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First Report of Powdery Mildew Caused by Erysiphe alphitoides on Euonymus japonica in Korea

2016; American Phytopathological Society; Volume: 101; Issue: 2 Linguagem: Inglês

10.1094/pdis-08-16-1128-pdn

1943-7692

H. B. Lee, Thuong T. T. Nguyen,

Plant Pathogens and Fungal Diseases

HomePlant DiseaseVol. 101, No. 2First Report of Powdery Mildew Caused by Erysiphe alphitoides on Euonymus japonica in Korea PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Powdery Mildew Caused by Erysiphe alphitoides on Euonymus japonica in KoreaH. B. Lee and T. T. T. NguyenH. B. LeeSearch for more papers by this author and T. T. T. NguyenSearch for more papers by this authorAffiliationsAuthors and Affiliations H. B. Lee T. T. T. Nguyen , Division of Food Technology, Biotechnology & Agrochemistry, College of Agriculture & Life Sciences, Chonnam National University, Gwangju 61186, Korea. Published Online:16 Nov 2016https://doi.org/10.1094/PDIS-08-16-1128-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Euonymus japonica, family Celastraceae, is an evergreen shrub native to Korea, China, and Japan that is often used as an ornamental hedge plant. In October 2014, powdery mildew symptoms and signs were observed amphigenously on the leaves of E. japonica in a park in Seoul, Korea. Also, in June 2016, the same symptoms were found on E. japonica plants in a garden in Gwangju (35°10′N, 126°55′E), Korea, showing higher incidence and severity. Diseased leaves showed white colonies, associated with brown spots on the surface due to the presence of a hyperparasite, Ampelomyces quisqualis, and heavily infected young leaves. Voucher specimens were deposited at Environmental Microbiology Laboratory Fungarium, Chonnam National University, Gwangju, Korea, as EML-EJP1, EML-EJP2, and EML-EJP3. Appressoria of the fungus were lobed, and solitary or in opposite pairs. Measurements were made of 20 conidiophores and 50 conidia. Conidiophores were cylindrical, 45.0 to 77.0 × 6.5 to 10.5 μm. Foot cells of the conidiophores were straight to substraight to cylindrical, and followed by 1 to 3 shorter cells. Conidia were formed singly, cylindrical or ellipsoid-cylindrical, and measured 26.5 (–36.5) to 45 × 12 to 18.5 μm with a L/W ratio of 1.8 to 3.3. Short to moderately long germ tubes were produced terminating in lobed appressoria. The teleomorph was not found. Morphological characters were consistent with anamorphic Erysiphe species. To identify the fungus at the species level, mycelia and conidia of four samples from Euonymus japonica were collected with a sterile needle under a stereomicroscope. rDNA was extracted from mycelia and conidia using the Higene Genomic DNA Prep Kit for fungi (Biopact Corp., Korea). The internal transcribed spacers (ITS1 and ITS2) and 5.8S gene was amplified using primers ITS1F (5′-CTTGGTCATTTAGAGGAAGT-3′) and LR5F (5′-GCTATCCTGAGGGAAAC-3′) as by Lee (2013). A BLASTn search of the rDNA ITS sequences in GenBank indicated that EML-EJP1 (KP325487), EJP2 (KX495611), and EJP3 (KX495610) matched 100% (608/608 bp), 99.6% (766/769 bp), and 99.8% (497/498 bp) with Erysiphe alphitoides (Griffon & Maubl.) Braun & Takam (EF672350, AB257430, and AB292700, respectively). Phylogenetic analysis showed that our strains, EML-EJP1, EJP2, and EJP3, were placed within Alphitoides clade comprising E. alphitoides, E. akebiae, E. menispermi var. dahurica, E. wallrothii, E. sinomenii, and E. euonymicola. Interestingly, when the ITS sequences of our strain and some E. alphitoides were compared with E. euonymicola as a subclade within the Alphitoides clade, there was one base difference between them. The morphological characteristics of our strain completely matched E. alphitoides described by Takamatsu et al. (2007), except for a slight difference in width. The pathogenicity was confirmed by gently pressing the infected leaves onto five leaves of 5-year-old E. japonica plants. Five leaves were inoculated on each plant. The inoculated and noninoculated plants were maintained at 23 ± 2°C with a 12-h photoperiod and 80 to 85% RH. Ten days after inoculation, the symptoms were similar to those observed in the original diseased plants and the fungus on inoculated leaves was morphologically identical to that detected on their leaves, fulfilling Koch’s postulates. No disease developed on the controls. So far, E. euonymicola (formerly Oidium euonymi-japonici) has been found in only Euonymus spp. (Farr and Rossman 2016). In addition, Quercus spp. has been reported as the host of E. alphitoides. Recently, Sorbaria sorbifolia, Wisteria brachybotrys, and W. frutescens have been determined as additional hosts for E. alphitoides (Denton et al. 2016). This information indicates that E. alphitoides is able to infect a wide range of hosts and may pose a threat to multiple woody ornamental plant species. Further studies on the host and geographical ranges of E. alphitoides species are needed. To our knowledge, this is the first report of powdery mildew caused by E. alphitoides on E. japonica in Korea and in the world.References:Denton, G. J., et al. 2016. New Dis. Rep. 33:5. https://doi.org/10.5197/j.2044-0588.2016.033.005 Crossref, Google ScholarFarr, D. F., and Rossman, A. Y. 2016. Fungal Databases, Syst. Mycol. Microbiol. Lab. USDA-ARS, available at https://nt.ars-grin.gov/fungaldatabases/ Google ScholarLee, H. B. 2013. Plant Dis. 97:287. https://doi.org/10.1094/PDIS-08-12-0774-PDN Link, ISI, Google ScholarTakamatsu, S., et al. 2007. Mycol. Res. 111:809. https://doi.org/10.1016/j.mycres.2007.05.013 Crossref, Google ScholarThis work was supported by the Project on Survey and Discovery of Korean Indigenous Species funded by NIBR of the Ministry of Environment (MOE), Republic of Korea.DetailsFiguresLiterature CitedRelated Vol. 101, No. 2 February 2017SubscribeISSN:0191-2917e-ISSN:1943-7692 Metrics Article History Issue Date: 13 Jan 2017Published: 16 Nov 2016First Look: 17 Oct 2016Accepted: 10 Oct 2016 Pages: 385-385 Information© 2017 The American Phytopathological SocietyCited byAmpelomyces quisqualis (hyperparasite of Erysiphaceae)CABI Compendium, Vol. CABI CompendiumErysiphe alphitoides (powdery mildew of oak)CABI Compendium, Vol. CABI CompendiumFirst report of leaf blight disease of Euonymus japonicus caused by Botryosphaeria dothidea in ChinaCrop Protection, Vol. 141First Report of Powdery Mildew Caused by Erysiphe alphitoides on Ipomoea obscura in ChinaYingwen Pan, Hua Wu, and Rong Di25 March 2020 | Plant Disease, Vol. 104, No. 6First Report of Powdery Mildew Caused by Erysiphe alphitoides on Exochorda racemosa in ChinaY. 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