Poison hemlock virus Y (PHVY), a novel potyvirus from Iranian Conium maculatum (Apiaceae)

Poison hemlock (Conium maculatum L., Apiaceae) is native to temperate regions of Europe, West Asia and North Africa. During the 2015–2016 growing season, leaf samples of C. maculatum with mild mosaic and vein yellowing symptoms were collected from fields and pastures in the Bardsir region of Kerman Province (south-east Iran). The virions of one isolate of the virus, which we have named Poison Hemlock Virus Y (PHVY), were shown to be serologically related to potyviruses in ACP-ELISA tests using potyvirus-specific antibodies. Eight other viruses were not detected serologically in any samples. Mechanical transmission assays showed that the virus has a limited host range. Of the 12 test plant species mechanically inoculated, Chenopodium amaranticolor and three species of Apiaceae became infected. Groups of 10 Aphis gossypii or Myzus persicae given short-feeds on PHVY infected plants infected 20% and 15%, respectively, of test plants. The molecular weight of the viral coat protein (CP) was estimated by two methods to be 31 kDa. Electron microscopy showed that the partially purified virions were flexuous filaments c. 755 × 13 nm in size. Total RNA that was extracted from virus infected samples, and amplified in RT-PCR, gave three fragments, corresponding to the partial CI, HC-Pro and genomic 3′ terminal regions. The CP region of PHVY has the largest shared nucleotide (72.9%) and encoded amino acid (68.0%) identities with those of Lettuce mosaic virus. We conclude that PHVY is novel Potyvirus of the family Potyviridae.