Clavibacter: a New Genus Containing Some Phytopathogenic Coryneform Bacteria, Including Clavibacter xyli subsp. xyli sp. nov., subsp. nov. and Clavibacter xyli subsp. cynodontis subsp. nov., Pathogens That Cause Ratoon Stunting Disease of Sugarcane and Bermudagrass Stunting Disease
Date of this Version
Int J Syst Bacteriol April 1984 34:107-117; doi:10.1099/00207713-34-2-107
A total of 23 strains of coryneform bacteria that cause ratoon stunting disease of sugarcane and Bermudagrass stunting disease were examined. These included 17 sugarcane strains from Florida, Louisiana, South Africa, Brazil, and Japan and six Bermudagrass strains from Florida and Taiwan. The sugarcane and Bermudagrass strains contained 2,4-diaminobutyric acid, rhamnose, and fucose in their cell walls, suggesting a relationship to some other phytopathogenic coryneform bacteria and related organisms with similar cell wall compositions. The cellular protein patterns of the sugarcane and Bermudagrass strains after polyacrylamide gel electrophoresis resembled the patterns of Corynebacterium michiganense subspecies more than the patterns of some other diaminobutyric acid-containing taxa. The protein patterns of the sugarcane strains were distinct from the patterns of the Bermudagrass strains examined. The guanine-plus-cytosine contents of the deoxyribonucleic acids of two sugarcane strains and one Bermudagrass strain were 66 mol%. The sugarcane and Bermudagrass strains formed a homogeneous group based on morphological characteristics and most biochemical characteristics. All of the sugarcane strains were nonpigmented (white) and grew more slowly in culture than the yellow-pigmented Bermudagrass strains. The Bermudagrass strains, unlike the sugarcane strains, hydrolyzed starch and utilized citrate and malate. Although the phytopathogenic coryneform bacteria with 2,4-diaminobutyric acid in the peptidoglycans of their cell walls are presently classified in the genus Corynebacterium, recent studies have indicated that these phytopathogens should be reclassified. These bacteria form a distinct group with characteristics different from those of all existing genera as presently circumscribed; therefore, we propose that a new genus, Clavibacter, be established for these and similar bacteria. We propose reclassification of Corynebacterium michiganense (including Corynebacterium michiganense subsp. michiganense, Corynebacterium michiganense subsp. insidiosum, Corynebacterium michiganense subsp. sepedonicum, Corynebacterium michiganense subsp. nebraskense, and Corynebacterium michiganense subsp. tessellarius), Corynebacterium iranicum, Corynebacterium tritici, and Corynebacterium rathayi in the new genus Clavibacter. We further propose that Clavibacter xyli be recognized as a new species with the following subspecies: Clavibacter xyli subsp. xyli sp. nov., subsp. nov., the species and subspecies type strain of which is sugarcane strain L1A (= ATCC 33974 = NCPPB 3152 = PDDC 7127), and Clavibacter xyli subsp. cynodontis subsp. nov., the subspecies type strain of which is Bermudagrass strain TB1A (= ATCC 33973).