First report of Dactylonectria torresensis causing black root rot of strawberries in Kyrgyzstan
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First report of Dactylonectria torresensis causing black root rot of strawberries in Kyrgyzstan Ismail Erper 1,2
&
Goksel Ozer 3 & Mehtap Alkan 3 & Sezim Zholdoshbekova 1 & Muharrem Turkkan 4
Received: 17 May 2020 / Accepted: 17 November 2020 # Società Italiana di Patologia Vegetale (S.I.Pa.V.) 2020
Keywords Fragaria × ananassa . Dactylonectria . Black root rot
Kyrgyzstan produces 2331 tons of strawberries annually at 427 ha (FAOSTAT 2020). In June 2019, strawberry plants showed some aboveground symptoms including stunting, lack of vigor, smaller fruit size, and leaf chlorosis with the incidence of 5% in the fields in Bishkek, Kyrgyzstan (Latitude: 42°83′44“N, Longitude: 74°57’42”E). The root systems of plants were smaller than healthy ones, and their feeder and main roots were mostly destroyed and showed sunken and necrotic black lesions. Diseased sections 1–2 cm length from main roots were excised and superficially disinfected with 1% NaClO for 2 min and rinsed in sterile distilled water. The sections (2–3 mm long) were cultured on Potato Dextrose Agar (PDA) amended with 200 mg streptomycin sulphate and 50 mg chloramphenicol l−1 at 20 °C in darkness. Fungal isolates were purified by single-hypha technique to new PDA and incubated at 20 °C for a week under a 12 h light/12 h dark cycle. The colonies were cottony and beige to chestnut in color. Macroconidia were elongate, hyaline, straight or slightly curved, and mostly three-septate (31.4–41.3 × 5.9–8.1 μm) while microconidia were ellipsoid, hyaline, straight, and rarely one-septate (9.7–17.3 × 3.4– 4.8 μm). The fungus was identified as Dactylonectria spp. according to Cabral et al. (2012) and Lombard et al. (2014). The internal transcribed spacers (ITS) and the large subunit
(LSU) of ribosomal DNA, and histone H3 (HIS) gene sequences of three representative isolates were amplified and deposited in GenBank under accession Nos. MT071293–95, MT071296–98 and MT075866–68, respectively. These sequences showed 100% nucleotide identities with those of Dactylonectria torresensis type isolate Cyl138 (KP823916, KP823927 and KP823904, respectively). Pathogenicity was performed with colonized perlite medium like described Weber and Entrop (2017). Strawberry plants were inoculated with 25 ml perlite medium colonized with isolate “5O” when planted into pots which were filled with 2 l of a sterile mixture of peat, vermiculite, and soil (1;1;1, v/v). Untreated plants as control were inoculated only with sterile perlite medium. Pots were transferred to a growth room with a daily 16-h photoperiod at 20 °C. Black lesions were observed at the roots of infected plants after 8 weeks, while the controls remained asymptomatic. The pathogen was re-isolated with a frequency of 100%, fulfilling Koch’s postulates. To our knowledge, this is the first report of Dactylonectria torresensis causing black root rot of strawberries in Kyrgyzstan.
* Ismail Erper [email protected]; [email protected]
Research involving human participants and/or animals The authors declare
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