Streptomyces scabiei

Streptomyces scabiei (also wrongly named Streptomyces scabies) is a streptomycete bacterium species found in soils around the world. Unlike most of the 500 or so Streptomyces species it is a plant pathogen causing corky lesions to form on tuber and root crops as well as decreasing the growth of seedlings. Along with other closely related species it causes the potato disease common scab, which is an economically important disease in many potato growing areas. It was first described in 1892, being classified as a fungus, before being renamed in 1914 and again in 1948. Several other species of Streptomyces cause similar diseases to S. scabiei but other, more closely related species, do not.

The genome of S. scabiei has been sequenced and is the largest Streptomyces genome known so far. The genome contains a pathogenicity island containing the genes required for S. scabiei to infect plants, and which can be transferred between different species. S. scabiei can produce several related toxins which are the most responsible for its pathogenicity, but several other systems have also been identified which contribute. It can infect young seedlings of all plants, as well as mature root and tuber crops, but is most often associated with causing common scab of potato.