First Report of Bacterial Leaf Spot of Red Maple Caused by Pseudomonas syringae pv. syringae in Tennessee

HomePlant DiseaseVol. 107, No. 8First Report of Bacterial Leaf Spot of Red Maple Caused by Pseudomonas syringae pv. syringae in Tennessee PreviousNext DISEASE NOTE OPENOpen Access licenseFirst Report of Bacterial Leaf Spot of Red Maple Caused by Pseudomonas syringae pv. syringae in TennesseeMadhav Parajuli, Cansu Oksel, Farhat A. Avin, Prabha Liyanapathiranage, and Fulya Baysal-GurelMadhav Parajulihttps://orcid.org/0000-0002-5810-5337Department of Agricultural and Environmental Sciences, Tennessee State University, Otis L. Floyd Nursery Research Center, McMinnville, TN 37110Search for more papers by this author, Cansu OkselDepartment of Agricultural and Environmental Sciences, Tennessee State University, Otis L. Floyd Nursery Research Center, McMinnville, TN 37110Search for more papers by this author, Farhat A. Avinhttps://orcid.org/0000-0002-4323-1058Department of Agricultural and Environmental Sciences, Tennessee State University, Otis L. Floyd Nursery Research Center, McMinnville, TN 37110Search for more papers by this author, Prabha LiyanapathiranageDepartment of Agricultural and Environmental Sciences, Tennessee State University, Otis L. Floyd Nursery Research Center, McMinnville, TN 37110Search for more papers by this author, and Fulya Baysal-Gurel†Corresponding author: F. Baysal-Gurel; E-mail Address: [email protected]https://orcid.org/0000-0001-9920-9880Department of Agricultural and Environmental Sciences, Tennessee State University, Otis L. Floyd Nursery Research Center, McMinnville, TN 37110Search for more papers by this authorAffiliationsAuthors and Affiliations Madhav Parajuli Cansu Oksel Farhat A. Avin Prabha Liyanapathiranage Fulya Baysal-Gurel † Department of Agricultural and Environmental Sciences, Tennessee State University, Otis L. Floyd Nursery Research Center, McMinnville, TN 37110 Published Online:14 Aug 2023https://doi.org/10.1094/PDIS-12-22-2880-PDNAboutSectionsView articlePDFSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat View articleRed maple (Acer rubrum L.) is an economically important ornamental nursery plant grown for its aesthetic value. In May 2022, field- and container-grown red maple ‘October Glory’ plants exhibited severe leaf spots in a commercial nursery in Warren County, Tennessee. Leaf spots were brown-to-black color with a yellow halo. Disease severity was about 40% of leaf area, and incidence was 60 to 70% of 10,000 plants. Symptomatic leaf tissues were surface sterilized with 0.525% sodium hypochlorite for 1 min and washed twice with sterilized water. Bacterial colonies, cream colored and circular with smooth margins, were obtained on King’s B (KB) and nutrient agar media after 3 days of incubation at 28°C. Bacteria were gram-negative and fluorescent on KB under UV light. The biochemical and physiological test results were negative for cytochrome C oxidase, pectolytic activity on potato slices, and arginine dihydrolase, but positive for gelatin liquefaction, esculin hydrolysis, and levan production. The BIOLOG test was positive for the utilization of D-galactose, D-galacturonic acid, D-galactonic acid γ-lactone, and D-gluconic acid and was negative for the utilization of β-methyl-D-glucoside, N-acetyl-D-glucosamine, α-hydroxybutyric acid, D-glucose-6-phosphate, α-keto-butyric acid, and α-ketoglutaric acid. To confirm the bacterial identity, total genomic DNA was extracted using a DNeasy PowerLyzer Microbial Kit directly from pure cultures (strains FBG1662 and FBG4230). The small subunit ribosomal RNA (16S rRNA), RNA polymerase sigma factor (rpoDp and rpoDs), citrate synthase (gltA), and DNA gyrase (gyrB) genes were amplified and sequenced by the primers 8F/1492R (Galkiewicz and Kellogg 2008), rpoDpF/R, rpoDsF/R, gltAF/R, and gyrBF/R (Sarkar and Guttman 2004), respectively. The sequences of the two strains (GenBank accession nos.: 16S, OP962145 and OP948281; rpoDp, OP998258 and OP957300; rpoDs, OP998259 and OP957299: gltA, OP998256 and OP957301; gyrB, OP998257 and OP957302) were >99% similar (100% coverage) to the complete genome of Pseudomonas syringae pv. syringae (CP026568) in the NCBI database. A phylogenetic analysis was performed, and it confirmed the identity using concatenated sequences of gltA, gyrB, rpoDp, rpoDs, and 16S of P. syringae pv. syringae and other closely related taxa retrieved from GenBank. Based on morphological and molecular identification, both bacterial strains were identified as P. syringae pv. syringae. The pathogenicity test was conducted by spray inoculation of ten 1-year-old red maple ‘October Glory’ plants with bacterial suspension (107 CFU/ml) using the bacterial strain FBG4230. Ten plants were sprayed with sterilized water as a control. All plants were covered with clear plastic for 24 h and incubated in a greenhouse at 21 to 23°C, 70% relative humidity, and a 16-h photoperiod. Seven days after inoculation, brown-to-black leaf spots surrounded by a yellow halo developed on all inoculated plants, whereas the control plants remained symptomless. The bacterium was reisolated from the inoculated plants, and it was found to be 100% identical to P. syringae pv. syringae using biochemical tests as well as sequence analysis. P. syringae has been reported pathogenic in red maple, causing leaf spot in Oregon (Malvick and Moore 1988). To our knowledge, this is the first report of bacterial leaf spot caused by P. syringae pv. syringae in red maple in Tennessee. Identification of this bacterial pathogen on red maple is crucial in developing timely management practices.The author(s) declare no conflict of interest.References:Galkiewicz, J. P., and Kellogg, C. A. 2008. Appl. Environ. Microbiol. 74:7828. https://doi.org/10.1128/AEM.01303-08 Crossref, ISI, Google ScholarMalvick, D. K., and Moore, L. W. 1988. Phytopathology 78:1366. https://doi.org/10.1094/phyto-78-1366 Crossref, ISI, Google ScholarSarkar, S. F., and Guttman, D. S. 2004. Appl. Environ. Microbiol. 70:1999. https://doi.org/10.1128/AEM.70.4.1999-2012.2004 Crossref, ISI, Google ScholarThe author(s) declare no conflict of interest.DetailsFiguresLiterature CitedRelated Vol. 107, No. 8 August 2023SubscribeISSN:0191-2917e-ISSN:1943-7692 Download Metrics Article History Issue Date: 29 Aug 2023Published: 14 Aug 2023First Look: 12 Feb 2023Accepted: 5 Feb 2023 Page: 2515 Information© 2023 The American Phytopathological SocietyKeywordsbacterial leaf spotPseudomonas syringae pv. syringaered mapleThe author(s) declare no conflict of interest.PDF download