OCCURRENCE OF BEET WESTERN YELLOWS VIRUS IN JAPANESE HOP (HUMULUS SCANDENS) IN CHINA

Abstract

Beet western yellows virus (BWYV) naturally infects Beta vulgaris, Raphanus sativus, Capsella bursa-pastoris and a number of common weed species. In autumn 2011, Japanese hop [Humulus scandens (Lour.) Merr] plants showing mosaic symptoms on young leaves were observed in the West Campus of the China Agricultural University of Beijing (China). Total RNA was extracted from symptomatic leaves and screened by RT-PCR with degenerate primer pairs to detect poty-, potex-, tobamo-, cucumo-, polero- and tospoviruses. A specific RT-PCR product (1,384 bp) was obtained only with polerovirus primers designed to amplify a fragment including the partial RNA-dependent RNA polymerase (RdRp) gene, an intergenic non coding region and the coat protein (CP) gene (Zhou et al., 2011). Sequence analysis (GenBank accession No. KC210049) confirmed the presence of BWYV in the analysed samples. The CP gene of the BYWV isolate under study had the highest identity with a BWYV isolate from Inner Mongolia (92.1%) (EU636991) and another BWYV isolate from Beijing (90.6%) (ADR74372.1). whereas the partial RdRp sequence had the highest identity with a BWYV isolate from Beijing (98.3%) (EF051249.1). No RT-PCR products were obtained from healthy plants. To our knowledge, this is the first report on the natural occurrence of BWYV in H. scandens. As H. scandens is one of the most common weeds in China, management of BWYV in or near sugar beet fields or other crop hosts should include the removal of this weed.