VIEW ARTICLE

Spiroplasma: Motile, Helical Microorganism Associated with Corn Stunt Disease. Robert E. Davis, ARS, USDA, Beltsville, Maryland 20705; Joseph F. Worley, ARS, USDA, Beltsville, Maryland 20705. Phytopathology 63:403-408. Accepted for publication 10 October 1972. DOI: 10.1094/Phyto-63-403.

Helical morphology and contractile movements of filaments produced by the organism associated with corn stunt disease distinguish it from described species of mycoplasmas. The filaments are 0.2 to 0.25 µ by 3 to ca. 15 µ, usually with regular wave (gyre) length and amplitude in a given coil, rarely loosely or irregularly coiled, and often with spherical bodies (0.4 to 0.6 µ in diam) attached. Three-dimensionality of the filament helix was observed by phase contrast light microscopy and by stereo electron microscopy. Size and apparent lack of cell wall, axial fibrils, flagellar structure, and envelope suggest affinities with mycoplasmas, but in juice expressed from infected plants, the filaments whirled or spun rapidly about the long axis of the helix and exhibited flexional (flexing, bending, and curling) motions reminiscent of movements by some spirochaetes. In order to reflect important differences from previously described species, we propose use of the trivial term spiroplasma for the organism, until sufficient data are available to assign the organism a Latin binomial and a taxonomic position.