Ascochyta sojina sp. nov., a new pathogen on Glycine max (L.) Merr.
Ascochyta sojina sp. nov., ein neues Pathogen an Glycine max (L.) Merr.
Journal für Kulturpflanzen, 66 (9). S. 319–321, 2014, ISSN 1867-0911, DOI: 10.5073/JfK.2014.09.05, Verlag Eugen Ulmer KG, Stuttgart
Ascochyta sojina sp. nov., a new species collected on Glycine max (L.) Merr., differs from other species of Ascochyta on this host in the diameter of the pycnidia and in length and width of the conidia.
Key words: Ascochyta sojina sp. nov., Glycine max, symptoms, systematics, new species
Ascochyta sojina sp. nov., eine neue Art an Glycine max (L.) Merr., unterscheidet sich von anderen Arten der Gattung Ascochyta auf diesem Wirt im Durchmesser der Pyknidien und in Länge und Breite der Konidien.
Stichwörter: Ascochyta sojina sp. nov., Glycine max, Symptome, Systematik, neue Art
On soybean (Glycine spp.) we know four different species of Ascochyta, as there are A. sojae Miura, A. sojicola Abramov, A. pisi Lib. and A. phaseolorum Sacc. On leaves of Glycine max originating from a field at Bad Wimsbach in Upper Austria an Ascochyta species was identified which differs in the diameter of the pycnidia, length and width of conidia to the well-known species on Glycine spp.
For the determination of the fungus the usual mycological routine methods of light microscopy were adopted. Pycinidia and conidia of the fungus were stained with Wittmann’s Blue (Wittmann, 1970). Both have been measured using the programme labSense by Olympus.
The conidia of the new species differ in length and width from the above mentioned four species. In some cases the diameters of the pycnidia of A. sojina also deviate from other Ascochyta species on soybean (Tab. 1). In addition to the four so far known species Nelen described Ascochyta sojicola on soybean (Nelen, 1977), referring to a publication by Abramov (Abramov, 1938) where Ascochyta sojicola is only mentioned without a description by the author. This neglects the original description by Abramov (Abramov, 1931), also transliterated as Abramoff or Abramow. Nelen’s fungus is therefore regarded as homonym and a nomen superfluum.
Table 1. On Glycine spp. up to now described species of Ascochyta (in chronological order) according to the original descriptions
Species | Host | Synonyms and remarks | Diameter of pycnidia in μm | Length of conidia in μm | Width of conidia in μm | Characteristics of the conidia |
Ascochyta pisi | Phaseolus, Pisum, Cicer | In the literature Glycine spp. mentioned as host too. | up to 200 (250)1) | 14–16 | 4–6 | Oblong with 1 septum, in the midth constricted, hyaline |
Ascochyta phaseolorum | Phaseolus vulgaris | In the literature Glycine spp. mentioned as host too. | 100 | 10 | 3 | |
Ascochyta sojae Miura (1928) | Glycine soja (= G. max) | 90–120 | 12–18 | 4–4.5 | ||
Ascochyta sojicola (as sojaecola) Abramov (1931) | Glycine hispida | Current name: Phoma sojicola (Abramov) Kövics et al. (1999) | 90–220 | 8–11 | 3–5 | |
Ascochta sojicola Nelen (1977) | Glycine hispida | Illegitim, homonym of Ascochyta sojicola Abramov (1931) and nomen superfluum | 80–160 | 6.5–14 | 3.5 | |
1) according to the description in Mel’nik (2000) | ||||||
Kövics et al. (1999) transferred A. sojicola Abramov to the genus Phoma, because the observed conidia were mostly aseptate.
An additional species of Ascochyta on soybean, Ascochyta glycines Miura, only occurred in a list in Japan, not including the protologue (Guo, 2014). Ascochyta glycines was also reported (in Chinese) in: Flora of Gansu Economic Diseases, 282, 2002 (Guo, 2014). Symptoms are described as “Leaf spots circular, ellipsoid, at first brown, latter centre grayish white, margin brown, zonate and forming perforation, fusiform on stem and circular or irregular on seeds. Pycnidia globose or subglobose, brown, 102.8–134.2 μm diam. Conidia cylindrical, hyaline, rounded on ends, 1-septate, 4.2–10 × 2.3–4.2 μm”.
Bai (2003) considered that Ascochyta glycines was a synonym of Ascochyta sojae (pycinida 95–150 μm, conidia 6–13 × 2–3.5 μm) and Ascochyta glycines was a nom. inval. The dimensions of pycnidia and conidia differ among each other and from Ascochyta sojae Miura (Miura, 1928).
The dimensions of pycnidia and conidia of Ascochyta glycines Miura are comparable with the Ascochyta species found in Austria and not with Ascochyta sojae Miura.
The diameter of the pycnidia of the new species varies from 47.45–180.77 μm with an average of 109.29 μm. The ostioles measure 6.52–23.18 μm (average 14.75 μm). The conidia are 4.78–11.33 μm long (average 8.39 μm) and 1.53–3.76 μm wide (average 2.38 μm) and show one septum in the midth of the conidia.
Ascochyta sojina Bedlan sp. nov.
Index Fungorum IF550726
On leaves dark brown roundish or irregular shaped spots (Fig. 1). On stalks the spots are oblong-oval, dark brown surrounded, somewhat immerged (Fig. 2). Conidiomata (pycnidia) on the upper side of the leaf spots (Fig. 3). Pycnidia semi-immersed, dark brown, globose, 47.45–180.77 μm diameter (average 109.29 μm) (s. Fig. 4). The ostioles measure 6.52–23.18 μm (average 14.75 μm). The conidia are hyaline, oblong-cylindrical, rounded at the ends, 4.78–11.33 μm long with an average of 8.39 μm and 1.53–3.76 μm wide with an average of 2.38 μm and 1 septum in the midth (young conidia aseptate) (s. Fig. 5). At the septum sometimes constricted, at few conidia one cell is a little bit longer and some are slightly flexuose.
Fig. 1. Symptoms on upper side of leaf.
Fig. 2. Symptoms on stalk.
Fig. 3. Pycnidia on a leaf spot.
Fig. 4. Pycnidia (stained with Wittmann’s Blue).
Fig. 5. Conidia (stained with Wittmann’s Blue).
On living leaves and stalks of Glycine max (L.) Merr.
Type: Austria, Bad Wimsbach (Upper Austria). On living leaves of Glycine max (L.) Merr., 12 September 2013, leg. K. Mechtler, det. G. Bedlan (holotype, hb W).
The type specimen has been deposited at the Department of Botany, Natural History Museum, Vienna (hb W).
Thanks are due to Alain Lepretre, Julius Kühn-Institut (JKI), Federal Research Centre for Cultivated Plants in Berlin for providing original literature.
Abramov, I.N., 1931: Bolezni i Vrediteli Soievykh Bobov na Dal’nem Vostoke (Diseases and pests of Soybeans in the Far East), pamphlet issued by], Vladivostok: Dal’stazva (Far Eastern Plant Protection Station), 1-84 (p. 68).
Abramov, I.N., 1938: Bolezni sel’skokhozyaistvennykh rastenij na Dal’nem Vostoke. Khabarovsk. 1-286.
Bai, J.-K., 2003: Flora Fungorum Sinicorum Vol. 17, 75.
Guo, Y.-I., 2014: (private information).
Kövics, G.J., J. de Gruyter, H.A. van der Aa, 1999: Phoma sojicola comb. nov. and other hyaline-spored coelomycetes pathogenic on soybean. Mycol. Res. 103 (8), 1065-1070.
Mel’nik, V.A., 2000: Key to the fungi of the genus Ascochyta Lib. (Coelomycetes). Mitt. Biol. Bundesanst. Land-Forstwirtsch., Berlin-Dahlem, Heft 379, 192 S.
Miura, M., 1928: Flora of Manchuria and East Mongolia, III Cryptogams, Fungi (Industr. Contr. S. Manch. Rly, 27), 443.
Nelen, E.S., 1977: Species fungorum pycnidialium novae e parte australi orientis extremi. Nov. Sist. niz. Rast. 14, 105.
Wittmann, W., 1970: Ein neues Rezept zur Herstellung mykologischer Präparate. PflSchber., Bd. 41, Heft 5/6/7, 91-94.
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