Potyviruses and tobraviruses infecting ornamental Allium species in the United Kingdom.
In autumn 2013, a range of bulbs of ornamental Allium species was planted in the Royal Horticultural Society's garden at Wisley to assess their vigour and aesthetic qualities. The trial included 179 accessions of plant material, representing 32 species or hybrids, from 6 nurseries in the UK or The Netherlands. During April 2015, yellow flecking and striping with occasional reddening on the leaf surfaces and leaf curling was observed on many of the plants. From leaf samples collected from symptom-bearing plants of 20 accessions, RNA was extracted and tested by RT-PCR using broad-spectrum primers for carlaviruses and tospoviruses, potyviruses and tobraviruses. No samples tested positive for tospoviruses but all tested positive using at least one of the three other primer sets. A. jesdianum 'Pendjikent', A. nigrum and A. siculum (syn. Nectaroscordum siculum) tested positive using the carlavirus primers but it was not possible to sequence the product. The remaining amplicons of the expected size were directly sequenced in both directions and were identified by BLAST analysis. GenBank Accession Nos. KT223098, KT223099, KT223100, KT223101, KT223102 and KT223103 had 98, 98, 99, 92, 99 and 85% nucleotide sequence identity with Leek yellow stripe virus, Onion yellow dwarf virus, Ornamental onion stripe mosaic virus (OrOSMV), Pea early-browning virus (PEBV), Tobacco rattle virus and Turnip mosaic virus (TuMV), respectively. This is thought to be the first report of PEBV infecting Allium. The remaining viruses have been reported previously from Allium spp. However, with few exceptions such as Noda et al. (1989), the specific identity of ornamental hosts has not been reported and therefore this is the first report of many of these virus-host associations. This is also the first report of OrOSMV in the UK.