Abstract

Spiroplasma strains from plant and arthropod hosts, and from surfaces of flowers, were classified into three serological groups (designated I, II, and III) based on results from growth-inhibition tests. No significant cross reactions were observed among groups. The groupings were confirmed by ring-interface precipitin and microprecipitin tests, using membrane preparations as test antigens, and by organism-deformation tests. Serogroup I contained three subgroups: subgroup A (Spiroplasma citri strains Maroc R8A2 and C189), subgroup B (strain AS 576 and closely related strains from honeybee or flowers), and subgroup C (corn stunt spiroplasma strains). Serogroup II contained strains 23-6 and 27-31 isolated from flowers of the tulip tree (Liriodendron tulipifera L.) growing in Maryland. Serogroup III contained strains SR 3 and SR 9 isolated from flowers of the tulip growing in Connecticut. The subgroups of serogroup I were based on organism deformation, microprecipitin, and ring-interface precipitin tests. The data are consistent with the hypothesis that the three serogroups represent no less than three distinct spiroplasma species.