotide sequencing of the P0 coding region.