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First Report of Necrotic Leaf Spot Caused by Plectosphaerella cucumerina on Aquilegia flabellata in Italy

2021; American Phytopathological Society; Volume: 105; Issue: 8 Linguagem: Inglês

10.1094/pdis-11-20-2425-pdn

1943-7692

A. Garibaldi, D. Bertetti, Giulia Tabone, I. Luongo, M. L. Gullino,

Powdery Mildew Fungal Diseases

HomePlant DiseaseVol. 105, No. 8First Report of Necrotic Leaf Spot Caused by Plectosphaerella cucumerina on Aquilegia flabellata in Italy PreviousNext DISEASE NOTE OPENOpen Access licenseFirst Report of Necrotic Leaf Spot Caused by Plectosphaerella cucumerina on Aquilegia flabellata in ItalyA. Garibaldi, D. Bertetti, G. Tabone, I. Luongo, and M. L. GullinoA. GaribaldiCentre of Competence AGROINNOVA, University of Torino, 10095 Grugliasco, ItalySearch for more papers by this author, D. BertettiCentre of Competence AGROINNOVA, University of Torino, 10095 Grugliasco, ItalySearch for more papers by this author, G. TaboneCentre of Competence AGROINNOVA, University of Torino, 10095 Grugliasco, ItalySearch for more papers by this author, I. LuongoDISAFA, University of Torino, 10095 Grugliasco, ItalySearch for more papers by this author, and M. L. Gullino†Corresponding author: M. L. Gullino; E-mail Address: marialodovica.gullino@unito.ithttps://orcid.org/0000-0002-7706-1915Centre of Competence AGROINNOVA, University of Torino, 10095 Grugliasco, ItalyDISAFA, University of Torino, 10095 Grugliasco, ItalySearch for more papers by this author AffiliationsAuthors and Affiliations A. Garibaldi1 D. Bertetti1 G. Tabone1 I. Luongo2 M. L. Gullino1 2 † 1Centre of Competence AGROINNOVA, University of Torino, 10095 Grugliasco, Italy 2DISAFA, University of Torino, 10095 Grugliasco, Italy Published Online:18 Aug 2021https://doi.org/10.1094/PDIS-11-20-2425-PDNAboutSectionsView articlePDFPDF Plus ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat View articleFan columbine (Aquilegia flabellata Siebold & Zucc.), Ranunculaceae family, is a perennial herbaceous plant producing blue-purple flowers that is used in gardens and for cut flower production. During June 2020, brown spots (0.5 to 1.0 mm in diameter) appeared on 20% of leaves of 115 plants of A. flabellata growing in a private garden located in Biella province (northern Italy). Progressively, spots enlarged to 5 to 6 mm and formed irregular necrosis surrounded by chlorotic halos that sometimes coalesced. Several affected leaves were disinfected in sodium hypochlorite (1%) for 30 s and then rinsed in sterile water. Fragments were excised from the margins of necrosis and plated on potato dextrose agar (PDA) amended with streptomycin sulfate (25 mg/liter). Plates were maintained in a 17-h photoperiod at 25 ± 1°C for 9 days before subculturing onto PDA medium. The fungal morphology was pale orange with hyaline mycelium that formed hyphal coils. Conidia were ellipsoidal with rounded apices, not septate, guttulate, and measured 4.2 to 8.8 × 1.8 to 3.2 (average 6.5 × 2.4) µm (length/width ratio 2.7; n = 50). Conidia were supported by straight, sometimes sinuous, tapered phialides. Phialides were 5.1 to 22.6 (average 11.2) µm (n = 30) and sometimes with a septum near the base. These morphological characteristics resembled those of the fungi Plectosphaerella (Carlucci et al. 2012). The DNA was extracted with an E.Z.N.A. Plant DNA Kit (Omega Bio-Tek) from pure cultures of three isolates belonging to the collection of Agroinnova. PCR was carried out with primers ITS1/ITS4 (White et al. 1990), and the PCR products were purified and sequenced, obtaining 481-bp-long sequences (GenBank accession nos. MW205832, MW205833, MW205834). BLASTn analysis (Altschul et al. 1997) of these sequences showed 99.6% nucleotide identity with the sequence of Plectosphaerella cucumerina (Lindf.) W.Gams (ex-type CBS 131.739; GenBank accession no. LR026809). Pathogenicity testing was performed inoculating the isolates 20/14-1, 20/14-2, and 20/14-3 on 5-month-old healthy plants of A. flabellata (nine plants per each isolate). Inoculum was prepared from colonies grown on PDA at 21 ± 1°C for 18 days. A conidial suspension was obtained for each isolate to the final concentration of 5 × 105 conidia/ml and sprayed on leaves (5 ml per plant). Nine control plants were sprayed with sterile water. Plants were maintained in moistened plastic bags for 7 days, at temperatures ranging from 15 to 25°C. About 15 days after inoculation, the first spots appeared on inoculated leaves, which later expanded and became necrotic, whereas control plants remained healthy. P. cucumerina has been reported in several countries, on many hosts (Farr and Rossman 2020); however, this is the first report of this pathogen on A. flabellata. The incidence of P. cucumerina on fan columbine constitutes a problem in Italy due to the widespread use of A. flabellata in public gardens and the difficulty of managing this disease.The author(s) declare no conflict of interest.References:Altschul, S. F., et al. 1997. Nucleic Acids Res. 25:3389. https://doi.org/10.1093/nar/25.17.3389 Crossref, ISI, Google ScholarCarlucci, A., et al. 2012. Persoonia 28:34. https://doi.org/10.3767/003158512X638251 Crossref, ISI, Google ScholarFarr, D. F., and Rossman, A. Y. 2020. Fungal Databases, Syst. Mycol. Microbiol. Lab., ARS, USDA. Retrieved November 13, 2020, from https://nt.ars-grin.gov/fungaldatabases/. Google ScholarWhite, T. J., et al. 1990. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA. Google ScholarThe author(s) declare no conflict of interest.DetailsFiguresLiterature CitedRelated Vol. 105, No. 8 August 2021SubscribeISSN:0191-2917e-ISSN:1943-7692 DownloadCaptionComparison of banana plants in silicon-deficient soil amended or nonamended with calcium silicate and infected by Fusarium oxysporum f. sp. cubense (W. Zellner et al.). Photo credit: A. A. Fortunato and F. A. Rodrigues. Infected spicebush tree outer bark showing black vascular discoloration of the sapwood typical of laurel wilt (R. Olatinwo et al.). Photo credit: R. Olatinwo. Maize plants naturally infected by Bipolaris zeicola (S. S. Liu et al.). Photo credit: S. S. Liu. Metrics Downloaded 183 times Article History Issue Date: 1 Dec 2021Published: 18 Aug 2021Accepted: 2 Mar 2021 Page: 2247 Information© 2021 The American Phytopathological SocietyKeywordsfungiornamentalsepidemiologyThe author(s) declare no conflict of interest.