Criteria for phytoplasma 16Sr group/subgroup delineation and the need of a platform for proper registration of new groups and subgroups.

As phytoplasmas are discovered at an ever-increasing pace in emerging and re-emerging plant diseases worldwide, the scheme for classification of phytoplasmas into 16S rRNA gene RFLP (16Sr) groups and subgroups is experiencing an ongoing rapid expansion. Improper delineation or designation of new groups and subgroups can open potential conflicts in classifying newly identified phytoplasma strains. To maintain the integrity of the classification scheme, criteria for the delineation of new groups and subgroups must be followed, and proper registration should be required to track established groups and subgroups.