Acaulospora gedanensis Błaszk.

In PVLG

SPORES single in the soil; develop laterally, directly on the neck of a sporiferous saccule (sessile spores); pale yellow (3A3) to lemon yellow (3B8); globose to subglobose; (55-)65(-75) µm diam.

 

 

SUBCELLULAR STRUCTURE OF SPORES composed of a spore wall and two inner germination walls.

In PVLG
In PVLG
In PVLG+ Melzer's
Spore wall with two layers (swl1 and 2).

Layer 1 evanescent, hyaline, up to 0.5 µm thick, continuous with the wall of the sporiferous saccule.

Layer 2 laminate, smooth, pale yellow (3A3) to lemon yellow (3B8), (2.5-)3.6(-4.3) µm thick.

Germination wall 1 contains one rigid, fragile hyaline, 0.3-0.5 µm thick layer (gw1).

Germination wall 2 consists of two adherent flexible, smooth, hyaline layers, each ca. 0.5 µm thick (gw2l1 and 2).

None of both the spore wall and germination walls stains in Melzer’s reagent.

GERMINATION ORB. Not found.

SPORIFEROUS SACCULE hyaline; globose to subglobose; 60-70 µm diam; neck 50-60 µm long, tapering from 17-20 µm diam at the saccule to 6-15 µm diam at the point of spore attachment. Saccule usually collapses or falls off in mature spores.
In PVLG

CICATRIC. A scar, circular, 6-10 µm diam, to oval-shaped, 6-7.5 x 7-10 µm.

 

 

MYCORRHIZAE. Acaulospora gedanensis has been associated in the field with vesicular-arbuscular mycorrhizal roots of many plants (Błaszkowski 1988, 1993, 1994). All attempts to establish this fungus in both trap and one-species cultures failed.

DISTRIBUTION. Acaulospora gedanensis has been described from spores isolated from a rhizosphere soil of Festuca ovina L. growing in Chalupy (54º46'N, 18º31’E) located in the Hel Peninsula (Błaszkowski 1988). This fungus has also been associated with many other plant species colonizing the Hel Peninsula (54º47’N, 18º25’E-54º36’N, 18º49’E) and areas adjacent to the Puck Gulf (54º43’N, 18º24’E; Błaszkowski 1993, 1994).

There is no information of the presence of Ac. gedanensis in other regions of both Poland and the world.

NOTES. Acaulospora gedanensis distinguishes its (1) small, yellow-coloured spores, (2) the rigid and fragile, one-layered inner germinal wall 1, as well as (3) the smooth outer layer and the non-reactive inner layer of the germinal wall 2.

Of the described fungi of the Glomeromycota forming coloured acaulosporioid spores, the only species producing spores similar in colour and somewhat in size to those of A. gedanensis is A. morrowiae. However, even the largest spores of the former species attain only the lower size range of those of the latter fungus [(55.0-)65.0(-75.0) µm diam when globose in A. gedanensis vs. (60.0-)75.6-80.0(-120.0) µm diam in A. morrowiae; Błaszkowski 1988; Morton 2002; Schenck et al. 1984]. The most important differences between A. gedanensis, A. morrowiae, and almost all the other known members of the genus Acaulospora reside in the phenotypic and biochemical properties of the components of the two inner germinal walls. While the first inner germinal wall of spores of A. gedanensis consists of one rigid, easily cracking layer, that of spores of the other Acaulospora spp. is generally composed of two flexible to semi-flexible layers, never cracking in even vigorously crushed specimens (Błaszkowski 2003; Morton 2002). Moreover, the upper surface of the outer layer of the second germinal wall of spores of almost all species of the genus Acaulospora is ornamented with granular excrescences (a beaded layer) and this layer adheres to either a flexible or a plastic inner layer staining more or less intensively in Melzer's reagent. In contrast, the upper surface of the outer layer of the second germinal wall of spores of A. gedanensis is smooth and this layer is associated with a flexible inner layer, but not staining in Melzer's reagent.

The rigidity and fragility of the first inner germinal wall, as well as the smooth upper surface of the outer layer of the second germinal wall and the nonreactivity of its inner layer in Melzer's reagent suggest A. gedanensis to be more closely related to members of the genus Ambispora than to Acaulospora spp. Molecular investigations of spores of the two fungi are needed to confirm this supposition.

REFERENCES

Błaszkowski J. 1988. Four new species of the Endogonaceae (Zygomycotina) from Poland. Karstenia 27, 37-42.

Błaszkowski J. 1993. Comparative studies of the occurrence of arbuscular fungi and mycorrhizae (Glomales) in cultivated and uncultivated soils of Poland. Acta Mycol. 28, 93-140.

Błaszkowski J. 1994. Arbuscular fungi and mycorrhizae (Glomales) of the Hel Peninsula, Poland. Mycorrhiza 5, 71-88.

Błaszkowski J. 2003. Arbuscular mycorrhizal fungi (Glomeromycota), Endogone and Complexipes species deposited in the Department of Plant Pathology, University of Agriculture in Szczecin, Poland. http://www.agro.ar.szczecin.pl/~jblaszkowski/.

Morton J. B. 2002. International Culture Collection of Arbuscular and Vesicular-Arbuscular Mycorrhizal Fungi. West Virginia University. http://www.invam.caf.wvu.edu/.

Schenck N. C., Spain J. L., Howeler R. H. 1984. Several new and unreported vesicular-arbuscular mycorrhizal fungi (Endogonaceae) from Colombia. Mycologia 76, 685-699.