Pathogenicity by the plant pathogenic Streptomyces scabies, the causative agent of common scab disease, on various economically important root and tuber crops is triggered by cellobiose, a subunit of plant cell wall polymer cellulose. Cellobiose induces production of thaxtomin A, the main virulence factor of this species. This phytotoxin affects cellulose synthase leading to stunted growth and tissue necrosis. The ABC transporter CebEFG-MsiK has been shown to be the primary importer of cellobiose, hence, a deletion of this transporter showed a significant decrease in thaxtomin production and a consequent attenuated virulence on plants. However, bacteria missing this transporter were still viable on minimal medium with cellobiose as the only carbon source (TDMc). Homology searches revealed there to be two other transporter candidates. Of these, the transporter with the highest homology seems to be absent in other pathogens but is found in a select group of non-pathogenic Streptomyces species, while a third transporter is located within the pathogenicity island of the pathogenic species. Mutants in the genes coding for these transporters showed, under the conditions tested, at least one other transporter is important during the pathogenic interaction with the plant host. Under more complex conditions, as would be in plant-microbe interactions, the loss of this transporter could not be compensated for by the first transporter as shown by the results of plant bioassays and the inability of this mutant to produce toxin on plant-based media known to induce thaxtomin production.