HomePlant DiseaseVol. 102, No. 10First Report of Dickeya dianthicola in Potatoes in Australia PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Dickeya dianthicola in Potatoes in AustraliaD. Wright, A. Bwye, M. Banovic, J. Baulch, C. Wang, S. Hair, N. Hammond, B. Coutts, and M. KehoeD. Wright†Corresponding author: D. Wright; E-mail: E-mail Address: dominie.wright@dpird.wa.gov.auhttp://orcid.org/0000-0002-0360-8201Search for more papers by this author, A. BwyeSearch for more papers by this author, M. BanovicSearch for more papers by this author, J. BaulchSearch for more papers by this author, C. WangSearch for more papers by this author, S. HairSearch for more papers by this author, N. HammondSearch for more papers by this author, B. CouttsSearch for more papers by this author, and M. KehoeSearch for more papers by this authorAffiliationsAuthors and Affiliations D. Wright † A. Bwye M. Banovic J. Baulch C. Wang S. Hair N. Hammond B. Coutts M. Kehoe , DPIRD Diagnostic Laboratory Services, Department of Primary Industries and Regional Development, Western Australia. Published Online:13 Aug 2018https://doi.org/10.1094/PDIS-01-18-0094-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Blackleg of potatoes caused by the bacterium Pectobacterium carotovorum subsp. carotovorum occurs sporadically in potato (Solanum tuberosum) crops in Western Australia (Taylor 2017). In May 2017, plants from a seed potato crop growing in southwest Western Australia were submitted to the DPIRD Diagnostic Laboratory Services with symptoms similar to blackleg. The plants had collapsed in the field, and the stems were brown-black, dry, and hollow. In some cases, where the stems were not hollow there was distinct vascular discoloration present. Small tubers attached to the mother plants were soft. Bacteria were isolated from plant and tuber material by suspending 1 cm of vascular tissue in sterile distilled water for 30 min before streaking onto nutrient agar and sucrose peptone agar (SPA). Individual colonies were selected and restreaked onto SPA and grown for 24 h before doing standard biochemical tests including gram stain and 3% KOH. The bacterium Dickeya dianthicola was identified by using matrix assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry (Brucker) with a score value of 2.147 and 2.114. The bacterial isolates were subject to nucleotide sequence analysis using the primers described by Suharjo et al. (2014). Partial recA sequences were amplified using primers ErecA1/ErecA2 (Suharjo et al. 2014). The resulting polymerase chain reaction products were sequenced and analyzed using Geneious version 10 (Biomatters) and BLASTn (Altschul et al. 1990). The final sequences were submitted to GenBank with the accession numbers MG717687, MG7177688, MG717689, and MG717690. All of the above sequences shared 100% nucleotide identity with each other, and their closest match using a BLASTn search was D. dianthicola (CP017638). Koch’s postulates were completed on potato plants that had been grown for 6 weeks in a glasshouse. Plants were then removed from the glasshouse and placed into a controlled temperature cabinet, which was maintained at 28 to 30°C during the day and 22 to 24°C at night. Once the stems had reached a height of 20 cm, 5 µl of bacterial suspension at 106 CFU/ml was injected into the stem of each plant, three nodes above the base. Five varieties were used; Evolution, Daifea, Jester, Volare, and Lorely. For each variety, four plants were stab inoculated with D. dianthicola, one plant with P. carotovorum, and one plant with sterile distilled water as the negative control. Plants were watered daily. Plants inoculated with D. dianthicola started to collapse within 3 days of inoculation and stems were blackening, whereas those inoculated with P. carotovorum took 7 days before wilting symptoms and discoloration of the stems were observed. Bacteria were isolated from lesions on the individual plants and were then confirmed to be D. dianthicola or P. carotovorum using MALDI-TOF. All varieties were susceptible to the D. dianthicola isolate used. No symptoms were observed on control plants. These results from biological and molecular testing confirm the identification of the pathogen D. dianthicola being detected in Australia for the first time. Potato growers will need to use management strategies and phytosanitary measures to avoid the further spread of D. dianthicola to new crops and to maintain healthy seed stocks.