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During a survey of Streptomyces infecting potato (Solanum tuberosum) in the UK, two strains were isolated which were distinct from S. scabiei, which is already known to occur in the UK. Amplification with species-specific PCR primers (Wanner, 2006) identified these strains as S. turgidiscabies (Miyajima et al., 1998) and S. acidiscabies (Lambert & Loria, 1989), and the same PCR assay indicated presence of these species in several fields in England and Scotland. Representative strains were deposited in the UK National Collection of Plant Pathogenic Bacteria as NCPPB4444 and NCPPB4445 respectively. Strain NCPPB4444 was isolated from cv. Desiree tubers, grown in South Yorkshire, England, with large erumpent lesions. A majority of tubers from the same seed stock in the same field exhibited similar symptoms. Strain NCPPB4445 was isolated from cv. Maris Piper, grown in Aberdeenshire, Scotland, on soil of pH 5·4, where disease incidence was high and dry flaky scab symptoms typically covered almost 100% of the tuber surface. Both strains were isolated on NPPC medium (Schaad et al., 2001), producing small white sporulating colonies.

Inoculation of radish seedlings with both strains resulted in severe necrosis within 2 weeks. Potato minitubers (cv. Maris Piper) grown in pots containing sterilized compost were inoculated with 250 mL suspensions of Streptomyces (approx. 107 cfu mL−1) when leaves first emerged. After 12 weeks, lesions were observed on tubers in each of five replicate pots. Uninoculated controls were free from symptoms. Bacteria recovered from lesions were confirmed by PCR to be the same species as the inocula. To confirm species identity, a portion of the 16S rDNA of each original strain was sequenced. The sequence from strain NCPPB4444 (GenBank Accession No. FJ817424) was 100% identical to that of S. turgidiscabies type strain ATCC700248. The sequence from strain NCPPB4445 (FJ804480) was 100% identical to that of the S. acidiscabies type strain ATCC49003. Although several Streptomyces spp. are known to cause common scab of potato, the species identity is of significance as different diagnosis and control methods may apply. This is the first report in the UK of common scab of potato caused by S. turgidiscabies or S. acidiscabies.

Acknowledgements

  1. Top of page
  2. Acknowledgements
  3. References

This work was funded by a Defra Sustainable Arable LINK grant (LK0989) with financial support from Potato Council Ltd.

References

  1. Top of page
  2. Acknowledgements
  3. References
  • Lambert DH, Loria R, 1989. Streptomyces acidiscabies sp. nov. International Journal of Systematic Bacteriology 39, 3936.
  • Miyajima K, Tanaka F, Takeuchi T, Kuninaga S, 1998. Streptomyces turgidiscabies sp. nov. International Journal of Systematic Bacteriology 48, 495502.
  • Schaad NW, Jones JB, Chun W, 2001. Laboratory Guide for Identification of Plant Pathogenic Bacteria, 3rd edn. St Paul, MN, USA: APS Press.
  • Wanner L, 2006. A survey of genetic variation in Streptomyces isolates causing potato common scab in the United States. Phytopathology 96, 136371.