Pleosporales » Didymellaceae » Didymella

Didymella negriana

Didymella negriana (Thüm.) Qian Chen & L. Cai, in Chen, Jiang, Zhang, Cai & Crous, Stud. Mycol. 82: 178 (2015)

Index Fungorum number: IF 814112; Facesofungi number: FoF 03830

            Opportunistic pathogen on stems of Vitis vinifera. Sexual morph: Not observed. Asexual morph: Conidiomata on PDA 75–200 µm (x̄ =120 µm, n = 10) diam., pycnidial, solitary or confluent, scattered, globose or irregular, glabrous, initially citrine-honey to sienna-olivaceous, but later turn black. Pycnidial wall thin-layered, pigmented. Conidial exudate saffron to pale vinaceous. Conidiogenous cells 6–10 × 3–7 µm (x̄ = 8 × 5 µm, n = 20), hyaline, smooth-walled, globose to bottleshaped. Conidia 5–7 × 3–5 µm (x̄ = 6 × 3 µm, n = 30), ellipsoid to oblong, straight or slightly curved, initially hyaline, smooth-walled, acutely rounded at both ends, with several guttules.

            Culture characteristics: Colonies on PDA, regular, floccose to woolly, circular, smoke grey aerial mycelium on the surface, reverse olivaceous grey, slow growing, reach 5 cm diam. after 7 days at 20 °C.

Material examined: ITALY, Province of Forlì-Cesena, Teodorano - Meldola, on dead and aerial branch of Vitis vinifera (Vitaceae), 16 February 2016, Erio Camporesi (MFLU 15–1086), ex-type living culture, MFLUCC 16–1394.

Notes: According to phylogenetic analyses by Jayawardena et al.(2018) the combined LSU, ITS, RPB2 and β-tubulin sequence data of Didymella species, revealed their new isolates cluster together in a well-defined clade with Didymella negriana (CBS 358.71) with relatively high bootstrap and Bayesian probabilities (100% MP/1.00 PP). This species has been reported as a common opportunistic pathogen associated with disease symptoms on leaves, fruits, and stems of Vitis vinifera in southern Europe. The pathogen is often misidentified as Phoma viticola (currently known as Diaporthe ampelina), another pathogen of grapevine (de Gruyter et al. 1998).

 

Figure x.  Didymella negriana. a. Host tissue from which the species was isolated b. Saffron to pale vinaceous conidial mass on PDA c. Conidiogenesis d. Hyphae e. Conidia f–g. Upper view (f). and reverse view (g). of colony on PDA. Scale bars: a=1 mm, b=2 mm, c–e=10 μm.

 

References:

 

Jayawardena RS, Hyde KD, Chethana KW, Daranagama DA et al. 2018 Saprotrophic fungi on Vitis in China, Italy, Russia and Thailand. Mycosphere notes 9, 1–114.

de Gruyter J, Noordeloos ME, Boerema GH. 1998 – Contributions towards a monograph of Phoma (Coelomycetes) – I. 3. Section Phoma: taxa with conidia longer than 7 μm. Persoonia 16. 471–490.

 

Last Update: 11 September 2021

 

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