First report of Streptomyces bottropensis causing potato common scab in Hebei Province, China.
Potato common scab (PCS) is caused by phylogenetically diverse Streptomyces spp. To identify new pathogens, potato tubers (Solanum tuberosum cv. Favorita) with scab symptoms were collected from fields in Hebei Province (China) in November 2014. An isolate was obtained by transferring single colonies and incubation at 28°C on Streptomyces selective medium. Morphological, cultural, physiological, and biochemical characteristics suggested that the isolate belongs to the genus Streptomyces. BLAST analysis of the sequences of its 16S rRNA amplicon against the NCBI GenBank database determined that the isolate was highly related to Streptomyces bottropensis type strain ATCC25435 (∼100%), and it was designated as S. bottropensis AR (ACCC1953). The isolate gave a positive PCR reaction with primers BottF and BottR for S. bottropensis. PCR amplification and sequencing revealed that all three pathogenicity-related genes involved in PCS were found in this isolate, with high similarity (99 to 100%) with those in Streptomyces scabies ATCC49173 (txtAB, EU864252; nec1, AM253591; and tomA, FJ007481). However, these genes were not detected in the type strain of S. bottropensis. This is thought to be the first report of S. bottropensis causing PCS; other formal reports include Streptomyces turgidiscabiei, S. acidiscabiei and S. galilaeus in China. Pathogenicity of Streptomyces spp. may be transferred through horizontal gene transfer of pathogenicity genes, and may explain the emergence of new pathogenic S. bottropensis in China.