Spiroplasma kunkelii sp. nov.: Characterization of the Etiological Agent of Corn Stunt Disease

Abstract

Nine strains of spiroplasma subgroup 1-3, which comprise the etiological agent of corn stunt disease, were similar in their serological properties. Strain E275T (T = type strain) was studied by using criteria proposed by the International Committee on Systematic Bacteriology Subcommittee on Taxonomy of Mollicutes for descriptions of new mollicute species. This strain was shown to belong to the class Mollicutes by the ultrastructure of its limiting membrane, its procaryotic organization, its colonial morphology, and its filtration behavior and to the family Spiroplasmataceue by its helical morphology and motility. Although some serological cross-reactions with other group I spiroplasma strains was observed, strain E275T could be readily distinguished from representatives of other group I subgroups. Subgroup 1-3 spiroplasmas and other group I strains also differed in their one-and two-dimensional polyacrylamide gel protein patterns, plant and insect host ranges, and pathogenicities. Growth in M1A or M1D medium occurred at 20 to 3OOC. Cholesterol was required for growth. Glucose was fermented, and arginine was catabolized. Subgroup 1-3 strains, including strain E275T, reacted with considerable homogeneity in deformation tests and were completely separable from strains belonging to subgroup 1-1 (Spiroplasma citri) and subgroup 1-2 (Spiroplusmu melliferum). Strain E275T was also serologically distinct from subgroups 1-4 through 1-8, Spiroplasmu floricolu (group 111), Spiroplusmu apis (group IV), Spiroplusmu mirum (group V), and representative strains of spiroplasma groups I1 and VI through XI. The deoxyribonucleic acid of strain E275T hybridized with the deoxyribonucleic acid of S . citri at significant levels (33 to 68%, depending on the technique used). These results demonstrate that strain E275T and similar strains meet the criteria proposed by the International Committee on Systematic Bacteriology Subcommittee for elevation of spiroplasma subgroups to species. We propose that such strains be named Spiroplasma kunkelii. Strain E275T has been deposited in the American Type Culture Collection as strain ATCC 29320T.Corn stunt disease was first reported as a stunting and striping syndrome of maize in Texas (2). Although this disease was studied biologically (53,54,65,66), the procaryotic nature of the etiological agent remained unsuspected until the late 1960s. Then, prompted by reports that certain leafhopper-borne plant diseases thought to be of viral etiology were in fact caused by wall-less procaryotes, R. R. Granados and colleagues demonstrated that wall-less procaryotes were associated with "Louisiana corn stunt disease" in plant and insect vectors (43,44). These organisms could also be demonstrated in negatively stained preparations of sap from diseased corn (43). Following these morphological studies, Chen and Granados (13) achieved long-term maintenance of the Rio Grande strain of the corn stunt agent in cell-free media and observed filaments similar to those seen in vivo. Subsequently, phase-contrast microsc...

Revised Group Classification of the Genus Spiroplasma (Class Mollicutes), with Proposed New Groups XII to XXIII

“…Disk growth inhibition tests were carried out as previously noted (30, 32). Procedures for the metabolism inhibition and deformation tests have also been described earlier (29,31,33,34).…”

“…mirum [24], respectively). In addition, following recommendations by the International Committee on Systematic Bacteriology Subcommittee on the Taxonomy of Mollicutes (15) for elevation of group I subgroups to species levels, we recently characterized representatives of subgroups I-2,1-3, and 1-8 as Spiroplasma melliferum (9), Spiroplasma kunkelii (29), and Spiroplasma phoeniceum (20), respectively.…”

Spiroplasma phoeniceum sp. nov., a New Plant-Pathogenic Species from Syria

“…Hyperimmune antiserum was prepared against strain P40T as described previously (69). Disk growth inhibition tests (17, 63) were performed with spiroplasmas grown in M1D medium (60). Antigens grown in broth were usually diluted to about lo5 color-changing units per ml.…”

“…We propose that such strains be named Spiroplasma phoeniceum. Strain P40T has been deposited 'in the American Type Culture Collection (= ATCC 43115T) Although many Spiroplasma species have been isolated during the last 10 years from insects and plants, only twoSpiroplasma citri (47), the etiological agent of citrus stubborn disease (38), and S. kunkelii (60), the spiroplasma that causes corn stunt disease (11, 68) -ar e plant pathogenic. Citrus stubborn disease is widespread in the Mediterranean region as a result of the natural dissemination of S. citri by leafhoppers (2,24).…”

Characterizing the replication and stability regions of Spiroplasma citri plasmids identifies a novel replication protein and expands the genetic toolbox for plant-pathogenic spiroplasmas

“…Three spiroplasma species, Spiroplasma citri (Saglio et al, 1973), Spiroplasma kunkelii (Whitcomb et al, 1986) and Spiroplasma phoeniceum (Saillard et al, 1987), have been associated with plant diseases. S. citri is the aetiological agent of the citrus stubborn and horseradish brittle root diseases and was the first plant mollicute to be cultured in vitro (Fletcher et al, 1981;Saglio et al, 1971).…”