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Disease Detection and Losses

Detection and Comparison of Electrophorotypes of Hibiscus Chlorotic Ringspot Virus. S. S. Hurtt, U.S. Department of Agriculture, Agricultural Research Service, Florist and Nursery Crops Laboratory, Beltsville, MD 20705; Phytopathology 77:845-850. Accepted for publication 7 November 1986. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1987. DOI: 10.1094/Phyto-77-845.

Isolates of hibiscus chlorotic ringspot virus (HCRSV) were obtained from Hibiscus rosa-sinensis by mechanical inoculation to kenaf and Chenopodium quinoa. After isolation and serial passage in C. quinoa, the virus was avirulent on kenaf but reacted with HCRSV antiserum. Therefore, virus from H. rosa-sinensis, kenaf, and C. quinoa was purified and compared. Virions from the three hosts were indistinguishable by buoyant density in CsCl (1.34–1.35 g/cm³) and coat protein size in sodium dodecylsulfate polyacrylamide gel electrophoresis (34–35.5 kDa). Each host also contained three major double-stranded RNAs (molecular weights of 3.0, 1.4, and 1.1 × 10⁶). However, the electrophoretic profiles of purified preparations from each host were different when subjected to electrophoresis in agarose slab gels. Virions purified from H. rosa-sinensis separated into one major fast-migrating and one or two slower-migrating components, designated electrophorotypes. Virus from kenaf or from C. quinoa, after a prior passage in kenaf, migrated as one major electrophorotype (HCRSV-K) with a mobility like that of the major component from H. rosa-sinensis. Virus serially passed in C. quinoa was a mixture of several unique electrophorotypes. The fastest (HCRSV-F) and slowest (HCRSV-S) electrophorotypes were eluted and propagated in C. quinoa. Antibodies raised to HCRSV-F and -S were used to demonstrate that the antigens were serologically related but unique. Amino acid analysis showed that the aspartic acid and threonine content of HCRSV-F and -S also differed. This is the first report of host-associated variants of HCRSV.