EN
The very beginnings of plant virus nomenclature and classification were briefly mentioned and different points of view on virus names were commented on, and exemplified by 12 different proposals for the name of tobacco mosaic tobamovirus. The history and activities of the International Committee on Taxonomy of Viruses were briefly reviewed, stressing its legislation and regulation efforts. In the main part of the lecture current regulations and proposals of ICTV were presented concerning introduction of species concept and species-genus-family-order system of virus taxonomy, as well as creating a single taxonomy system for all the viruses. The main results of some research works in the field of genetics and molecular biology were reviewed forming the basis for understanding genetic diversification and speciation in plant viruses by comparing a gene structure and expression mechanisms. The proposed species names as well as those of genus, family and order are cited. Finally, current trends in virus taxonomy were presented. The implications of so-called "super-groups" and some additional proposals for new virus orders and families were discussed. The situation in the taxonomy of plant viroids was briefly commented on.