First report of leaf blight caused by Colletotrichum fuscum on Coreopsis lanceolata in Italy
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First report of leaf blight caused by Colletotrichum fuscum on Coreopsis lanceolata in Italy Angelo Garibaldi 1 & Domenico Bertetti 1 & Vladimiro Guarnaccia 1 & Slavica Matić 1 & Incoronata Luongo 2 & Maria Lodovica Gullino 1 Received: 13 November 2019 / Accepted: 27 February 2020 # Società Italiana di Patologia Vegetale (S.I.Pa.V.) 2020
Keywords Ornamentals . Lanceleaf coreopsis . Leaf blight
During June 2018, about 25 plants of Coreopsis lanceolata growing in a private garden located in Biella province (north of Italy) showed a leaf blight, causing black, irregular necrosis with a well-defined border, that expanded up to the most part of the leaf. A fungus was isolated from the margin of affected tissue and was grown on sterilised leaves of the host distributed on PDA, for 10 days. On this medium, colonies produced septate, brown setae with round to more or less acute ends, 84.1–162.0 μm in length and 3.0–5.2 μm at the base. On the same medium, the fungus produced light grey, cylindrical in shape with rounded ends, conidia that measured 10.9–20.1 × 2.5–5.0 (average 15.3 × 3.7) μm (n = 50). A single isolate was grown on PDA to extract the DNA, using the E.Z.N.A. Fungal DNA Mini Kit (Omega Bio-Tek, Darmstadt, Germany). Successively, for a PCR reaction were used primers for ITS (internal transcribed spacer region), gapdh (glyceraldehyde-3phosphate dehydrogenase), act (actin) and tub2 (beta-tubulin) loci, as reported in Guarnaccia et al. (2019). Four sequences with 546 (ITS), 173 (gapdh), 261 (act) and 507 (tub2) bp. (GenBank accession Nos. MN602562, MT013215,
* Domenico Bertetti [email protected] 1
Centre of Competence for the Innovation in the Agro-Environmental Sector (AGROINNOVA), University of Turin, Largo Paolo Braccini 2, 10095 Grugliasco (TO), Italy
2
DiSAFA, University of Turin, Largo Paolo Braccini 2, 10095 Grugliasco (TO), TO, Italy
MN615838, and MN615837, respectively) were obtained. A BLASTn analysis (Altschul et al. 1997) of these sequences identified the fungus as Colletotrichum fuscum with 99.84% of similarity for ITS and 100% for the other sequences of the ex-type strain CBS 133701 (ITS KM105174, gapdh KM105524, act KM105384, tub2 KM105454). A phylogenetic tree generated on the concatenated 4-locus sequences alignment, has been generated and showed the strain collected in this study, clustering with the ex-type strain of Col. fuscum (Fig. 1). Pathogenicity test was performed on three healthy plants of C. lanceolata artificially inoculated with a suspension of conidia and mycelium of the pathogen, sprayed on leaves, at the concentration of 1 × 105 CFU/ml. Controls were sprayed with sterile water. All plants were kept in a humid chamber for 7 days, at 18 to 25 °C. Symptoms of the disease appeared only on inoculated plants, whereas controls remained symptomless. To our knowledge, this is the first report of Col. fuscum on Cor. lanceolata in Italy, as well as worldwide.
J Plant Pathol Fig. 1 Multilocus ITS, gapdh, act and tub2 phylogenetic tree by maximum likelihood (ML) m
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