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SPORES single in the soil; greyish orange (5B3) to brownish orange (6C8); globose to subglobose; (80-)160(-230) µm diam; sometimes irregular; 80-150 x 95-230 µm; with one subtending hypha.
SUBCELLULAR STRUCTURE OF SPORES consists of one wall with two layers (swl1 and 2).
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In PVLG |
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Layer 1 evanescent, hyaline, (1.5-)2.1(-3.8) µm thick, staining reddish white (11A2) in Melzer’s reagent, usually completely sloughed in mature spores.
Layer 2 laminate, greyish orange (5B3) to brownish orange (6C8), (2.9-)5.5(-6.8) µm thick.
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In PVLG
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Wall of subtending hypha greyish orange (5B3) to brownish orange (6C8); 2.8-6.5 µm thick; composed of two layers (shwl1 and 2), continuous with spore wall layers 1 and 2; layer 1 rarely present in mature spores.
Pore closed by a curved septum, continuous with the innermost sublayers of the laminate spore wall layer 2.
GERMINATION. A germ tube emerges from the lumen of the subtending hypha.
MYCORRHIZAE. In roots of Zea mays L., mycorrhizae of Gl. coronatum consisted of arbuscules, vesicles, as well as intra- and abundant extraradical hyphae staining intensively in 0.1% trypan blue. Arbuscules were numerous and evenly distributed along the roots examined.
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In roots of Z. mays |
From roots of Z. mays |
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DISTRIBUTION. Glomus coronatum has originally been described from spores isolated from under Anacyclus radiatus Loisel. growing in a maritime sand dune system located near Follonica, Tuscania, Italy (Giovannetti et al.1991). According to Dodd et al. (1996), spores of this fungus were earlier found in Israel (Dodd and Krikun 1984), Italy (Giovannetti and Nicolson 1983), Libya (El-Gahmi et al. 1976), Portugal, Spain, and Australia (Sward et al. 1978). The author of this website has regularly isolated abundant populations of Gl. coronatum spores from dunes of the Mediterranean Sea located in Israel (Błaszkowski et al. 2001), Turkey, France, Spain, Portugal, and Morocco, Africa (Błaszkowski, pers. observ.).
Błaszkowski (1994) reported the occurrence of Gl. coronatum in Poland and Germany. The spores of that fungus were similar in colour, size, and had an outer layer of their wall expanding in lactic acid-based mountants, as those described by Giovannetti et al. (1991). However, they markedly differed in the shape of the subtending hypha (cylindrical to flared vs. funnel-shaped in Gl. coronatum). Reexamination and comparable studies of the two fungi showed that the Polish and German collections represent an undescribed species.
Recently, Gl. coronatum has been encountered in cultivated soils of the plain of the upper Rhine River valley located in France, Germany, and Switzerland (Oehl et al. 003). However, as the authors of the paper stated, the identification of the spores found is not valid.
NOTES. The distinctive characters of Gl. coronatum are its large and greyish orange to brownish orange spores and the wide, funnel-shaped subtending hypha. The fungus most resembling Gl. coronatum is Gl. mosseae (Nicol. & Gerd.) Gerd. & Trappe. The two fungi produce spores similar in size with a funnel-shaped subtending hypha. However, the spores of Gl. mosseae are markedly lighter and differ in the structure of their wall. The wall of Gl. coronatum spores consists of two layers, whereas that of spores of Gl. mosseae is 3-layered.
Additionally, Gl. mosseae is one of the most widely distributed arbuscular fungus in the world, and both literature data and observations of the author of this website suggest that Gl. coronatum is restricted to warm regions.
According to Giovannetti et al. (1991), Gl. coronatum produces spores in sporocarps surrounded by a peridium. Additionally, the outer spore wall layer of this fungus was characterized as a structure expanding in lactic acid-based mountants, as the outer spore wall layer of Gl. pansihalos S.M. Berch & Koske. All the spores isolated by the author of this website from field-collected soil samples, as well as from trap and one-species cultures occurred singly and their outer layer did not expand either in lactic acid or PVLG.
REFERENCES
Błaszkowski J. 1994. First record and notes on Glomus coronatum in Poland and Germany. Mycologia 86, 630-634.
Błaszkowski J., Tadych M., Madej T., Adamska I., Iwaniuk A. 2001. Arbuscular mycorrhizal fungi (Glomales, Zygomycota) of Israeli soils. Mat. II Polsko-Izraelskiej Konf. Nauk. nt. „Gospodarowanie zasobami wodnymi i nawadnianie roslin uprawnych”. Przeglad naukowy Wydz. Inz. Ksztalt. Srod. 22, 8-27.
Dodd J. C., Krikun J. 1984. Observations on endogonaceous spores in the Negev desert (Israel). Trans. Br. Mycol. Soc. 82, 536-540.
Dodd J. C., Rosendahl S., Giovannetti M., Broome A., Lanfranco L., Walker C. 1996. Inter- and intraspecific variation within the morphologically-similar arbuscular mycorrhizal fungi Glomus mosseae and Glomus coronatum. New Phytol. 133, 113-122.
El-Giahmi A. A., Nicolson T. H., Daft M. J. 1976. Endomycorrhiza fungi from Libyan soils. Trans. Br. Mycol. Soc. 67, 164-169.
Giovannetti M., Nicolson T. H. 1983. Vesicular-arbuscular my- corrhizas in Italian sand dunes. Trans. Br. Mycol. Soc. 80, 552-557.
Giovannetti M., Avio L., Salutini L. 1991. Morphological, cytochemical, and ontogenetic characteristics of a new species of vesicular-arbuscular mycorrhizal fungus. Canad. J. Bot. 69, 161-167.
Oehl F., Sieverding E., Ineichen K., Mader P., Boller T., Wiemken A. 2003. Impact of land use intensity on the species diversity of arbuscular mycorrhizal fungi in agroecosystems of Central Europe. Appl. Environ. Microbiol.69, 2816-2824.
Sward R. J., Hallam N. D., Holland A. A. 1978. Endogone spores in a heathland area of South-Eastern Australia. Aust. J. Bot. 26, 29-43.