Properties and serological relationships of Australian and Californian soil-borne viruses of the grapevine and arabis mosaic virus

Abstract

Grapevines infected with soil-borne viruses were collected in Australia and California, and transmissions made from them to a range of herbaceous hosts. Positive transmissions were obtained more readily in the winter than in the summer, and Chenopodiurn quinoa was found to be the most sensitive test plant at all times. An increased transmission rate was obtained if leaves from infected vines were first homogenized in 5% nicotine base, and the virus concentrated by ultracentrifugation. Each of seven isolates differed in the symptoms produced on herbaceous hosts. The reactions of Gomphrena globosa to four Australian isolates were studied in detail. In cross-protection experiments one of the Australian isolates protected G. globosa plants from invasion by two of the others, and partially protected it from invasion by the third. Arabis mosaic virus, however, did not protect this host from infection by one of the Australian grapevine isolates. Three Australian and three Californian grapevine isolates and two English isolates of arabis mosaic virus were purified, and antisera prepared against them. The grapevine isolates were serologically identical, and all distantly related to arabis mosaic virus, as determined by immunodiffusion tests. The purified viruses were transmitted back to Mission grapevine seedlings and cuttings. The symptoms produced after 4 months were characteristic of the isolate, but were all of the fanleaf type.