(Koske & C. Walker) C. Walker & F.E. Sanders
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SPORES single in the soil or in roots; formed terminally or laterally on a bulbous sporogenous cell; sunflower yellow (4A7) to apricot yellow (5B6); globose to subglobose; (250-)320(-380) µm diam; sometimes ovoid; 250-290 x 270-380 µm.
SUBCELLULAR STRUCTURE OF SPORES consists of a spore wall and one inner germination wall.
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Spore wall composed of two layers (swl1-2).Layer 1 permanent, brownish yellow (5C8) to yellowish brown (5D8), (0.7-)1.2(-1.7) µm thick, ornamented with warts, 0.3-0.5 µm wide and 0.2-0.7 µm high; usually tightly adherent to layer 2.
Layer 2 laminate, sunflower yellow (4A7) to apricot yellow (5B6), (6.6-)7.7(-9.5) µm thick, staining madder red (9A7) to crayfish red (9B8) in Melzer's reagent.
Germination wall contains two layers (gw1l1 and 2).
Layer 2 flexible, hyaline, (0.7-)1.0(-1.5) µm thick.
Layers 1 and 2 do not react in Melzer's reagent.
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In PVLG |
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Structure of sporogenous cell composed of two layers, continuous with spore wall layers 1 and 2.Layer 1 hyaline to orange white (5A2), 0.5-0.8 µm thick, usually difficult to see.
Layer 2 pale yellow (4A3) to apricot yellow (5B6), (2.0-)3.6(-5.1) µm thick at the spore base.
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In PVLG |
GERMINATION SHIELD cardioid; hyaline to light yellow (4A4); 70-90 x 100.0-150 µm; ornamented with straight and Y-shaped ridges at the margin and with arched with branches ridges surrounding germ tube initials; positioned on the inner germination wall. One to seven, hyaline to yellowish white (4A2), 5.0-7.5 µm diam germ tubes emerge from the germination shield.
AUXILIARY CELLS borne in soil singly or in clusters of 2-7; hyaline to yellowish white (3A2); lobed to irregular; 5.0-7.5 x 8.0-22.5 µm; with knobby projections; produced on coiled hyphae; 1.8-2.5 µm diam; concolorous with auxiliary cells.
MYCORRHIZAE. In Poland, S. persica has been found associated in the field with vesicular-arbuscular mycorrhizal roots of Ammophila arenaria (L.) Link, Helichrysum arenarium (L.) Moench, Hieracium umbellatum L., and Petasites spurius (Retz.) Rchb. (Blaszkowski and Tadych 1997; Tadych and Blaszkowski 2000). In one-species cultures with Plantago lanceolata L. and Sorghum vulgare Pers. as the plant hosts, S. persica formed mycorrhizae with arbuscules, as well as intra- and extraradical hyphae staining intensively in 0.1% trypan blue.
DISTRIBUTION. In Poland, S. persica has occurred in dunes of Swinoujscie (53o55’N, 14o14’E) and the Slowinski National Park (54o45’N, 17o26’E; Blaszkowski and Tadych 1997; Tadych and Blaszkowski 2000).
Scutellospora persica has originally been described from spores isolated from among roots of Solidago sempervirens L. growing in a barrier dune in New Jersey, USA (Koske and Walker 1985). This fungus has also been found in dunes of Italy (Puppi and Riess 1987), Greece (Blaszkowski and Tadych 1997), and the eastern coast of the US (Bergen and Koske 1984; Friese and Koske 1991; Gemma and Koske 1989; Gemma et al. 1989; Koske 1987; Koske and Gemma 1997; Koske and Walker 1985).
NOTES. The distinctive properties of S. persica are its large and sunflower yellow to apricot yellow spores ornamented with small warts. The warts are present in all spores coming from pot cultures. However, the outermost layer of spores of this fungus collected from the field frequently is partly smooth. The warts of these specimens usually are poorly visible. Uneven distribution of warts or their lack on a part of the surface of field-collected spores probably results from the degradative effects of soil parasites, as Morton (1995) suggested.
The two-layered wall structure of S. persica spores is well visible in both specimens collected from the field and pot cultures. The outer layer forming the surface of spores propagated in pot cultures frequently detaches from the laminated layer 2 of spores stored in a drop of lactic acid for a few days and, thereby, it is easy to recognize and characterize. Slight swelling of the outer spore wall layer in lactic acid also occurs in S. armeniaca Blaszk. (Blaszkowski, pers. observ.).
Two thin, hyaline layers constituting the inner germination wall of S. persica spores usually are tightly adherent to each other and rarely separate in even vigorously crushed spores. Hence, they frequently are visible as a 1-layered structure, especially in spores coming from the field. Disclosure of the two layers in the inner wall is relatively easy when spores slightly crushed with a needle are first stored in a drop of lactic acid for 12-24 h and then mounted in PVLG and crushed again.
The germination shields of S. persica spores found by one of the authors of this website, J. Blaszkowski, are highly ornamented with straight, Y-shaped, and convoluted ridges. Hence, these properties resemble those of the germination shield originally characterized by Koske and Walker (1985), but differ from those given by Morton (1995). The germination shield of S. persica spores examined by Morton (1995) was ornamented with densely distributed papillate ingrowths and outgrowths. This suggests that the properties of a germination shield are variable and, therefore, are a week criterion in delimitation of species of the genus Scutellospora.
Other species of the genus Scutellospora forming spores ornamented with warts are S. coralloidea (Trappe, Gerd. & Ho) Walker & Koske, S. gregaria (Schenck & Nicol.) Walker & Sanders, S. heterogama (Nicol. & Gerd.) Walker & Sanders, and S. verrucosa (Koske & Walker) Walker & Sanders. The shape and size of warts are the main properties separating S. persica (rounded warts; 0.3-0.5 µm wide x 0.2-0.7 µm high) from S. coralloidea (flattened warts; 2-12 µm wide x 1-2 µm high) and S. gregaria (rounded warts; 2-7 µm wide x 1-2 µm high; Morton 1995; Blaszkowski, pers. observ.). Scutellospora heterogama produces smaller spores (100-280 µm diam vs. 270-435 µm diam in S. persica) with larger warts (1-5 µm high vs. 0.5 µm high in S. persica) and with two 2-layered inner walls (vs. one 2-layered wall in S. persica; Franke and Morton 1994). Spores of S. verrucosa are lighter-colored [pale-straw to pale yellow-brown vs. pale to dark copper (Morton 1995) or sunflower yellow to apricot yellow in S. persica (Blaszkowski, pers. observ.)] and have larger warts (0.5-1 µm wide x 0.5-1 µm high vs. 0.3-0.5 µm wide x 0.2-0.7µm high in S. persica; Morton 1995; Blaszkowski, pers. observ.).
REFERENCES
Bergen M., Koske R. E. 1984. Vesicular-arbuscular mycorrhizal fungi from sand dunes of Cape Cod, Massachusetts. Trans. Br. Mycol. Soc. 83, 157-158.
Blaszkowski J., Tadych M. 1997. Scutellospora persica (Glomales, Zygomycetes), an arbuscular mycorrhizal fungus new to the mycota of Poland. Mycotaxon 65, 379-390.
Friese C. F., Koske R. E. 1991. The spatial dispersion of spores of vesicular-arbuscular mycorrhizal fungi in a sand dune: microscale patterns associated with the root architecture of American beachgrass. Mycol. Res. 95, 952-957.
Franke M., Morton J. B. 1994. Ontogenetic comparisons of arbuscular mycorrhizal fungi Scutellospora heterogama and Scutellospora pellucida: revision of taxonomic character concepts, species descriptions, and phylogenetic hypotheses. Can. J. Bot. 72, 122-134.
Gemma J. N., Koske R. E. 1989. Field inoculation of American beachgrass (Ammophila breviligulata) with V-A mycorrhizal fungi. J. Environm. Manag. 29, 173-182.
Gemma J. N., Koske R. E., Carreiro M. 1989. Seasonal dynamics of selected species of VA mycorrhizal fungi in a sand dune. Mycol. Res. 92, 317-321.
Koske R. E. 1987. Distribution of VA mycorrhizal fungi along a latitudinal temperature gradient. Mycologia 79, 55-68.
Koske R. E., Gemma J. N. 1997. Mycorrhizae and succession in plantings of beachgrass in sand dunes. Amer. J. Bot. 84, 118-130.
Koske R. E., Walker C. 1985. Species of Gigaspora (Endogonaceae) with roughened outer walls. Mycologia 77, 702-720.
Morton J. M. 1995. Taxonomic and phylogenetic divergence among five Scutellospora species based on comparative developmental sequences. Mycologia 87, 127-137.
Puppi G., Riess S. 1987. Role and ecology of VA mycorrhizae in sand dunes. Angew. Botanik 61, 115-126.
Tadych M., Blaszkowski J. 2000. Arbuscular fungi and mycorrhizae (Glomales) of the Slowinski National Park, Poland. Mycotaxon 74, 463-483.
