The occurrence of three viruses in hop (Humulus lupulus) in China

Abstract

Forty‐two percent of leaf samples taken from hop cv. Qingdao Dahua growing in plantations in northeastern China in 1983‐1984 were infected with hop mosaic virus (HMV) and/or hop latent virus (HLV). Mosaic or line‐pattern symptoms were seen in some plants but only in spring and it is uncertain if the symptoms were caused by either virus which appeared in our studies to be similar, both serologically and in host range, to HMV and HLV described in Europe and North America. In host range studies, HMV infected Nicotiana clevelandii systemically without inducing symptoms. Occasionally it caused chlorotic spots in the inoculated leaves of Chenopodium quinoa and brown star‐point lesions in inoculated leaves of Phaseolus vulgaris cv. Topcrop, The virus was purified by PEG precipitation from extracts of N. clevelandii plants; yields were about 40‐120 mg/kg fresh leaves. The virus contained a single protein (estimated molecular weight 34 200) that was estimated to contain 272 amino acids with no methionine, and a single RNA species (estimated molecular weight 295 x 106) that represented c. 6% of the particle weight. HLV sometimes caused inconspicuous chlorotic spots in inoculated leaves of C. murale and local pinpoint lesions in P. vulgaris in winter only. A virus similar to alfalfa mosaic virus was isolated from leaves of hop cv. Golding and caused systemic necrotic symptoms in C. quinoa and C. amaranticolor, and systemic chlorotic spots in hop cv. Styrian.