A. Bermpohl et al., EXOPOLYSACCHARIDES IN THE PATHOGENIC INTERACTION OF CLAVIBACTER-MICHIGANENSIS SUBSP MICHIGANENSIS WITH TOMATO PLANTS, Microbiological research, 151(4), 1996, pp. 391-399
The extracellular polysaccharide (EPS) of seven strains of Clavibacter
michiganensis subsp. michiganensis, a pathogen of tomato (Lycopersico
n esculentum Mill.) was isolated and the carbohydrate composition was
determined. Based on the EPS analyses and the interaction with tomato
plants the strains could be placed into two groups. Strains of Group I
efficiently colonize tomato plants and produce an EPS with an identic
al carbohydrate composition with fucose, glucose, galactose in a molar
ratio of 2 : 1 : 1. When injected into leaves of four-o'clock (Mirabi
lis jalapa L.), a non host plant of C. m. subsp. michiganensis, strain
s of Group I induce a hypersensitive-like reaction (HR). In contrast,
isolates of Group II are avirulent, do not propagate in tomato and fai
led to induce an HR on M. jalapa. These strains produced only small am
ounts of EPS in vitro which was distinctly different in composition. A
lthough the composition of the EPS in planta was not definitively dete
rmined, wilting, the typical disease symptom of tomato caused by C. m.
subsp. michiganensis, seems not to depend on EPS production based on
two lines of evidence. First, EPS(-) mutants were not altered in virul
ence, and second, the natural isolate NCPPB 1574 (Group I) and the pla
smid-free cured derivative of NCPPB382, CMM100, did not cause disease
although they produced EPS in identical quantities and composition as
the virulent strains and effectively colonized tomato plants.