Scutellospora pellucida

(Nicol. & N.C. Schenck) C. Walker & F.E. Sanders

SPORES single in the soil; formed terminally on a bulbous subtending hypha; hyaline to yolk yellow (4B8); globose to subglobose; (130-)195(-235) µm diam; sometimes ovoid; 130-155 x 160-235 µm.

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

In PVLG
In PVLG+Melzer's reagent
In PVLG+Melzer's reagent

Spore wall composed of two layers (swl1-3).

Layer 1 permanent, smooth, hyaline, (1.0-)1.5(-2.5) µm thick, better visible in spores crushed in Melzer’s reagent, in which it is nonreactive in contrast to layer 2 staining darkly in this reagent; this layer frequently slightly separates from layer 2 in spores mounted in lactic acid-based mountants.

Layer 2 laminate, hyaline to yolk yellow (4B8), (3.0-)7.1(-9.2) µm thick, staining dark purple (14F8) in Melzer’s reagent.

Germination wall 1 contains two layers (gw1l1 and 2).

Layer 1 flexible, hyaline, <0.5 µm thick.

Layer 2 flexible, hyaline, (0.8-)1.2(-1.9) µm thick.

Germination wall 2 composed of two layers (gw2l1 and 2).

In PVLG+Melzer's

 

Layer 1 flexible, coriaceous, hyaline, (1.5-)2.8(-5.3) µm thick, usually reddish white (8A2) to pale red (8A3) in Melzer’s reagent.

Layer 2 plastic, hyaline, 5-25 µm thick in PVLG, 1.0-3.0 µm thick and beetroot purple (13D8) in Melzer’s reagent.

 

SPOROGENOUS CELL formed terminally on a sparsely septate sporophore; ovoid to clavate; (30.0-)35.0(-43.5) µm wide; hyaline to yolk yellow (4B8).

Structure of sporogenous cell composed of two layers, continuous with spore wall layers 1 and 2.

PVLG

Layer 1 hyaline, <0.3-0.5 µm thick, very difficult to see.

Layer 2 hyaline to yolk yellow (4B8), 1.8-3.0 µm thick at the spore base.

 

GERMINATION SHIELD ellipsoid; hyaline to pale yellow (4A3); 65-80 x 100-120 µm; with deep folds partitioning 4-7 lobes with smooth margins; formed on germination wall 2.
In PVLG

AUXILIARY CELLS rarely single in the soil, usually in loose clusters of 2-10; hyaline to pale yellow (4A3); pyriform to irregular; 30.0-42.0 µm; produced on coiled hyphae, 2.2-5.8 µm diam, concolorous with auxiliary cells.

 

 

MYCORRHIZAE. Spores of S. pellucida have been found associated in the field with many cultivated and uncultivated plant species (Blaszkowski 1989, 1993a, b, 1994; Blaszkowski et al. 2002; Tadych and Blaszkowski 2000). Attempts to establish one-species cultures of this fungus failed.

DISTRIBUTION. In Poland, S. pellucida has been widely distributed in both cultivated and uncultivated soils (Blaszkowski 1989, 1993a, b; Iwaniuk and Blaszkowski 2004). However, this fungus has generally occurred infrequently. Most of the S. pellucida specimens collected in Poland came from dune soils, including those of the Hel Peninsula (54o47’N, 18o25’E-54o36’N, 18o49’E; Blaszkowski 1994), the Gdansk and Szczecin coasts (Blaszkowski 1993b), Slowinski National Park (54o45’N, 17o26’E; Tadych and Blaszkowski 2000), and the Bledowska Desert (50o22’N, 19o34’E; Blaszkowski et al. 2002).

Scutellospora pellucida occurs in the whole world. This fungus has originally been described from spores isolated from a soybean-rhizosphere soil collected in Florida (Nicholson and Schenck 1979). Later, spores of S. pellucida have been found, e. g., in other states of the USA (Hetrick and Bloom 1983; Koske 1987; Miller et al. 1985; Rose 1988), Italy (Giovannetti 1985), Israel and Turkey (Blaszkowski et al. 2001; Blaszkowski, pers. observ.).


NOTES. When observed under a dissecting microscope, mature spores of S. pellucida most resemble those of S. fulgida due to their similar size and colour (Koske and Walker 1986; Morton 1995). Older and field-collected spores of S. pellucida are also reminiscent of light-coloured spores of S. calospora (Koske and Walker 1986; Morton 2000; Nicolson and Gerdemann 1968; Nicolson and Schenck 1979).

These fungi differ in the subcellular structure of spores and the biochemical properties of its components. The subcellular structure of spores of S. pellucida and S. calospora is identical, whereas spores of S. fulgida lack either the third spore wall layer and the germination wall 2 of the two former species (Morton 1995, 2000). Additionally, the laminate spore wall layer of only S. pellucida spores stains red in Melzer’s reagent.

REFERENCES

Blaszkowski J. 1989. Polish Endogonaceae. I. Acaulospora bireticulata, Entrophospora infrequens, Glomus caledonium, and Scutellispora pellucida. Karstenia 29, 1-10.

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

Blaszkowski J. 1993b. The occurrence of arbuscular fungi and mycorrhizae (Glomales) in plant communities of maritime dunes and shores of Poland. Bull. Pol. Ac. Sci. Biol. Sci. 41, 377-392.

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

Blaszkowski J., Tadych M., Madej T. 2002. Arbuscular mycorrhizal fungi (Glomales, Zygomycota) of the Bledowska Desert, Poland. Acta Soc. Bot. Pol. 71, 71-85.

Blaszkowski 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.

Giovannetti M. 1985. Seasonal variations of vesicular-arbuscular mycorrhizas and Endogonaceous spores in a maritime sand dunes. Trans. Br. Mycol. Soc. 84, 679-684.

Hetrick B. A. D., Bloom J. 1983. Vesicular-arbuscular mycorrhizal fungi associated with native tall grass prairie and cultivated winter wheat. Can. J. Bot. 61, 2140-2146.

Iwaniuk A., Blaszkowski J. 2004. Arbuscular fungi and mycorrhizae of agricultural soils of the Western Pomerania . Part II. Distribution of arbuscular fungi. Acta Mycol. 39(2), 3-18.

Koske R. E. 1987. Distribution of VA mycorrhizal fungi along a latitudinal temperature gradient. Mycologia 79, 55-68.

Koske R. E., Walker C. 1986. Species of Scutellospora (Endogonaceae) with smooth-walled spores from maritime sand dunes: two new species and a redescription of the spores of Scutellospora pellucida and Scutellospora calospora. Mycotaxon 27, 219-235.

Miller D. D., Domoto P. A., Walker C. 1985. Mycorrhizal fungi at eighteen apple rootstock plantings in the United States. New Phytol. 100, 379-391.

Morton J. M. 1995. Taxonomic and phylogenetic divergence among five Scutellospora species based on comparative developmental sequences. Mycologia 87, 127-137.

Morton J. B. 2000. International Culture Collection of Arbuscular and Vesicular-Arbuscular Mycorrhizal Fungi. West Virginia University.

Nicolson T. H., Gerdemann J. W. 1968. Mycorrhizal Endogone species. Mycologia 60, 313-325.

Nicolson T. H., Schenck N. C. 1979. Endogonaceous mycorrhizal endophytes in Florida. Mycologia 71, 178-198.

Rose S. 1988. Above and belowground community development in a maritime sand dune ecosystem. Plant and Soil 109, 215-226.

Tadych M., Blaszkowski J. 2000. Arbuscular fungi and mycorrhizae (Glomales) of the Slowinski National Park, Poland. Mycotaxon 74, 463-483.