Relationships among the viroids derived from grapevines

There have been numerous reports of grapevine viroids, describing physical and biological properties suggestive of similar or identical molecular forms. With consideration f these properties and the applica-tion of random-primed and specific DNA probes, four major groups of grapevine viroids have been defined. Designations which can be used to describe distinct viroids within the four groups include (i) CEVd-g, a grapevine isolate of citrus exocortis viroid, (ii) GVd-c, a grapevine viroid recovered from cucumber, and AGVd, Australian grapevine viroid, (iii) GYSVd-1 and GYSVd-2, two viroids inducing yellow speckle disease and (iv) HSVd-g, a grapevine isolate of hop stunt viroid