First Report of Common Scab on Potato Caused by Streptomyces europaeiscabiei in Taiwan

Abstract

HomePlant DiseaseVol. 102, No. 4First Report of Common Scab on Potato Caused by Streptomyces europaeiscabiei in Taiwan PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Common Scab on Potato Caused by Streptomyces europaeiscabiei in TaiwanC. Y. Lin, H. F. Ni, and C. W. HuangC. Y. Lin†Corresponding author: C. Y. Lin; E-mail: E-mail Address: eris2024@dns.caes.gov.twSearch for more papers by this author, H. F. NiSearch for more papers by this author, and C. W. HuangSearch for more papers by this authorAffiliationsAuthors and Affiliations C. Y. Lin † H. F. Ni C. W. Huang , Department of Plant Protection, Chiayi Agricultural Experiment Branch, Agricultural Research Institute, Chiayi 60014, Taiwan. Published Online:12 Feb 2018https://doi.org/10.1094/PDIS-05-17-0667-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Common scab caused by Streptomyces spp. is an economically important disease of potato (Solanum tuberosum L.) worldwide. In Taiwan, only Streptomyces scabies has been reported as the causal species of common scab on potato tubers. In spring of 2015 and 2016, potato tubers of cv. Kennebec with scab symptoms were collected from 14 fields in Taichung, Yunlin County, and Chiayi County. Bacteria were isolated from scab lesions using International Streptomyces Project (ISP) medium 4. Colonies with white to gray spores were transferred to a new ISP medium 4 after 7 days. Pure cultures of isolates were obtained by transferring single colonies three times. Genomic DNA of pure culture bacteria was extracted by an NaOH-based method (Wang et al. 1993) and used as template for PCR with species-specific primers for 16S rRNA gene sequences of S. scabies, S. turgidiscabiei, and S. acidiscabiei (Leiminger et al. 2013). Of the 33 bacterial isolates recovered, 31 isolates had amplified segments of S. scabies and two remained unidentified. Because 16S rRNA gene sequences in S. scabies and S. europaeiscabiei are nearly identical, distinguishing the species requires exploitation of an Hpy99I endonuclease restriction site in the 16S-23S rRNA ITS region of S. scabies (Flores-González et al. 2008). Among the 31 Streptomyces spp. isolates tested, one isolate could not be cleaved with Hpy99I and consequently was identified as S. europaeiscabiei. To further confirm the identity of the isolate, sequences of atpD, recA, and ropB genes (GenBank accession nos. KX981452, KX981453, and KX981454) from the isolate were found to be 99.4, 100, and 99.9% identical, respectively, to corresponding S. europaeiscabiei type strain IBSBF 2023 (JF303745) and S. europaeiscabiei strain 364 (KJ802472 and KJ802473) sequences (Hiltunen et al. 2014). Pathogenicity of the S. europaeiscabiei isolate was confirmed using a radish seedling assay (Flores-González et al. 2008). The radish seedlings grown with the S. europaeiscabiei isolate showed reduced growth and hypertrophy compared with seedlings grown on oat meal agar without bacteria. In addition, potato seedlings (cv. Kennebec) (three pots per treatment) was inoculated with a spore suspension (106 CFU/ml) of the S. europaeiscabiei isolate. Six weeks later, potato tubers were harvested and evaluated for scab symptoms. The experiment was done twice. Potato tubers from the plants inoculated with S. europaeiscabiei isolate exhibited superficial, raised, or pitted scab symptoms, whereas no symptoms were observed on tubers from the noninoculated potato plants. The pathogen was reisolated from the lesions and confirmed identical to the original isolate by PCR and Hpy99I digestion. To our knowledge, this is the first report of S. europaeiscabiei causing potato common scab in Taiwan.