Effects of concanamycins produced by Streptomyces scabies on lesion type of common scab of potato

Streptomyces scabies , causative agent of common scab of potato, produces the phytotoxins concanamycin and thaxtomin. In a potato tuber slice assay to study the contribution of concanamycins to lesion development, concanamycin A had weak necrosis-inducing activities; >10× the amount of thaxtomin A was needed to produce equivalent lesion severity. Concanamycins were detected in tubers inoculated with S. scabies , which caused deep-pitted lesions but not in those inoculated with Streptomyces acidiscabies , which caused corky, raised lesions. In field-grown, diseased potatoes, concanamycin content tended to be higher in tubers with deep-pitted lesions than in those with corky, raised lesions.