Pleosporales » Didymellaceae » Ascochyta

Ascochyta medicaginicola

Ascochyta medicaginicola Qian Chen & L. Cai, Stud. Mycol. 82: 187 (2015)

Index Fungorum number: IF814129; Facesofungi number: FoF 2773 

Replaced synonym: Phoma medicaginis Malbr. & Roum., in Roumeguère, Fungi Selecti Galliaei Exs., Cent. 37: no. 3675 (1886)

Type: USA, Minnesota, from Medicago sativa, September 1953, M.F. Kernkamp, CBS H-16487, ex-type culture CBS 112.53.                                           

Saprobic on dead branch of Scabiosa sp. Sexual morph: Ascomata 143–162 µm high × 144–233 µm diam. (x̄ = 152 × 196 µm, n = 5), semi-immersed to erumpent, visible as raised, dark spots on the host surface, subglobose, solitary or small groups, scattered on the host surface, without papilla, with short ostiole in the centre, thin-walled, carbonaceous, dark brown or usually black. Peridium 17–28 µm wide, thin-walled, inner cells hyaline to pale brown, outer layer cells brown to dark brown, composed of flattened cells of textura angularis. Hamathecium 2.5–3.8 µm wide, comprising numerous, septate, cylindrical, cellular, pseudoparaphyses. Asci 46–67 × 12–15 µm (x̄ = 55 × 14 µm, n = 15), 8-spored, bitunicate, fissitunicate, cylindrical to cylindric-clavate, short pedicellate, rounded at the apex with acute ends, lacking an ocular chamber. Ascospores 17–22 × 7–9 µm (x̄ = 19 × 8 µm, n = 15), overlapping 1–2-seriate in the ascus, fusiform, 2-celled, narrowly fusoid with rounded ends, the cells above central septum often broader than the lower ones, constricted at the septum, deeply constricted at the septum, enlarged at the first cell, with small guttules in each cell, hyaline, lacking a mucilaginous sheath, smooth-walled. Asexual morph: Undetermined.

Culture characteristics: Colonies on PDA reaching 80 mm diam. after 7 days at 25 °C, circular colony, olivaceous to gray greenish, concentrically zonate, effuse mycelium, entire edge, reverse colony black in middle, grey olivaceous at the edge, without any diffusible pigments. Pycnidia globose to subglobose, without a distinct ostiole, glabrous, conidial matrix off whitish. Conidia sub-cylindrical, aseptate.

Material examined: ITALY, Province of Arezzo, near Moggiona, on dead branch of Scabiosa sp. (Caprifoliaceae), 1 June 2013, Erio Camporesi, IT1314 (MFLU 15-1481, new host record); Ibid. (HKAS 94550 bis).

GenBank Numbers: LSU: KY496720, ITS: KY496741, SSU: KY501111.

Note: We have collected the fungal isolate from dead aerial stem of Medicago sp. and it was identified as Ascochyta medicaginicola with the support from both morphology and phylogeny. Our isolate clustered with A. medicaginicola (CBS 404.65, BRIP450.51, CBS 112.53) and another strain of A. medicaginicola var. medicaginicola Q. Chen & L. Cai (CBS 316.90) in the combined LSU, ITS, RPB2 and TUB2 sequence phylogeny with 98% ML and 0.98 BYPP statistical support. This is the first report of Ascochyta medicaginicola on Scabiosa sp. (Caprifoliaceae) from Italy and the first report of a sexual morph for A. medicaginicola (Tibpromma et al. 2017).

 

Figure xx. Ascochyta medicaginicola (MFLU 15-1481). ab Appearance of ascomata on host substrate. c Section of ascoma. d Section of peridium. e Pseudoparaphyses. f–i Ascus. j–l Ascospores. Scale bars a = 100 µm, b = 200 µm, c = 100 µm, d = 20 µm, e = 2 µm, f–h = 10 µm, j–l = 5 µm.

References:

 

Hyde KD, Dong Y, Phookamsak R, Jeewon R et al. 2020 – Fungal diversity notes 1151–1276: taxonomic and phylogenetic contributions on genera and species of fungal taxa. Fungal Diversity 16, 1–273.

Tibpromma S, Hyde KD, Jeewon R, Maharachchikumbura SS et al. 2017 – Fungal diversity notes 491–602: taxonomic and phylogenetic contributions to fungal taxa. Fungal diversity 83, 1–261.

 

 

Last Update: 02 February 2021

 

 

 

Ascochyta medicaginicola Qian Chen & L. Cai, in Chen, Jiang, Zhang, Cai & Crous, Stud. Mycol. 82: 187 (2015)

Synonymy: Phoma medicaginis Malbr. & Roum., Fungi Selecti Galliaei Exs. 37: no. 3675 (1886)

Index Fungorum number: IF 814129; Facesofungi number: FoF ****

Saprobic on Scabiosa sp., forming numerous, conspicuous, rounded to oval, dark brown, conidomata. Sexual morph: Undetermined. Asexual morph: Coelomycetous. Conidiomata 100–150 μm high, 150–250 μm diam., pycnidial, solitary, separate, scattered or gregarious, globose, dark brown, immersed to semi-immersed, unilocular, thin-walled, with a single, papillate, centrally located ostiole. Peridium composed of 3–4 wall-layers, 15–30 μm wide, with outer 1–2-layers dark brown, inner 1–2-layers hyaline, with thin-walled cells of textura angularis. Conidiophores reduced to conidiogenous cells arising from the innermost wall-layer cells of the conidiomata. Conidiogenous cells 4–7 μm long × 5–8 μm wide, enteroblastic, phialidic, determinate, doliiform, and hyaline. Conidia 10–20 × 3.5–5.5 μm wide (x̄ = 15.5 × 5, n = 20), ellipsoidal to ovoid, hyaline, straight or slightly curved, 1-septate, constricted at the septum, obtuse at both ends, thin-walled, smooth-walled, guttulate

Culture characters: Colonies on PDA slow-growing, reaching 25 mm diam. after one month at 25–30 °C, circular, grey to black, white at the edge, flattened with dense, filamentous, aerial, fluffy hyphae; reverse black in the middle, white at the edge, without any diffusible pigments.

Material examined: ITALY, Province of Ravenna [RA], Zattaglia, on a dead twig of Scabiosa sp. (Caprifoliaceae), 30 December 2012, E. Camporesi IT-988 (MFLU 14-0812), living culture, MFLUCC 13-0485, ICMP 20794.

GenBank ITS: KP711359; LSU: KP711364; SSU: KP711369; ibid. (KUN! HKAS 83971).

Notes: Phoma medicaginis species is characterized by globose, large, pycnidia, with straight or slightly irregular, cylindrical conidia, often becoming 1-septate and variably guttulate (Sutton 1980). Our isolate (MFLUCC 13-0485) is morphologically similar with Ph. medicaginis, and the only distinguish morphological character is the dimension of conidia, but it should be noted that this character has proven not be very reliable in coelomycetes (Verkley et al. 2014). In the study of Chen et al. (2015) medicaginis taxa and medicaginis varieties were occupied as Ascochyta. As well as they introduced a new epithet to “medicaginis” as “medicaginicola” for the varieties of Phoma medicaginis. Currently, the taxa is synonymized as Ascochyta medicaginicola.

 

Figure x. Ascochyta medicaginicola (as Phoma medicaginis MFLU 14-0812 in Liu et al. (2015) a Specimen. b, c Black conidiomata on the host surface. d Vertical section of conidioma. e Ostiole. f, g Section of peridium. h–l. Conidiogenous cells and developing conidia. m, n Germinated spore. o, p Conidia. q, r Culture on PDA (note r; reverse). Scale bars: b=500μm, c=100μm, d=50μm, e–g=20μm, h–k=5μm, m–n=10μm, o–p=5μm, q–r=25 mm

 

References:

 

Chen Q, Jiang JR, Zhang GZ, Cai L et al. 2015 – Resolving the Phoma enigma. Studies in mycology. 82, 137-217.

Liu JK, Hyde KD, Jones EG, Ariyawansa HA et al. 2015 – Fungal diversity notes 1–110: taxonomic and phylogenetic contributions to fungal species. Fungal diversity 72, 1–97.

Sutton BC. 1980 – The Coelomycetes-Fungi imperfecti with pycnidia, acervuli and stromata. Commonwealth Mycological Institute, Kew, 496 pp.

Verkley GJM, Dukik K, Renfurm R, Göker M et al. 2014 – Novel genera and species of Coniothyrium-like fungi in Montagnulaceae (Ascomycota). Persoonia 32, 25–51.

 

Last update: 02 February 2021, 11 June 2021

 

 

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