LOOP-STRUCTURE IN SEROLOGICAL CLASSIFICATION-SYSTEM OF TYMOVIRUSES

Two newly described tymoviruses, Kennedia yellow mottle (KYMV) and Clitoria yellow vein viruses, can be fitted into the serological classification scheme recently proposed if it is extended to contain a loop-structure. KYMV forms a link between turnip yellow mosaic virus (TYMV) and some other viruses which are only distantly related to TYMV. Plantago mottle virus is closely related to Scrophularia mottle and ononis yellow mosaic viruses. The present knowledge on the serological interrelationships in the tymovirus group is summarized in a classification scheme in which the average serological differentiation indices of reciprocal tests are depicted as length units.