Viroid-Like Rnas Associated with the Citrus Exocortis Disease Reaction in Citron

Abstract

The citrus exocon is viroid (CEV) has been well characterized as a 371 nucleotide transmissible RNA that produces stunting and leaf epinasty and rugosity in Gynura aurantiaca and citron (Citrus medica). Field isolates of the exocortis disease designated as mild or moderate by the reaction on the citron indicator, which in most cases are not transmissible to Cynura, display 1-3 sub CEV-RNA species which migrate in PAGE under denaturing conditions in the region of viroid RNA . Two of the isolaled RNA species are characterized as viroid-like by Cf-11 cellulose chromatography properties, the resolution of circular and linear molecular forms and transmission to citron. These data suggest that the citrus exocortis disease reaction may be induced by a complex of either distinct or CEV-related viroid- like RNA's .