Streptomyces species isolated from potato scabs in France: numerical analysis of "Biotype-100" carbon source assimilation data.

Thirty one strains of Streptomyces isolated from common and netted scabs in France were characterized using "Biotype-100" strips and 14 conventional tests. Numerical analysis showed that S. scabiei was the single causal agent of common scab in France. However the strains clustered among S. scabiei were phenotypically heterogeneous, since 3 subphenons were delineated. The strains clustered in subphenons 1a and 1c and one strain of subphenon 1b were associated with common scab. On the other hand, a group of strains clustered in phenon 2, distinct from S. scabiei, S. acidiscabies and S. caviscabies, was often associated with symptoms of netted scab. None of the French strains thus far pathogenic to potato belonged to the already described species S. acidiscabies and S. caviscabies from Japan and North America. Phenotypic characteristics clearly differentiated all the various groups of strains described.